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.\" ========================================================================
.\"
.IX Title "BLKREPLAY 1"
.TH BLKREPLAY 1 "2015-08-16" "" ""
.\" For nroff, turn off justification.  Always turn off hyphenation; it makes
.\" way too many mistakes in technical documents.
.if n .ad l
.nh
.SH "NAME"
blkreplay \- block device testing and benchmarking tool
.SH "SYNOPSIS"
.IX Header "SYNOPSIS"
\&\fBblkreplay\fR [\fIoptions\fR] \fIdevice\fR
.SH "DESCRIPTION"
.IX Header "DESCRIPTION"
\&\fBblkreplay\fR is a utility driving the block layer of the operating
system while measuring latency and throughput of I/O operations
for later visualisation.
.PP
\&\fBblkreplay\fR can create artificial loads (random read-write sweeps,
various kinds of overload tests) or replay natural loads which
have been recorded by blktrace or a similar utility run at
production servers.
.PP
\&\fBblkreplay\fR can be used to test physical hardware, to compare
different brands of hard disks or \s-1RAID\s0 controllers, to
evaluate the effect of \s-1SSD\s0 caching, to compare different
block level transports like iSCSI vs Fibrechannel and so on.
.PP
\&\fBblkreplay\fR parses the load data from stdin. To create load data from
\&\fBblktrace\fR output, use \fBconv_blktrace_to_load.sh\fR script.
.SH "OPTIONS"
.IX Header "OPTIONS"
.IP "Influence replay duration:" 4
.IX Item "Influence replay duration:"
.RS 4
.PD 0
.IP "\fB\-\-replay\-start=\fR\fIval\fR" 4
.IX Item "--replay-start=val"
.PD
start offset (in seconds, 0=from_start)
.IP "\fB\-\-replay\-end\fR=\fIval\fR" 4
.IX Item "--replay-end=val"
end offset (in seconds, 0=unlimited)
.IP "\fB\-\-replay\-duration\fR=\fIval\fR" 4
.IX Item "--replay-duration=val"
alternatively specify the end offset as delta
.IP "\fB\-\-replay\-out\fR=\fIval\fR" 4
.IX Item "--replay-out=val"
start offset, used for output (in seconds)
.IP "\fB\-\-start\-grace\fR=\fIval\fR" 4
.IX Item "--start-grace=val"
start after grace period for filling the pipes (in seconds)
.RE
.RS 4
.RE
.IP "Handling of conflicting I/O requests:" 4
.IX Item "Handling of conflicting I/O requests:"
.RS 4
.PD 0
.IP "\fB\-\-with\-conflicts\fR" 4
.IX Item "--with-conflicts"
.PD
conflicting writes are \s-1ALLOWED \s0(damaged I/O)
.IP "\fB\-\-with\-drop\fR" 4
.IX Item "--with-drop"
conflicting writes are simply dropped
.IP "\fB\-\-with\-partial\fR" 4
.IX Item "--with-partial"
partial ordering by pushing back conflicts (default)
.IP "\fB\-\-with\-ordering\fR" 4
.IX Item "--with-ordering"
enforce total order in case of conflicts
.IP "\fB\-\-strong\fR=\fIval\fR" 4
.IX Item "--strong=val"
mode between 0 and 2, see docs (default=1)
.RE
.RS 4
.RE
.IP "Replay parameters:" 4
.IX Item "Replay parameters:"
.RS 4
.PD 0
.IP "\fB\-\-threads\fR=\fIval\fR" 4
.IX Item "--threads=val"
.PD
parallelism (default=1024)
.IP "\fB\-\-fill\-random\fR=\fIval\fR" 4
.IX Item "--fill-random=val"
fill data blocks with random bytes (%, default=0)
.RE
.RS 4
.RE
.IP "Verification modes:" 4
.IX Item "Verification modes:"
.RS 4
.PD 0
.IP "\fB\-\-no\-overhead\fR" 4
.IX Item "--no-overhead"
.PD
verify is \s-1OFF \s0(default)
.IP "\fB\-\-with\-verify\fR" 4
.IX Item "--with-verify"
verify on reads
.IP "\fB\-\-with\-final\-verify\fR" 4
.IX Item "--with-final-verify"
additional verify pass at the end
.IP "\fB\-\-with\-paranoia\fR" 4
.IX Item "--with-paranoia"
re-read after each write (destroys performance)
.RE
.RS 4
.RE
.IP "Convenience:" 4
.IX Item "Convenience:"
.RS 4
.PD 0
.IP "\fB\-\-verbose\fR=\fIval\fR" 4
.IX Item "--verbose=val"
.PD
increase verbosity, show additional \s-1INFO:\s0 output
.RE
.RS 4
.RE
.IP "Expert options (\s-1DANGEROUS\s0):" 4
.IX Item "Expert options (DANGEROUS):"
.RS 4
.PD 0
.IP "\fB\-\-o\-direct\fR" 4
.IX Item "--o-direct"
.PD
use O_DIRECT (default)
.IP "\fB\-\-no\-o\-direct\fR" 4
.IX Item "--no-o-direct"
don't use O_DIRECT, deliver \s-1FAKE\s0 results
.IP "\fB\-\-o\-sync\fR" 4
.IX Item "--o-sync"
use O_SYNC
.IP "\fB\-\-no\-o\-sync\fR" 4
.IX Item "--no-o-sync"
don't use O_SYNC (default)
.IP "\fB\-\-dry\-run\fR" 4
.IX Item "--dry-run"
don't actually do I/O, measure internal overhead
.IP "\fB\-\-fake\-io\fR" 4
.IX Item "--fake-io"
omit \fIlseek()\fR and tags, even less internal overhead
.IP "\fB\-\-simulate\-io\fR=\fIval\fR" 4
.IX Item "--simulate-io=val"
delay value for I/O simulation (timespec \fIsec.nsec\fR)
.IP "\fB\-\-ahead\-limit\fR=\fIval\fR" 4
.IX Item "--ahead-limit=val"
limit pipe fillahead (realtime \fIsec.nsec\fR)
.IP "\fB\-\-fan\-out\fR=\fIval\fR" 4
.IX Item "--fan-out=val"
only for kernel hackers (default=4)
.IP "\fB\-\-no\-dispatcher\fR" 4
.IX Item "--no-dispatcher"
only for kernel hackers
.IP "\fB\-\-bottleneck\fR=\fIval\fR" 4
.IX Item "--bottleneck=val"
max #requests on dispatch
.IP "\fB\-\-speedup\fR=\fIval\fR" 4
.IX Item "--speedup=val"
speedup / slowdown by \s-1REAL\s0 factor (default=1.0)
.IP "\fB\-\-mmap\-mode\fR" 4
.IX Item "--mmap-mode"
use \fImmap()\fR instead of \fIread()\fR / \fIwrite()\fR [\s-1NYI\s0]
.RE
.RS 4
.RE
.SH "AUTHORS"
.IX Header "AUTHORS"
\&\fBblkreplay\fR was written by Thomas Schoebel-Theuer. This manual page was created from \fBblkreplay\fR documentation by Andrew Shadura.
.SH "COPYRIGHT"
.IX Header "COPYRIGHT"
Copyright 2009\-2012 Thomas Schoebel-Theuer
.SH "SEE ALSO"
.IX Header "SEE ALSO"
\&\fIblktrace\fR\|(8)