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DRBDSETUP(8) | System Administration | DRBDSETUP(8) |
NAME¶
drbdsetup - Setup tool for DRBD .SYNOPSIS¶
drbdsetup new-resource resource
[--cpu-mask { val}]
[--on-no-data-accessible {io-error | suspend-io}]
drbdsetup new-minor resource minor
volume
drbdsetup del-resource resource
drbdsetup del-minor minor
drbdsetup attach minor lower_dev
meta_data_dev meta_data_index [--size {val}]
[--max-bio-bvecs { val}]
[--on-io-error {pass_on | call-local-io-error | detach}]
[--fencing {dont-care | resource-only | resource-and-stonith}]
[--disk-barrier] [--disk-flushes] [--disk-drain] [--md-flushes]
[--resync-rate { val}] [--resync-after {val}]
[--al-extents { val}] [--al-updates]
[--c-plan-ahead {val}] [--c-delay-target { val}]
[--c-fill-target { val}] [--c-max-rate {val}]
[--c-min-rate { val}] [--disk-timeout {val}]
[--read-balancing {prefer-local | prefer-remote | round-robin | least-pending | when-congested-remote | 32K-striping | 64K-striping | 128K-striping | 256K-striping | 512K-striping | 1M-striping}]
drbdsetup connect resource local_addr
remote_addr [--tentative] [--discard-my-data]
[--protocol {A | B | C}]
[--timeout { val}] [--max-epoch-size {val}]
[--max-buffers { val}] [--unplug-watermark {val}]
[--connect-int { val}] [--ping-int {val}]
[--sndbuf-size { val}] [--rcvbuf-size {val}]
[--ko-count { val}] [--allow-two-primaries]
[--cram-hmac-alg { val}] [--shared-secret {val}]
[--after-sb-0pri {disconnect | discard-younger-primary | discard-older-primary | discard-zero-changes | discard-least-changes | discard-local | discard-remote}]
[--after-sb-1pri {disconnect | consensus | discard-secondary | call-pri-lost-after-sb | violently-as0p}]
[--after-sb-2pri {disconnect | call-pri-lost-after-sb | violently-as0p}]
[--always-asbp]
[--rr-conflict {disconnect | call-pri-lost | violently}]
[--ping-timeout { val}]
[--data-integrity-alg {val}] [--tcp-cork]
[--on-congestion {block | pull-ahead | disconnect}]
[--congestion-fill { val}]
[--congestion-extents {val}] [--csums-alg { val}]
[--csums-after-crash-only] [--verify-alg { val}] [--use-rle]
[--socket-check-timeout { val}]
drbdsetup disk-options minor
[--on-io-error {pass_on | call-local-io-error | detach}]
[--fencing {dont-care | resource-only | resource-and-stonith}]
[--disk-barrier] [--disk-flushes] [--disk-drain] [--md-flushes]
[--resync-rate { val}] [--resync-after {val}]
[--al-extents { val}] [--al-updates]
[--c-plan-ahead {val}] [--c-delay-target { val}]
[--c-fill-target { val}] [--c-max-rate {val}]
[--c-min-rate { val}] [--disk-timeout {val}]
[--read-balancing {prefer-local | prefer-remote | round-robin | least-pending | when-congested-remote | 32K-striping | 64K-striping | 128K-striping | 256K-striping | 512K-striping | 1M-striping}]
drbdsetup net-options local_addr
remote_addr [--protocol {A | B | C}]
[--timeout { val}] [--max-epoch-size {val}]
[--max-buffers { val}] [--unplug-watermark {val}]
[--connect-int { val}] [--ping-int {val}]
[--sndbuf-size { val}] [--rcvbuf-size {val}]
[--ko-count { val}] [--allow-two-primaries]
[--cram-hmac-alg { val}] [--shared-secret {val}]
[--after-sb-0pri {disconnect | discard-younger-primary | discard-older-primary | discard-zero-changes | discard-least-changes | discard-local | discard-remote}]
[--after-sb-1pri {disconnect | consensus | discard-secondary | call-pri-lost-after-sb | violently-as0p}]
[--after-sb-2pri {disconnect | call-pri-lost-after-sb | violently-as0p}]
[--always-asbp]
[--rr-conflict {disconnect | call-pri-lost | violently}]
[--ping-timeout { val}]
[--data-integrity-alg {val}] [--tcp-cork]
[--on-congestion {block | pull-ahead | disconnect}]
[--congestion-fill { val}]
[--congestion-extents {val}] [--csums-alg { val}]
[--csums-after-crash-only] [--verify-alg { val}] [--use-rle]
[--socket-check-timeout { val}]
drbdsetup resource-options resource
[--cpu-mask { val}]
[--on-no-data-accessible {io-error | suspend-io}]
drbdsetup disconnect local_addr remote_addr
[--force]
drbdsetup detach minor [--force]
drbdsetup primary minor [--force]
drbdsetup secondary minor
drbdsetup down resource
drbdsetup verify minor
[--start {val}] [--stop { val}]
drbdsetup invalidate minor
drbdsetup invalidate-remote minor
drbdsetup wait-connect minor
[--wfc-timeout { val}] [--degr-wfc-timeout {val}]
[--outdated-wfc-timeout { val}]
[--wait-after-sb {val}]
drbdsetup wait-sync minor
[--wfc-timeout {val}] [--degr-wfc-timeout {val}]
