>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?
