Thanks for looking into this. Doesn't seem like there's much low-hanging fruit to make compaction faster but I'll keep that in the back of my mind.
-Jonathan On Thu, Dec 3, 2009 at 4:58 PM, Freeman, Tim <[email protected]> wrote: >>So this is working as designed, but the design is poor because it >>causes confusion. If you can open a ticket for this that would be >>great. > > Done, see: > > https://issues.apache.org/jira/browse/CASSANDRA-599 > >>What does iostat -x 10 (for instance) say about the disk activity? > > rkB/s is consistently high, and wkB/s varies. This is a typical entry with > wkB/s at the high end of its range: > >>avg-cpu: %user %nice %sys %iowait %idle >> 1.52 0.00 1.70 27.49 69.28 >> >>Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s >>avgrq-sz avgqu-sz await svctm %util >>sda 3.10 3249.25 124.08 29.67 26299.30 26288.11 13149.65 13144.06 >>342.04 17.75 92.25 5.98 91.92 >>sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 >>0.00 0.00 0.00 0.00 0.00 >>sda2 3.10 3249.25 124.08 29.67 26299.30 26288.11 13149.65 13144.06 >>342.04 17.75 92.25 5.98 91.92 >>sda3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 >>0.00 0.00 0.00 0.00 0.00 > > and at the low end: > >>avg-cpu: %user %nice %sys %iowait %idle >> 1.50 0.00 1.77 25.80 70.93 >> >>Device: rrqm/s wrqm/s r/s w/s rsec/s wsec/s rkB/s wkB/s >>avgrq-sz avgqu-sz await svctm %util >>sda 3.40 817.10 128.60 17.70 27828.80 6600.00 13914.40 3300.00 >>235.33 6.13 56.63 6.21 90.81 >>sda1 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 >>0.00 0.00 0.00 0.00 0.00 >>sda2 3.40 817.10 128.60 17.70 27828.80 6600.00 13914.40 3300.00 >>235.33 6.13 56.63 6.21 90.81 >>sda3 0.00 0.00 0.00 0.00 0.00 0.00 0.00 0.00 >>0.00 0.00 0.00 0.00 0.00 > > Tim Freeman > Email: [email protected] > Desk in Palo Alto: (650) 857-2581 > Home: (408) 774-1298 > Cell: (408) 348-7536 (No reception business hours Monday, Tuesday, and > Thursday; call my desk instead.) > > > -----Original Message----- > From: Jonathan Ellis [mailto:[email protected]] > Sent: Thursday, December 03, 2009 2:45 PM > To: [email protected] > Subject: Re: Persistently increasing read latency > > On Thu, Dec 3, 2009 at 4:34 PM, Freeman, Tim <[email protected]> wrote: >>>Can you tell if the system is i/o or cpu bound during compaction? >> >> It's I/O bound. It's using ~9% of 1 of 4 cores as I watch it, and all it's >> doing right now is compactions. > > What does iostat -x 10 (for instance) say about the disk activity? >