[--outdated-wfc-timeout { val}]
[--wait-after-sb {val}]
drbdsetup role minor
drbdsetup cstate minor
drbdsetup dstate minor
drbdsetup resize minor
[--size {val}] [--assume-peer-has-space] [--assume-clean]
[--al-stripes { val}]
[--al-stripe-size-kB {val}]
drbdsetup check-resize minor
drbdsetup pause-sync minor
drbdsetup resume-sync minor
drbdsetup outdate minor
drbdsetup show-gi minor
drbdsetup get-gi minor
drbdsetup show {resource | minor |
all}
drbdsetup suspend-io minor
drbdsetup resume-io minor
drbdsetup events {resource | minor |
all}
drbdsetup new-current-uuid minor
[--clear-bitmap]
DESCRIPTION¶
drbdsetup is used to associate DRBD devices with their backing block devices, to set up DRBD device pairs to mirror their backing block devices, and to inspect the configuration of running DRBD devices.NOTE¶
drbdsetup is a low level tool of the DRBD program suite. It is used by the data disk and drbd scripts to communicate with the device driver.COMMANDS¶
Each drbdsetup sub-command might require arguments and bring its own set of options. All values have default units which might be overruled by K, M or G. These units are defined in the usual way (e.g. K = 2^10 = 1024).Common options¶
All drbdsetup sub-commands accept these two options --create-deviceIn case the specified DRBD device (minor number) does not
exist yet, create it implicitly.
new-resource¶
Resources are the primary objects of any DRBD configuration. A resource must be created with the new-resource command before any volumes or minor devices can be created. Connections are referenced by name.new-minor¶
A minor is used as a synonym for replicated block device. It is represented in the /dev/ directory by a block device. It is the application's interface to the DRBD-replicated block devices. These block devices get addressed by their minor numbers on the drbdsetup commandline. A pair of replicated block devices may have different minor numbers on the two machines. They are associated by a common volume-number. Volume numbers are local to each connection. Minor numbers are global on one node.del-resource¶
Destroys a resource object. This is only possible if the resource has no volumes.del-minor¶
Minors can only be destroyed if its disk is detached.attach, disk-options¶
Attach associates device with lower_device to store its data blocks on. The -d (or --disk-size) should only be used if you wish not to use as much as possible from the backing block devices. If you do not use -d, the device is only ready for use as soon as it was connected to its peer once. (See the net command.) With the disk-options command it is possible to change the options of a minor while it is attached. --disk-size sizeYou can override DRBD's size determination method with
this option. If you need to use the device before it was ever connected to its
peer, use this option to pass the size of the DRBD device to the
driver. Default unit is sectors (1s = 512 bytes).
If you use the size parameter in drbd.conf, we strongly recommend to add
an explicit unit postfix. drbdadm and drbdsetup used to have mismatching
default units.
--on-io-error err_handler
If the driver of the lower_device reports an error
to DRBD, DRBD will mark the disk as inconsistent, call a helper program, or
detach the device from its backing storage and perform all further IO by
requesting it from the peer. The valid err_handlers are:
pass_on, call-local-io-error and detach.
--fencing fencing_policy
Under fencing we understand preventive measures to
avoid situations where both nodes are primary and disconnected (AKA split
brain).
Valid fencing policies are:
dont-care
--disk-barrier,
This is the default policy. No fencing actions are
done.
resource-only
If a node becomes a disconnected primary, it tries to
outdate the peer's disk. This is done by calling the fence-peer handler. The
handler is supposed to reach the other node over alternative communication
paths and call 'drbdadm outdate res' there.
resource-and-stonith
If a node becomes a disconnected primary, it freezes all
its IO operations and calls its fence-peer handler. The fence-peer handler is
supposed to reach the peer over alternative communication paths and call
'drbdadm outdate res' there. In case it cannot reach the peer, it should
stonith the peer. IO is resumed as soon as the situation is resolved. In case
your handler fails, you can resume IO with the resume-io command.
