I am not sure you can monitor actual mechanical seeks short of debugging and interrogating the HDD firmware - because it is the last responsible logic in the chain of caching, queuing and issuing actual commands to the disk heads.
For example, a long logical IO spanning several cylinders would probably be seen by the OS as one IO with many MBs of transfer, but would break down into track-to-track seeks in disk's reality. Nevertheless, as far as the OS commands are concerned, you can try to interpolate outputs of iostat and iopattern: http://www.richardelling.com/Home/scripts-and-programs-1/iopattern The latter tries to estimate the amounts of SEQuential and RNDom reads and writes in your workload. HTH, //Jim 2011-05-19 16:35, Sašo Kiselkov пишет:
Hi all, I'd like to ask whether there is a way to monitor disk seeks. I have an application where many concurrent readers (>50) sequentially read a large dataset (>10T) at a fairly low speed (8-10 Mbit/s). I can monitor read/write ops using iostat, but that doesn't tell me how contiguous the data is, i.e. when iostat reports "500" read ops, does that translate to 500 seeks + 1 read per seek, or 50 seeks + 10 reads, etc? Thanks! Regards, -- Saso _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
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