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Thread: sar: how to trunslate an output

  1. #1

    Default sar: how to trunslate an output

    Hi all
    I want to use sar -d to monitor disk activity.
    Here is what I get:
    Average: dev8-176 7.97 597.67 33.55
    Average: dev8-192 1.33 1.33 0.66
    Average: dev8-208 2.33 1.33 32.56
    Average: dev8-224 2.33 1.33 32.56
    Average: dev8-240 4.32 512.62 1.66
    Average: dev65-0 4.32 512.62 1.66
    Average: dev65-16 1.33 1.33 0.66
    Average: dev65-32 1.33 1.33 0.66
    Average: dev65-48 0.00 0.00 0.00
    Average: dev65-64 0.00 0.00 0.00
    Average: dev253-0 0.33 0.00 2.66
    Average: dev253-1 0.00 0.00 0.00

    Output from df -k:

    /dev/mapper/VolGroup00-LogVol00
    15126920 5848124 8510388 41% /
    /dev/cciss/c0d0p1 101086 26152 69715 28% /boot
    none 1977060 0 1977060 0% /dev/shm
    /dev/mapper/VolGroup00-LogVol02
    30964668 19036740 10669988 65% /u01
    /dev/sdl1 104856160 42419680 62436480 41% /u09
    /dev/sdm1 8388544 1818844 6569700 22% /u10
    /dev/sdn1 8388544 2064736 6323808 25% /u11


    How to relate entries from first output to devices which I know and see in df -k output?

    Thank you, Gene.

  2. #2
    Join Date
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    Default Re: sar: how to trunslate an output

    Hi,

    Use the content of /proc/partitions file to map the entries.

    Also, run ls -l on every disk device and you'll get the major and minor number for the device node corresponding to the partition.

    This should do the trick.

    Hope this helps.

    Regards.

  3. #3

    Default Re: sar: how to trunslate an output

    Thank you for your respond.
    I am still having problems using sar.
    /proc/partitions do not shed any light on sar output.
    Here is the contents of it.
    I see similar entries in this file and df -k. But sar output does not show any of them.
    ls -l on each /dev file only shows when entries in /dev were created.

    cat /proc/partitions:

    104 0 71126640 cciss/c0d0
    104 1 104391 cciss/c0d0p1
    104 2 71015332 cciss/c0d0p2
    8 0 1048576 sda
    8 1 20740 sda1
    8 2 1026630 sda2
    8 16 1048576 sdb
    8 17 20740 sdb1
    8 18 1026630 sdb2
    8 32 1048576 sdc
    8 33 20740 sdc1
    8 34 1026630 sdc2
    8 48 8388608 sdd
    8 49 8388592 sdd1
    8 64 8388608 sde
    8 65 8388592 sde1
    8 80 52428800 sdf
    8 81 52428784 sdf1
    8 96 52428800 sdg
    8 97 52428784 sdg1
    8 112 20971520 sdh
    8 113 20971504 sdh1
    8 128 52428800 sdi
    8 129 52428784 sdi1
    8 144 1048576 sdj
    8 145 1048343 sdj1
    8 160 1048576 sdk
    8 161 1048343 sdk1
    8 176 104857600 sdl
    8 177 104856191 sdl1
    8 192 8388608 sdm
    8 193 8388544 sdm1
    8 208 8388608 sdn
    8 209 8388544 sdn1
    8 224 52428800 sdo
    8 225 52428736 sdo1
    8 240 52428800 sdp
    8 241 52428736 sdp1
    65 0 52428800 sdq
    65 1 52428736 sdq1
    65 16 104857600 sdr
    65 32 104857600 sds
    65 48 209715200 sdt
    65 64 209715200 sdu
    253 0 15368192 dm-0
    253 1 8388608 dm-1
    253 2 31457280 dm-2
    120 144 20971520 emcpowerj
    120 145 20971504 emcpowerj1
    120 128 52428800 emcpoweri
    120 129 52428784 emcpoweri1
    120 256 1048576 emcpowerq
    120 257 20740 emcpowerq1
    120 258 1026630 emcpowerq2
    120 240 1048576 emcpowerp
    120 241 20740 emcpowerp1
    120 242 1026630 emcpowerp2
    120 224 1048576 emcpowero
    120 225 20740 emcpowero1
    120 226 1026630 emcpowero2
    120 208 8388608 emcpowern
    120 209 8388592 emcpowern1
    120 192 8388608 emcpowerm
    120 193 8388592 emcpowerm1
    120 176 52428800 emcpowerl
    120 177 52428784 emcpowerl1
    120 160 52428800 emcpowerk
    120 161 52428784 emcpowerk1
    120 112 8388608 emcpowerh
    120 113 8388544 emcpowerh1
    120 80 1048576 emcpowerf
    120 81 1048343 emcpowerf1
    120 272 104857600 emcpowerr
    120 320 209715200 emcpoweru
    120 96 52428800 emcpowerg
    120 97 52428736 emcpowerg1
    120 16 52428800 emcpowerb
    120 17 52428736 emcpowerb1

  4. #4
    Join Date
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    Default Re: sar: how to trunslate an output

    Hi,

    Let me make it clear.

    If you want to know the device name corresponding to the one displayed in the sar output, you only have to match the major and minor node numbers in sar list to the corresponding entry in /proc/partitions.

    The ls -l ouput also gives you those numbers, which are essential to identify the device node linux uses to address every device. You only have to use them in the /proc/partitions output to find out the device name.

    For example, according to the sar output listing you attached in your first post, you have a device managed by the device mapper that is referenced in sar output by the name dev253-1. That means that the major number is 253 (corresponding to devices managed the the device mapper software layer) and the minor is 1, sequential number used to identify the specific device managed by the same driver.
    You now go to the /proc/partitions file and find out from there that the device name corresponding to the sar entry is dm-1. This is the low level internal name used by the device mapper driver. To find out the high level name used in /etc/fstab corresponding to the dm-1 you go to /dev/mapper directory and run ls -l.
    There you will see the high level device name to the right and instead of sizing data you will find the device major and minor nodes.
    Thats it.
    I see you are using file systems located in luns defined in external storage devices (san), but that fact doesnt change the linux way of assigning them a device node and a device name.

    FYI: The /dev/disk directory hierarchy contains several subdirectories that list all the disk devices (disks and partitions) the kernel has currently recognized in your system. You can reference them using several approaches:
    -label
    -uuid
    -path
    -id

    Also, keep in mind that sar -d gives statistic data for every block device the kernel knows about, independently of the driver managing them. In other words, if you have set up LVM LVs out of PVs defined on physical partitions located in local or remote disks/luns, you will find sar statistics for the LVs, for the physical partitions and for the physical disk/lun as a whole.
    To ease the reading of sar ouput, filter it through grep.

    On the other side, if you are interested in knowing the exact meaning of every statistic datum displayed in every sar entry, read the manual pages. They are explained with full details there.

    Hope this helps.

    Regards.

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