DRBD has four implementations to express
write-after-write dependencies to its backing storage device. DRBD will use
the first method that is supported by the backing storage device and that is
not disabled. By default the flush method is used.
Since drbd-8.4.2 disk-barrier is disabled by default because since
linux-2.6.36 (or 2.6.32 RHEL6) there is no reliable way to determine if
queuing of IO-barriers works. Dangerous only enable if you are told so
by one that knows for sure.
When selecting the method you should not only base your decision on the
measurable performance. In case your backing storage device has a volatile
write cache (plain disks, RAID of plain disks) you should use one of the first
two. In case your backing storage device has battery-backed write cache you
may go with option 3. Option 4 (disable everything, use "none")
is dangerous on most IO stacks, may result in write-reordering, and if
so, can theoretically be the reason for data corruption, or disturb the DRBD
protocol, causing spurious disconnect/reconnect cycles. Do not
useno-disk-drain.
Unfortunately device mapper (LVM) might not support barriers.
The letter after "wo:" in /proc/drbd indicates with method is
currently in use for a device: b, f, d, n. The implementations:
barrier
--md-flushes
The first requires that the driver of the backing storage
device support barriers (called 'tagged command queuing' in SCSI and 'native
command queuing' in SATA speak). The use of this method can be enabled by
setting the disk-barrier options to yes.
flush
The second requires that the backing device support disk
flushes (called 'force unit access' in the drive vendors speak). The use of
this method can be disabled setting disk-flushes to no.
drain
The third method is simply to let write requests drain
before write requests of a new reordering domain are issued. That was the only
implementation before 8.0.9.
none
The fourth method is to not express write-after-write
dependencies to the backing store at all, by also specifying
--no-disk-drain. This is dangerous on most IO stacks, may result
in write-reordering, and if so, can theoretically be the reason for data
corruption, or disturb the DRBD protocol, causing spurious
disconnect/reconnect cycles. Do not use--no-disk-drain.
Disables the use of disk flushes and barrier BIOs when
accessing the meta data device. See the notes on --disk-flushes.
--max-bio-bvecs
In some special circumstances the device mapper stack
manages to pass BIOs to DRBD that violate the constraints that are set forth
by DRBD's merge_bvec() function and which have more than one bvec. A known
example is: phys-disk -> DRBD -> LVM -> Xen -> missaligned
partition (63) -> DomU FS. Then you might see "bio would need to, but
cannot, be split:" in the Dom0's kernel log.
The best workaround is to proper align the partition within the VM (E.g. start
it at sector 1024). That costs 480 KiB of storage. Unfortunately the default
of most Linux partitioning tools is to start the first partition at an odd
number (63). Therefore most distributions install helpers for virtual linux
machines will end up with missaligned partitions. The second best workaround
is to limit DRBD's max bvecs per BIO (i.e., the max-bio-bvecs option)
to 1, but that might cost performance.
The default value of max-bio-bvecs is 0, which means that there is no
user imposed limitation.
--resync-rate rate
To ensure smooth operation of the application on top of
DRBD, it is possible to limit the bandwidth that may be used by background
synchronization. The default is 250 KiB/sec, the default unit is
KiB/sec.
--resync-after minor
Start resync on this device only if the device with
minor is already in connected state. Otherwise this device waits in
SyncPause state.
--al-extents extents
DRBD automatically performs hot area detection. With this
parameter you control how big the hot area (=active set) can get. Each extent
marks 4M of the backing storage. In case a primary node leaves the cluster
unexpectedly, the areas covered by the active set must be resynced upon
rejoining of the failed node. The data structure is stored in the meta-data
area, therefore each change of the active set is a write operation to the
meta-data device. A higher number of extents gives longer resync times but
less updates to the meta-data. The default number of extents is 1237.
(Minimum: 7, Maximum: 65534)
See also drbd.conf(5) and drbdmeta(8) for additional limitations
and necessary preparation.
--al-updates {yes | no}
DRBD's activity log transaction writing makes it
possible, that after the crash of a primary node a partial (bit-map based)
resync is sufficient to bring the node back to up-to-date. Setting
al-updates to no might increase normal operation performance but
causes DRBD to do a full resync when a crashed primary gets reconnected. The
default value is yes.
--c-plan-ahead plan_time,
The dynamic resync speed controller gets enabled with
setting plan_time to a positive value. It aims to fill the buffers
along the data path with either a constant amount of data fill_target,
or aims to have a constant delay time of delay_target along the path.
The controller has an upper bound of max_rate.
By plan_time the agility of the controller is configured. Higher values
yield for slower/lower responses of the controller to deviation from the
target value. It should be at least 5 times RTT. For regular data paths a
fill_target in the area of 4k to 100k is appropriate. For a setup that
contains drbd-proxy it is advisable to use delay_target instead. Only
when fill_target is set to 0 the controller will use
delay_target. 5 times RTT is a reasonable starting value.
