Ahmed, > Thanks for your informative reply. I am involved with kristof > (original poster) in the setup, please allow me to reply below > >> Was the follow 'test' run during resynchronization mode or >> replication >> mode? >> > > Neither, testing was done while in logging mode. This was chosen to > simply avoid any network "issues" and to get the setup working as fast > as possible. The setup was created with: > > sndradm -E pri /dev/zvol/rdsk/gold/myzvol /dev/rramdisk/ram1 sec > /dev/zvol/rdsk/gold/myzvol /dev/rramdisk/ram1 ip async > > Note that the logging disks are ramdisks again trying to avoid disk > contention and get fastest performance (reliability is not a concern > in this test). Before running the tests, this was the state > > #sndradm -P > /dev/zvol/rdsk/gold/myzvol <- pri:/dev/zvol/rdsk/gold/myzvol > autosync: off, max q writes: 4096, max q fbas: 16384, async threads: > 2, mode: async, state: logging > > While we should be getting minimal performance hit (hopefully), we got > a big performance hit, disk throughput was reduced to almost 10% of > the normal rate.
Is it possible to share information on your ZFS storage pool configuration, your testing tool, testing types and resulting data? I just downloaded Solaris Express CE (b105) http://opensolaris.org/os/downloads/sol_ex_dvd_1/ , configured ZFS in various storage pool types, SNDR with and without RAM disks, and I do not see that disk throughput was reduced to almost 10% o the normal rate. Yes there is some performance impact, but no where near there amount reported. There are various factors which could come into play here, but the most obvious reason that someone may see a serious performance degradation as reported, is that prior to SNDR being configured, the existing system under test was already maxed out on some system limitation, such as CPU and memory. I/O impact should not be a factor, given that a RAM disk is used. The addition of both SNDR and a RAM disk in the data, regardless of how small their system cost is, will have a profound impact on disk throughput. Jim > > Please feel free to ask for any details, thanks for the help > > Regards > _______________________________________________ > storage-discuss mailing list > storage-disc...@opensolaris.org > http://mail.opensolaris.org/mailman/listinfo/storage-discuss _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
