[zfs-discuss] iostat and monitoring
Hi gurus, I like zpool iostat and I like system monitoring, so I setup a script within sma to let me get the zpool iostat figures through snmp. The problem is that as zpool iostat is only run once for each snmp query, it always reports a static set of figures, like so: [EMAIL PROTECTED]:snmp # zpool iostat -v capacity operationsbandwidth pool used avail read write read write -- - - - - - - tank 443G 1.60T 4 4 461K 467K raidz1 443G 1.60T 4 4 461K 467K c1t0d0 - - 1 2 227K 234K c1t1d0 - - 1 2 228K 234K c2t0d0 - - 1 2 227K 234K -- - - - - - - Whereas if I run it an interval, the figures even out after a few seconds. What I'm wondering is: Is there any way to get iostat to report accurate figures from a one time invocation? Alternatively is there a better way to get read/write ops etc from my pool for monitoring applications? I would really love if monitoring zfs pools from snmp was better all round, but I'm not going to reel off my wish list here at this point ;) Thanks Matt ___ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
Re: [zfs-discuss] iostat and monitoring
On Sat, Jul 5, 2008 at 2:33 PM, Matt Harrison
[EMAIL PROTECTED] wrote:
Alternatively is there a better way to get read/write ops etc from my
pool for monitoring applications?
I would really love if monitoring zfs pools from snmp was better all
round, but I'm not going to reel off my wish list here at this point ;)
You can access the kstats directly to get the counter values.
$ kstat -p ::vopstats_zfs:{nread,read_bytes,nwrite,write_bytes}
unix:0:vopstats_zfs:nread 418787
unix:0:vopstats_zfs:read_bytes 612076305
unix:0:vopstats_zfs:nwrite 163544
unix:0:vopstats_zfs:write_bytes 255725992
These are the counters used by fsstat. In the case of a single pool,
I would expect (perhaps naively) to match up with zpool iostat
numbers.
On my list of things to do when I get around to it is to enable
parseable output in fsstat(1M). See
http://mail.opensolaris.org/pipermail/on-discuss/2008-June/000127.html
for details. Parseable is currently disabled for reasons that are
discussed in the mail folder, linked at
http://opensolaris.org/os/community/arc/caselog/2006/180/.
It is interesting to look at the numbers at this level compared to
iostat. While iostat shows physical reads and writes only zpool
iostat and fsstat show reads that are satisfied by a cache and never
result in physical I/O activity. As such, a workload that looks
write-intensive on UFS monitored via iostat may seem to have shifted
to being very read intensive.
--
Mike Gerdts
http://mgerdts.blogspot.com/
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Re: [zfs-discuss] iostat and monitoring
Mike Gerdts wrote:
$ kstat -p ::vopstats_zfs:{nread,read_bytes,nwrite,write_bytes}
unix:0:vopstats_zfs:nread 418787
unix:0:vopstats_zfs:read_bytes612076305
unix:0:vopstats_zfs:nwrite163544
unix:0:vopstats_zfs:write_bytes 255725992
Thanks Mike, thats exactly what I was looking for. I can work my way
around the other snmp problems, like not reporting total space on a zfs :)
Thanks
Matt
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Re: [zfs-discuss] iostat and monitoring
On Sat, Jul 05, 2008 at 03:03:34PM -0500, Mike Gerdts wrote:
You can access the kstats directly to get the counter values.
First off, let me say that: kstat++
That's too cool.
$ kstat -p ::vopstats_zfs:{nread,read_bytes,nwrite,write_bytes}
unix:0:vopstats_zfs:nread 418787
unix:0:vopstats_zfs:read_bytes612076305
unix:0:vopstats_zfs:nwrite163544
unix:0:vopstats_zfs:write_bytes 255725992
# kstat -p ::vopstats_zfs:{nread,read_bytes,nwrite,write_bytes}
#
uhm, but:
kstat -p ::vopstats_zfs
[snip]
unix:0:vopstats_zfs:nwrite 24201307
unix:0:vopstats_zfs:read_bytes 1557032944566
unix:0:vopstats_zfs:readdir_bytes 129267
unix:0:vopstats_zfs:snaptime3281423.01228961
unix:0:vopstats_zfs:write_bytes 222641182203
what gives? This is:
SunOS wiggum.4amlunch.net 5.11 snv_81 i86pc i386 i86pc
-brian
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Re: [zfs-discuss] iostat and monitoring
On Sat, Jul 5, 2008 at 9:48 PM, Brian Hechinger [EMAIL PROTECTED] wrote:
On Sat, Jul 05, 2008 at 03:03:34PM -0500, Mike Gerdts wrote:
$ kstat -p ::vopstats_zfs:{nread,read_bytes,nwrite,write_bytes}
unix:0:vopstats_zfs:nread 418787
unix:0:vopstats_zfs:read_bytes612076305
unix:0:vopstats_zfs:nwrite163544
unix:0:vopstats_zfs:write_bytes 255725992
This was on a virtual machine with a 12 GB zpool (one virtual disk)
that had been up for a few days (but suspended most of the time). My
guess is that most of the activity my zpool was seeing was from the
swap device.
# kstat -p ::vopstats_zfs:{nread,read_bytes,nwrite,write_bytes}
#
uhm, but:
kstat -p ::vopstats_zfs
[snip]
unix:0:vopstats_zfs:nwrite 24201307
24 million write operations.
unix:0:vopstats_zfs:read_bytes 1557032944566
$ perl -e 'print (1557032944566 30)'
1450
Looks like you've read about 1.4 TB since boot.
unix:0:vopstats_zfs:readdir_bytes 129267
1.2 GB of readdir activity. Lots of files? Is someone doing find or
du through the area with lots of files?
unix:0:vopstats_zfs:snaptime3281423.01228961
unix:0:vopstats_zfs:write_bytes 222641182203
$ perl -e 'print (222641182203 30)'
207
207 MB of writes.
$ perl -e 'print 222641182203 / 24201307'
9199.55199952631
Average write size was a bit over 9 KB.
what gives? This is:
SunOS wiggum.4amlunch.net 5.11 snv_81 i86pc i386 i86pc
Do the numbers seem unreasonable for the size of the pool, the uptime
of the system, etc.? Remember my comments earlier about how you can
now see the reads (and readdirs) that came from cache and didn't do
physical I/O.
--
Mike Gerdts
http://mgerdts.blogspot.com/
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