Max_rate should be set to the bandwidth available between the
DRBD-hosts and the machines hosting DRBD-proxy, or to the available
disk-bandwidth.
The default value of plan_time is 0, the default unit is 0.1 seconds.
Fill_target has 0 and sectors as default unit. Delay_target has
1 (100ms) and 0.1 as default unit. Max_rate has 10240 (100MiB/s) and
KiB/s as default unit.
--c-min-rate min_rate
We track the disk IO rate caused by the resync, so we can
detect non-resync IO on the lower level device. If the lower level device
seems to be busy, and the current resync rate is above min_rate, we
throttle the resync.
The default value of min_rate is 4M, the default unit is k. If you want
to not throttle at all, set it to zero, if you want to throttle always, set it
to one.
-t, --disk-timeout disk_timeout
If the lower-level device on which a DRBD device stores
its data does not finish an I/O request within the defined
disk-timeout, DRBD treats this as a failure. The lower-level device is
detached, and the device's disk state advances to Diskless. If DRBD is
connected to one or more peers, the failed request is passed on to one of
them.
This option is dangerous and may lead to kernel panic!
"Aborting" requests, or force-detaching the disk, is intended for
completely blocked/hung local backing devices which do no longer complete
requests at all, not even do error completions. In this situation, usually a
hard-reset and failover is the only way out.
By "aborting", basically faking a local error-completion, we allow for
a more graceful swichover by cleanly migrating services. Still the affected
node has to be rebooted "soon".
By completing these requests, we allow the upper layers to re-use the associated
data pages.
If later the local backing device "recovers", and now DMAs some data
from disk into the original request pages, in the best case it will just put
random data into unused pages; but typically it will corrupt meanwhile
completely unrelated data, causing all sorts of damage.
Which means delayed successful completion, especially for READ requests, is a
reason to panic(). We assume that a delayed *error* completion is OK, though
we still will complain noisily about it.
The default value of disk-timeout is 0, which stands for an infinite
timeout. Timeouts are specified in units of 0.1 seconds. This option is
available since DRBD 8.3.12.
--read-balancing method
The supported methods for load balancing of read
requests are prefer-local, prefer-remote, round-robin,
least-pending and when-congested-remote, 32K-striping,
64K-striping, 128K-striping, 256K-striping,
512K-striping and 1M-striping.
The default value of is prefer-local. This option is available since
8.4.1.
connect, net-options¶
Connect sets up the device to listen on af:local_addr:port for incoming connections and to try to connect to af:remote_addr:port. If port is omitted, 7788 is used as default. If af is omitted ipv4 gets used. Other supported address families are ipv6, ssocks for Dolphin Interconnect Solutions' "super sockets" and sdp for Sockets Direct Protocol (Infiniband). The net-options command allows you to change options while the connection is established. --protocol protocolOn the TCP/IP link the specified protocol is used.
Valid protocol specifiers are A, B, and C.
Protocol A: write IO is reported as completed, if it has reached local disk and
local TCP send buffer.
Protocol B: write IO is reported as completed, if it has reached local disk and
remote buffer cache.
Protocol C: write IO is reported as completed, if it has reached both local and
remote disk.
--connect-int time
In case it is not possible to connect to the remote DRBD
device immediately, DRBD keeps on trying to connect. With this option you can
set the time between two retries. The default value is 10. The unit is
seconds.
--ping-int time
If the TCP/IP connection linking a DRBD device pair is
idle for more than time seconds, DRBD will generate a keep-alive packet
to check if its partner is still alive. The default value is 10. The unit is
seconds.
--timeout val
If the partner node fails to send an expected response
packet within val tenths of a second, the partner node is considered
dead and therefore the TCP/IP connection is abandoned. The default value is 60
(= 6 seconds).
--sndbuf-size size
The socket send buffer is used to store packets sent to
the secondary node, which are not yet acknowledged (from a network point of
view) by the secondary node. When using protocol A, it might be necessary to
increase the size of this data structure in order to increase asynchronicity
between primary and secondary nodes. But keep in mind that more asynchronicity
is synonymous with more data loss in the case of a primary node failure. Since
8.0.13 resp. 8.2.7 setting the size value to 0 means that the kernel
should autotune this. The default size is 0, i.e. autotune.
--rcvbuf-size size
Packets received from the network are stored in the
socket receive buffer first. From there they are consumed by DRBD. Before
8.3.2 the receive buffer's size was always set to the size of the socket send
buffer. Since 8.3.2 they can be tuned independently. A value of 0 means that
the kernel should autotune this. The default size is 0, i.e.
autotune.
