Is this typical for these devices? Can I extrapolate these numbers linearly? For example, can I expect ~21 4MB sequential writes per second?
--- Todd Andrey Kuzmin wrote: > http://mtron.net/Upload_Data/Spec/ASiC/MOBI/SATA/MSD-SATA3535_rev0.3.pdf, > Sect. 3.3.1, Table 4, last row. > > Regards, > Andrey > > > > On Wed, Oct 15, 2008 at 9:10 PM, Eric Sproul <[EMAIL PROTECTED]> wrote: > >> Eric Sproul wrote: >> >>> zpool create data raidz c0t4d0 c0t5d0 c0t6d0 c0t7d0 log mirror c2d1 c3d1 >>> >> This box has 8 cores (2x quad-core Xeon) and 32GB RAM. >> >> We've been running Postgres 8.3 stress tests (pgbench), but we see some odd >> results. Looking at 'iostat -xn' we see what looks like a bottleneck on the >> ZIL >> devices: >> >> extended device statistics >> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device >> 0.0 102.0 0.0 6527.7 0.0 1.0 0.0 9.4 0 96 c2d1 >> 0.0 101.0 0.0 6399.7 0.0 1.0 0.0 9.5 0 95 c3d1 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c1t1d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t2d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t3d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t4d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t5d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t6d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t7d0 >> ` extended device statistics >> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device >> 0.0 102.0 0.0 5072.0 0.0 1.0 0.0 9.4 0 96 c2d1 >> 0.0 103.0 0.0 5200.0 0.0 0.9 0.0 9.0 0 92 c3d1 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c1t1d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t2d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t3d0 >> 0.0 55.0 0.0 1458.5 0.0 0.9 0.0 17.1 0 24 c0t4d0 >> 0.0 53.0 0.0 1458.5 0.0 0.8 0.0 15.8 0 24 c0t5d0 >> 0.0 57.0 0.0 1456.5 0.0 1.5 0.0 25.7 0 29 c0t6d0 >> 0.0 63.0 0.0 1438.0 0.0 1.1 0.0 17.3 0 22 c0t7d0 >> extended device statistics >> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device >> 0.0 101.0 0.0 5608.3 0.0 1.0 0.0 9.4 0 95 c2d1 >> 0.0 101.0 0.0 5608.3 0.0 1.0 0.0 9.4 0 95 c3d1 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c1t1d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t2d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t3d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t4d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t5d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t6d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t7d0 >> extended device statistics >> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device >> 0.0 102.0 0.0 6528.0 0.0 1.0 0.0 9.4 0 95 c2d1 >> 0.0 102.0 0.0 6528.0 0.0 0.9 0.0 9.0 0 92 c3d1 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c1t1d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t2d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t3d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t4d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t5d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t6d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t7d0 >> extended device statistics >> r/s w/s kr/s kw/s wait actv wsvc_t asvc_t %w %b device >> 0.0 100.0 0.0 6399.8 0.0 1.0 0.0 9.6 0 96 c2d1 >> 0.0 100.0 0.0 6399.8 0.0 1.0 0.0 9.6 0 96 c3d1 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c1t1d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t2d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t3d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t4d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t5d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t6d0 >> 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0 0 c0t7d0 >> >> We never see more than about 100 write ops/second on the SSDs, which seems >> really low to me, and it also seems odd that they are 95-96% utilized at that >> rate. The pgbench test is primarily doing updates with some percentage of >> inserts thrown in, and the entire database fits into RAM, which is why we see >> very little activity on the raidz disks, but lots on the ZIL, since there's a >> ton of fsync() from Postgres. >> >> I was expecting much higher IOPS on the SSDs. Can anyone help me understand >> what's going on here? >> >> Thanks, >> Eric >> _______________________________________________ >> storage-discuss mailing list >> [email protected] >> http://mail.opensolaris.org/mailman/listinfo/storage-discuss >> >> > _______________________________________________ > storage-discuss mailing list > [email protected] > http://mail.opensolaris.org/mailman/listinfo/storage-discuss > _______________________________________________ storage-discuss mailing list [email protected] http://mail.opensolaris.org/mailman/listinfo/storage-discuss
