Tom Duell wrote On 12/12/06 17:11,:
Group, We are running a benchmark with 4000 users simulating a hospital management system running on Solaris 10 6/06 on USIV+ based SunFire 6900 with 6540 storage array. Are there any tools for measuring internal ZFS activity to help us understand what is going on during slowdowns?
dtrace can be used in numerous ways to examine every part of ZFS and Solaris. lockstat(1M) (which actually uses dtrace underneath) can also be used to see the cpu activity (try lockstat -kgIW -D 20 sleep 10). You can also use iostat (eg iostat -xnpcz) to look at disk activity.
We have 192GB of RAM and while ZFS runs well most of the time, there are times where the system time jumps up to 25-40% as measured by vmstat and iostat. These times coincide with slowdowns in file access as measured by a side program that simply reads a random block in a file... these response times can exceed 1 second or longer.
ZFS commits transaction groups every 5 seconds. I suspect this flurry of activity is due to that. Commiting can indeed take longer than a second. You might be able to show this by changing it with: # echo txg_time/W 10 | mdb -kw then the activity should be longer but less frequent. I don't however recommend you keep it at that value.
Any pointers greatly appreaciated! Tom ------------------------------------------------------------------------ _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
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