--ko-count count
In case the secondary node fails to complete a single
write request for count times the timeout, it is expelled from
the cluster, i.e. the primary node goes into StandAlone mode. The default is
0, which disables this feature.
--max-epoch-size val
With this option the maximal number of write requests
between two barriers is limited. Typically set to the same as
--max-buffers, or the allowed maximum. Values smaller than 10 can lead
to degraded performance. The default value is 2048.
--max-buffers val
With this option the maximal number of buffer pages
allocated by DRBD's receiver thread is limited. Typically set to the same as
--max-epoch-size. Small values could lead to degraded performance. The
default value is 2048, the minimum 32. Increase this if you cannot saturate
the IO backend of the receiving side during linear write or during resync
while otherwise idle.
See also drbd.conf(5)
--unplug-watermark val
This setting has no effect with recent kernels that use
explicit on-stack plugging (upstream Linux kernel 2.6.39, distributions may
have backported).
When the number of pending write requests on the standby (secondary) node
exceeds the unplug-watermark, we trigger the request processing of our backing
storage device. Some storage controllers deliver better performance with small
values, others deliver best performance when the value is set to the same
value as max-buffers, yet others don't feel much effect at all. Minimum 16,
default 128, maximum 131072.
--allow-two-primaries
With this option set you may assign primary role to both
nodes. You only should use this option if you use a shared storage file system
on top of DRBD. At the time of writing the only ones are: OCFS2 and GFS. If
you use this option with any other file system, you are going to crash your
nodes and to corrupt your data!
--cram-hmac-alg alg
You need to specify the HMAC algorithm to enable peer
authentication at all. You are strongly encouraged to use peer authentication.
The HMAC algorithm will be used for the challenge response authentication of
the peer. You may specify any digest algorithm that is named in
/proc/crypto.
--shared-secret secret
The shared secret used in peer authentication. May be up
to 64 characters.
--after-sb-0pri asb-0p-policy
possible policies are:
disconnect
--after-sb-1pri asb-1p-policy
No automatic resynchronization, simply disconnect.
discard-younger-primary
Auto sync from the node that was primary before the
split-brain situation occurred.
discard-older-primary
Auto sync from the node that became primary as second
during the split-brain situation.
discard-zero-changes
In case one node did not write anything since the split
brain became evident, sync from the node that wrote something to the node that
did not write anything. In case none wrote anything this policy uses a random
decision to perform a "resync" of 0 blocks. In case both have
written something this policy disconnects the nodes.
discard-least-changes
Auto sync from the node that touched more blocks during
the split brain situation.
discard-node-NODENAME
Auto sync to the named node.
possible policies are:
disconnect
--after-sb-2pri asb-2p-policy
No automatic resynchronization, simply disconnect.
consensus
Discard the version of the secondary if the outcome of
the after-sb-0pri algorithm would also destroy the current secondary's
data. Otherwise disconnect.
discard-secondary
Discard the secondary's version.
call-pri-lost-after-sb
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current secondary has the correct data, call
the pri-lost-after-sb on the current primary.
violently-as0p
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current secondary has the correct data,
accept a possible instantaneous change of the primary's data.
possible policies are:
disconnect
--always-asbp
No automatic resynchronization, simply disconnect.
call-pri-lost-after-sb
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current secondary has the right data, call
the pri-lost-after-sb on the current primary.
violently-as0p
Always honor the outcome of the after-sb-0pri
algorithm. In case it decides the current secondary has the right data, accept
a possible instantaneous change of the primary's data.
Normally the automatic after-split-brain policies are
only used if current states of the UUIDs do not indicate the presence of a
third node.
With this option you request that the automatic after-split-brain policies are
used as long as the data sets of the nodes are somehow related. This might
cause a full sync, if the UUIDs indicate the presence of a third node. (Or
double faults have led to strange UUID sets.)
--rr-conflict role-resync-conflict-policy
This option sets DRBD's behavior when DRBD deduces from
its meta data that a resynchronization is needed, and the SyncTarget node is
already primary. The possible settings are: disconnect,
call-pri-lost and violently. While disconnect speaks for
itself, with the call-pri-lost setting the pri-lost handler is
called which is expected to either change the role of the node to secondary,
or remove the node from the cluster. The default is disconnect.
With the violently setting you allow DRBD to force a primary node into
SyncTarget state. This means that the data exposed by DRBD changes to the
SyncSource's version of the data instantaneously. USE THIS OPTION ONLY IF YOU
KNOW WHAT YOU ARE DOING.
