what are cciss devices? - Redhat

This is a discussion on what are cciss devices? - Redhat ; real dumbo question here - apologies in advance! I've googled to no avail... I'm seeking some numpty giude to what a cciss device is... e.g. I can see that some systems have hard drives / dev/sda, /dev/sdb etc... but then ...

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  1. what are cciss devices?

    real dumbo question here - apologies in advance!

    I've googled to no avail... I'm seeking some numpty giude to what a
    cciss device is... e.g. I can see that some systems have hard drives /
    dev/sda, /dev/sdb etc... but then also /dev/cciss/c0d0 or /dev/cciss/
    c0d1 etc...

    these cciss devices do not show in fdisk -l... so where do they come
    from?

    I presumed SAN but from what I can find SAN disks shoud get presented
    as a scsi disk eg /dev/sdc or whatever ..

    just trying to learn!

    cheers

    ian


  2. Re: what are cciss devices?

    .... perhaps a better questiion might be why can I see just three sd
    devices with fdisk -l, bjut 5 disk devices including two cciss devices
    with lvmdiskscan?

    (I have now found that the cciss devices are compaq raid devices :-)

    # fdisk -l

    Disk /dev/sda: 107.3 GB, 107372544000 bytes
    255 heads, 63 sectors/track, 13053 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot Start End Blocks Id System
    /dev/sda1 1 13053 104848191 83 Linux

    Disk /dev/sdb: 53.6 GB, 53686272000 bytes
    255 heads, 63 sectors/track, 6526 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot Start End Blocks Id System
    /dev/sdb1 1 6526 52420063+ 83 Linux

    Disk /dev/sdc: 53.6 GB, 53686272000 bytes
    255 heads, 63 sectors/track, 6526 cylinders
    Units = cylinders of 16065 * 512 = 8225280 bytes

    Device Boot Start End Blocks Id System
    /dev/sdc1 1 6526 52420063+ 83 Linux


    ]# lvmdiskscan
    lvmdiskscan -- reading all disks / partitions (this may take a
    while...)
    lvmdiskscan -- /dev/sda1 [ 99.99 GB] free whole disk
    lvmdiskscan -- /dev/sdb1 [ 49.99 GB] free whole disk
    lvmdiskscan -- /dev/sdc1 [ 49.99 GB] free whole disk
    lvmdiskscan -- /dev/cciss/c0d0p1 [ 99.59 MB] free whole disk
    lvmdiskscan -- /dev/cciss/c0d1p1 [ 23.84 GB] free whole disk
    lvmdiskscan -- 5 disks
    lvmdiskscan -- 5 whole disks
    lvmdiskscan -- 0 loop devices
    lvmdiskscan -- 0 multiple devices
    lvmdiskscan -- 0 network block devices
    lvmdiskscan -- 24 partitions
    lvmdiskscan -- 0 LVM physical volume partitions


  3. Re: what are cciss devices?

    sorry ... you can tell its Friday!

    System is RedHat ES 3


  4. Re: what are cciss devices?

    didds wrote:
    > ... perhaps a better questiion might be why can I see just three sd
    > devices with fdisk -l, bjut 5 disk devices including two cciss devices
    > with lvmdiskscan?


    > ]# lvmdiskscan
    > lvmdiskscan -- reading all disks / partitions (this may take a
    > while...)
    > lvmdiskscan -- /dev/sda1 [ 99.99 GB] free whole disk
    > lvmdiskscan -- /dev/sdb1 [ 49.99 GB] free whole disk
    > lvmdiskscan -- /dev/sdc1 [ 49.99 GB] free whole disk
    > lvmdiskscan -- /dev/cciss/c0d0p1 [ 99.59 MB] free whole disk
    > lvmdiskscan -- /dev/cciss/c0d1p1 [ 23.84 GB] free whole disk
    > lvmdiskscan -- 5 disks
    > lvmdiskscan -- 5 whole disks
    > lvmdiskscan -- 0 loop devices
    > lvmdiskscan -- 0 multiple devices
    > lvmdiskscan -- 0 network block devices
    > lvmdiskscan -- 24 partitions
    > lvmdiskscan -- 0 LVM physical volume partitions
    >


    It sounds like fdisk is returning only physical devices, while
    lvmdiskscan is returning both your physical devices, and logical RAID
    devices. The cciss/c0d0p1 and cciss/c0d1p1 references are to:
    controller0, disk0, partition1 and controller0, disk1, partition1.


    James http://cronus.ath.cx

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