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.TH SNSEQ 8 "November 2022" "Xsan File System"
.SH NAME
snseq \- Xsan cvdb "perf" trace analyzer
.SH SYNOPSIS
.na
.nh
.B snseq
.RI {read,write,rdwr}
.RI {--persec,--details,--csv}
.RI [filer_options]
.I files(s)
.PP
.B snseq
.RI devread
.I file(s)
.PP
.B snseq
.RI devwrite
.I file(s)
.PP
.B snseq
.RI -h,\ --help
.PP
.ad
.hy
.SH DESCRIPTION
\fBsnseq\fR is a tool for analyzing cvdb "perf" traces. It is useful for
determining file access patterns of applications as well as measuring
I/O latency and performance at both VFS and device levels.

Running \fBsnseq\fR first requires capturing client traces using the
\fBcvdb\fR command.  \fBsnseq\fR emits to "stdout" so capturing output
to a file requires shell redirection.

By default, \fBsnseq\fR displays a human-readable ASCII format. However,
some \fBsnseq\fR command lines allow the specification of \fI--csv\fR that
will cause it to emit CSV format that can be used with spreadsheet applications.
This is especially useful for producing graphs. Visualizing data in this
manner can provide insight into how an application is performing I/O.

.SH OPTIONS
.PP
Analysis mode:
.IP \fBread\fR
Process VFS reads.
.IP \fBwrite\fR
Process VFS writes.
.IP \fBrdwr\fR
Process VFS reads and writes.
.IP \fBdevread\fR
Process device reads.
.IP \fBdevwrite\fR
Process device writes.
.PP
filter_options:
.IP \fB--seq\fR
track largest sequential I/O stream
.IP \fB--start\fR
start time offset
.IP \fB--end\fR
end time offset
.IP \fB--proc\fR
filter by process name
.IP \fB--minsize\fR
filter out files smaller than byte_count
.PP
help:
.IP \fB-h,\ --help\fR
Just display help and exit

.SH EXAMPLE
.Cs
    # mkdir /tmp/cvdb
    # cd /tmp/cvdb
    # cvdbset perf
    # cvdb -g -C -F &
    \fItest is run here\fR
    # killall cvdb
    # snseq read --details cvdbout* > seq.out
.Ce
.SH NOTES
\fBsnseq\fR uses python. If for some reason the Python package available
on the system is incompatible with \fBsnseq\fR, installing an additional Python
package may be required to run \fBsnseq\fR. Alternatively,
cvdb "perf" traces captured on one system can often be processed on another system.  It is often possible to capture cvdb perf traces on a client and
then copy them over to the MDC and run \fBsnseq\fR there. This technique
can also be used to process perf traces taken from a backrev client, subject
to certain limitations. For example, older cvdb perf traces do not contain
enough information to display file names.
.Ce
.PP
.SH "SEE ALSO"
.BR cvdbset (8),
.BR cvdb (8)