--data-integrity-alg hash_alg
DRBD can ensure the data integrity of the user's data on
the network by comparing hash values. Normally this is ensured by the 16 bit
checksums in the headers of TCP/IP packets. This option can be set to any of
the kernel's data digest algorithms. In a typical kernel configuration you
should have at least one of md5, sha1, and crc32c
available. By default this is not enabled.
See also the notes on data integrity on the drbd.conf manpage.
--no-tcp-cork
DRBD usually uses the TCP socket option TCP_CORK to hint
to the network stack when it can expect more data, and when it should flush
out what it has in its send queue. There is at least one network stack that
performs worse when one uses this hinting method. Therefore we introduced this
option, which disable the setting and clearing of the TCP_CORK socket option
by DRBD.
--ping-timeout ping_timeout
The time the peer has to answer to a keep-alive packet.
In case the peer's reply is not received within this time period, it is
considered dead. The default unit is tenths of a second, the default value is
5 (for half a second).
--discard-my-data
Use this option to manually recover from a split-brain
situation. In case you do not have any automatic after-split-brain policies
selected, the nodes refuse to connect. By passing this option you make this
node a sync target immediately after successful connect.
--tentative
Causes DRBD to abort the connection process after the
resync handshake, i.e. no resync gets performed. You can find out which resync
DRBD would perform by looking at the kernel's log file.
--on-congestion congestion_policy,
By default DRBD blocks when the available TCP send queue
becomes full. That means it will slow down the application that generates the
write requests that cause DRBD to send more data down that TCP connection.
When DRBD is deployed with DRBD-proxy it might be more desirable that DRBD goes
into AHEAD/BEHIND mode shortly before the send queue becomes full. In
AHEAD/BEHIND mode DRBD does no longer replicate data, but still keeps the
connection open.
The advantage of the AHEAD/BEHIND mode is that the application is not slowed
down, even if DRBD-proxy's buffer is not sufficient to buffer all write
requests. The downside is that the peer node falls behind, and that a resync
will be necessary to bring it back into sync. During that resync the peer node
will have an inconsistent disk.
Available congestion_policys are block and pull-ahead. The
default is block. Fill_threshold might be in the range of 0 to
10GiBytes. The default is 0 which disables the check.
Active_extents_threshold has the same limits as al-extents.
The AHEAD/BEHIND mode and its settings are available since DRBD 8.3.10.
--verify-alg hash-alg
During online verification (as initiated by the
verify sub-command), rather than doing a bit-wise comparison, DRBD
applies a hash function to the contents of every block being verified, and
compares that hash with the peer. This option defines the hash algorithm being
used for that purpose. It can be set to any of the kernel's data digest
algorithms. In a typical kernel configuration you should have at least one of
md5, sha1, and crc32c available. By default this is not
enabled; you must set this option explicitly in order to be able to use
on-line device verification.
See also the notes on data integrity on the drbd.conf manpage.
--csums-alg hash-alg
A resync process sends all marked data blocks form the
source to the destination node, as long as no csums-alg is given. When
one is specified the resync process exchanges hash values of all marked blocks
first, and sends only those data blocks over, that have different hash values.
This setting is useful for DRBD setups with low bandwidth links. During the
restart of a crashed primary node, all blocks covered by the activity log are
marked for resync. But a large part of those will actually be still in sync,
therefore using csums-alg will lower the required bandwidth in exchange
for CPU cycles.
--use-rle
During resync-handshake, the dirty-bitmaps of the nodes
are exchanged and merged (using bit-or), so the nodes will have the same
understanding of which blocks are dirty. On large devices, the fine grained
dirty-bitmap can become large as well, and the bitmap exchange can take quite
some time on low-bandwidth links.
Because the bitmap typically contains compact areas where all bits are unset
(clean) or set (dirty), a simple run-length encoding scheme can considerably
reduce the network traffic necessary for the bitmap exchange.
For backward compatibility reasons, and because on fast links this possibly does
not improve transfer time but consumes cpu cycles, this defaults to off.
Introduced in 8.3.2.
resource-options¶
Changes the options of the resource at runtime. --cpu-mask cpu-maskSets the cpu-affinity-mask for DRBD's kernel threads of
this device. The default value of cpu-mask is 0, which means that
DRBD's kernel threads should be spread over all CPUs of the machine. This
value must be given in hexadecimal notation. If it is too big it will be
truncated.
--on-no-data-accessible ond-policy
This setting controls what happens to IO requests on a
degraded, disk less node (I.e. no data store is reachable). The available
policies are io-error and suspend-io.
If ond-policy is set to suspend-io you can either resume IO by
attaching/connecting the last lost data storage, or by the drbdadm
resume-io res command. The latter will result in IO errors
of course.
