Messages in this thread | | | Date | Tue, 05 Jun 2007 00:31:32 -0400 | From | Marc Chiarini <> | Subject | Problem with /proc/diskstats on RHEL4 |
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Hi all,
Wondering if folks can help me out. I have been doing some collection of statistics on my Redhat boxes and have noted that the read values in /proc/diskstats *very* rarely change. Things like # of read requests, reads merged, #bytes read, total time spent reading, are just basically frozen for long periods of time. On 2 different physical machines running RHEL4 I have taken deltas directly from this file while performing large numbers of reads on local hard disks (such as zcat-ing every man page in /usr/share/man right after login). The write statistics show plenty of change over time, but not so for the read statistics. One machine has a 2.6.9-5 kernel running on a Dell P4 and is configured with software RAID across two IDE disks. Another machine (actually there are several virtually identical ones) has a 2.6.9-42 kernel running on x86_64 SMP, and is configured with several local SCSI disks (no LVM or RAID) and mounts several filesystems over NFS.
I know that /proc/diskstats works correctly on many machines, such as the Suse EL, FC6, and even RHEL 4AS (2.6.9-34) virtual machines I have running on VMWare Server. I have also witnessed it working in Xubuntu Feisty Fawn on several similarly configured physical boxes with P3s and SCSI disks.
If anyone knows of any bugs in diskstats (coming from the kernel side?), any conflicts with the hardware mentioned above, or can suggest any reason why this is occuring on a small subset of machines, please contact me. Also, if you are using RHEL4, perhaps you might take a moment to see if your own /proc/diskstats is progressing on reads, and drop me a line about your hardware/kernel configs?
Many thanks in advance for your much appreciated help!
Regards, Marc Chiarini
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