The default is io-error. This setting is available since DRBD
8.3.9.
primary¶
Sets the device into primary role. This means that applications (e.g. a file system) may open the device for read and write access. Data written to the device in primary role are mirrored to the device in secondary role. Normally it is not possible to set both devices of a connected DRBD device pair to primary role. By using the --allow-two-primaries option, you override this behavior and instruct DRBD to allow two primaries. --overwrite-data-of-peerAlias for --force.
--force
Becoming primary fails if the local replica is not
up-to-date. I.e. when it is inconsistent, outdated of consistent. By using
this option you can force it into primary role anyway. USE THIS OPTION ONLY IF
YOU KNOW WHAT YOU ARE DOING.
secondary¶
Brings the device into secondary role. This operation fails as long as at least one application (or file system) has opened the device. It is possible that both devices of a connected DRBD device pair are secondary.verify¶
This initiates on-line device verification. During on-line verification, the contents of every block on the local node are compared to those on the peer node. Device verification progress can be monitored via /proc/drbd. Any blocks whose content differs from that of the corresponding block on the peer node will be marked out-of-sync in DRBD's on-disk bitmap; they are not brought back in sync automatically. To do that, simply disconnect and reconnect the resource. If on-line verification is already in progress (and this node is "VerifyS"), this command silently "succeeds". In this case, any start-sector (see below) will be ignored, and any stop-sector (see below) will be honored. This can be used to stop a running verify, or to update/shorten/extend the coverage of the currently running verify. This command will fail if the device is not part of a connected device pair. See also the notes on data integrity on the drbd.conf manpage. --start start-sectorSince version 8.3.2, on-line verification should resume
from the last position after connection loss. It may also be started from an
arbitrary position by setting this option. If you had reached some stop-sector
before, and you do not specify an explicit start-sector, verify should resume
from the previous stop-sector.
Default unit is sectors. You may also specify a unit explicitly. The
start-sector will be rounded down to a multiple of 8 sectors
(4kB).
-S, --stop stop-sector
Since version 8.3.14, on-line verification can be stopped
before it reaches end-of-device.
Default unit is sectors. You may also specify a unit explicitly. The
stop-sector may be updated by issuing an additional drbdsetup verify
command on the same node while the verify is running. This can be used to stop
a running verify, or to update/shorten/extend the coverage of the currently
running verify.
invalidate¶
This forces the local device of a pair of connected DRBD devices into SyncTarget state, which means that all data blocks of the device are copied over from the peer. This command will fail if the device is not either part of a connected device pair, or disconnected Secondary.invalidate-remote¶
This forces the local device of a pair of connected DRBD devices into SyncSource state, which means that all data blocks of the device are copied to the peer. On a disconnected Primary device, this will set all bits in the out of sync bitmap. As a side affect this suspends updates to the on disk activity log. Updates to the on disk activity log resume automatically when necessary.wait-connect¶
Returns as soon as the device can communicate with its partner device. --wfc-timeout wfc_timeout,This command will fail if the device cannot
communicate with its partner for timeout seconds. If the peer was
working before this node was rebooted, the wfc_timeout is used. If the
peer was already down before this node was rebooted, the
degr_wfc_timeout is used. If the peer was successfully outdated before
this node was rebooted the outdated_wfc_timeout is used. The default
value for all those timeout values is 0 which means to wait forever. The unit
is seconds. In case the connection status goes down to StandAlone because the
peer appeared but the devices had a split brain situation, the default for the
command is to terminate. You can change this behavior with the
--wait-after-sb option.
wait-sync¶
Returns as soon as the device leaves any synchronization into connected state. The options are the same as with the wait-connect command.disconnect¶
Removes the information set by the net command from the device. This means that the device goes into unconnected state and will no longer listen for incoming connections.detach¶
Removes the information set by the disk command from the device. This means that the device is detached from its backing storage device. -f, --forceA regular detach returns after the disk state finally
reached diskless. As a consequence detaching from a frozen backing block
device never terminates.
On the other hand A forced detach returns immediately. It allows you to detach
DRBD from a frozen backing block device. Please note that the disk will be
marked as failed until all pending IO requests where finished by the backing
block device.
down¶
Removes all configuration information from the device and forces it back to unconfigured state.role¶
Shows the current roles of the device and its peer, as local/peer.state¶
Deprecated alias for "role"cstate¶
Shows the current connection state of the device.dstate¶
Shows the current states of the backing storage devices, as local/peer.resize¶
This causes DRBD to reexamine the size of the device's backing storage device. To actually do online growing you need to extend the backing storages on both devices and call the resize command on one of your nodes. The --size option can be used to online shrink the usable size of a drbd device. It's the users responsibility to make sure that a file system on the device is not truncated by that operation. The --assume-peer-has-space allows you to resize a device which is currently not connected to the peer. Use with care, since if you do not resize the peer's disk as well, further connect attempts of the two will fail. When the --assume-clean option is given DRBD will skip the resync of the new storage. Only do this if you know that the new storage was initialized to the same content by other means. The options --al-stripes and --al-stripe-size-kB may be used to change the layout of the activity log online. In case of internal meta data this may invovle shrinking the user visible size at the same time (unsing the --size) or increasing the avalable space on the backing devices.check-resize¶
To enable DRBD to detect offline resizing of backing devices this command may be used to record the current size of backing devices. The size is stored in files in /var/lib/drbd/ named drbd-minor-??.lkbd This command is called by drbdadm resize res after drbdsetup device resize returned.pause-sync¶
Temporarily suspend an ongoing resynchronization by setting the local pause flag. Resync only progresses if neither the local nor the remote pause flag is set. It might be desirable to postpone DRBD's resynchronization after eventual resynchronization of the backing storage's RAID setup.resume-sync¶
Unset the local sync pause flag.outdate¶
Mark the data on the local backing storage as outdated. An outdated device refuses to become primary. This is used in conjunction with fencing and by the peer's fence-peer handler.show-gi¶
Displays the device's data generation identifiers verbosely.get-gi¶
Displays the device's data generation identifiers.show¶
Shows all available configuration information of the device.suspend-io¶
This command is of no apparent use and just provided for the sake of completeness.resume-io¶
If the fence-peer handler fails to stonith the peer node, and your fencing policy is set to resource-and-stonith, you can unfreeze IO operations with this command.events¶
Displays every state change of DRBD and all calls to helper programs. This might be used to get notified of DRBD's state changes by piping the output to another program. --all-devicesDisplay the events of all DRBD minors.
--unfiltered
This is a debugging aid that displays the content of all
received netlink messages.
new-current-uuid¶
Generates a new current UUID and rotates all other UUID values. This has at least two use cases, namely to skip the initial sync, and to reduce network bandwidth when starting in a single node configuration and then later (re-)integrating a remote site. Available option: --clear-bitmapClears the sync bitmap in addition to generating a new
current UUID.
This can be used to skip the initial sync, if you want to start from scratch.
This use-case does only work on "Just Created" meta data. Necessary
steps:
1.On both nodes, initialize meta data and
configure the device.
drbdadm create-md --force res
2.They need to do the initial handshake, so they know
their sizes.
drbdadm up res
3.They are now Connected Secondary/Secondary
Inconsistent/Inconsistent. Generate a new current-uuid and clear the dirty
bitmap.
drbdadm new-current-uuid --clear-bitmap res
4.They are now Connected Secondary/Secondary
UpToDate/UpToDate. Make one side primary and create a file system.
drbdadm primary res
mkfs -t fs-type $(drbdadm sh-dev
res)
One obvious side-effect is that the replica is full of old garbage (unless you
made them identical using other means), so any online-verify is expected to
find any number of out-of-sync blocks.
You must not use this on pre-existing data! Even though it may appear to
work at first glance, once you switch to the other node, your data is toast,
as it never got replicated. So do not leave out the mkfs (or
equivalent).
This can also be used to shorten the initial resync of a cluster where the
second node is added after the first node is gone into production, by means of
disk shipping. This use-case works on disconnected devices only, the device
may be in primary or secondary role.
The necessary steps on the current active server are:
1.drbdsetup new-current-uuid --clear-bitmap
minor
2.Take the copy of the current active server. E.g. by
pulling a disk out of the RAID1 controller, or by copying with dd. You need to
copy the actual data, and the meta data.
3.drbdsetup new-current-uuid
minor
Now add the disk to the new secondary node, and join it to the cluster. You will
get a resync of that parts that were changed since the first call to
drbdsetup in step 1.
EXAMPLES¶
For examples, please have a look at the DRBD User's Guide[1].VERSION¶
This document was revised for version 8.3.2 of the DRBD distribution.AUTHOR¶
Written by Philipp Reisner <philipp.reisner@linbit.com> and Lars Ellenberg <lars.ellenberg@linbit.com>REPORTING BUGS¶
Report bugs to <drbd-user@lists.linbit.com>.COPYRIGHT¶
Copyright 2001-2008 LINBIT Information Technologies, Philipp Reisner, Lars Ellenberg. This is free software; see the source for copying conditions. There is NO warranty; not even for MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.SEE ALSO¶
drbd.conf(5), drbd(8), drbddisk(8), drbdadm(8), DRBD User's Guide[1], DRBD web site[2]NOTES¶
- 1.
- DRBD User's Guide
- 2.
- DRBD web site
6 May 2011 | DRBD 8.4.0 |