nixCraft

hi ,

can anyone tell me how to check the RAID level(hardware) in redhat linux?. is there any command for the same?
pls help


regds,
harry.

Hi,

You need to use vendors tool to see information and configuring RAID. For example under Adaptec RAID card I use arcconf command to see information about RAID devices.

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is there any tool available for IBM serveRaid?? can you send me the link?

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Vivek | My personal blog
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Hi,

For hardware RAID , you can check using BIOS or any menu at the time of boot.
For software RAID , you can check /proc/mdstat

I think he wanted to see status without rebooting server, the only way to do is via command line.

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Vivek | My personal blog
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Here is some info i found on checking your raid levels. I haven't verified it yet, but I am going to. I was on the same mission as you are...lots of servers with different versions of raid.

#raiddev /dev/md0

and then check

#raiddev /dev/md1

You should get a list like this:

raiddev /dev/md0
raid-level 0
nr-raid-disks 2
persistent-superblock 0
chunk-size 8

device /dev/hda1
raid-disk 0
device /dev/hdb1
raid-disk 1

raiddev /dev/md1
raid-level 5
nr-raid-disks 3
nr-spare-disks 1
persistent-superblock 1
parity-algorithm left-symmetric

device /dev/sda1
raid-disk 0
device /dev/sdb1
raid-disk 1
device /dev/sdc1
raid-disk 2
device /dev/sdd1
spare-disk 0

In this scenario, it shows that md1 had raid 5 installed.


Here is more information on the directives which are in raid configuration files; the options are listen in this file in the same order they should appear in the actual configuration file.
raiddev device This introduces the configuration section for the stated device.
nr-raid-disks count Number of raid devices in the array; there should be count raid-disk entries later in the file. (current maximum limit for RAID devices -including spares- is 12 disks. This limit is already extended to 256 disks in experimental patches.)
nr-spare-disks count Number of spare devices in the array; there should be count spare-disk entries later in the file. Spare disks may only be used with RAID4 and RAID5, and allow the kernel to automatically build new RAID disks as needed. It is also possible to add/remove spares runtime via raidhotadd/raidhotremove, care has to be taken that the /etc/raidtab configuration exactly follows the actual configuration of the array. (raidhotadd/raidhotremove does not change the configuration file)
persistent-superblock 0/1 newly created RAID arrays should use a persistent superblock. A persistent superblock is a small disk area allocated at the end of each RAID device, this helps the kernel to safely detect RAID devices even if disks have been moved between SCSI controllers. It can be used for RAID0/LINEAR arrays too, to protect against accidental disk mixups. (the kernel will either correctly reorder disks, or will refuse to start up an array if something has happened to any member disk. Of course for the 'fail-safe' RAID variants (RAID1/RAID5) spares are activated if any disk fails.)
Every member disk/partition/device has a superblock, which carries all information necessary to start up the whole array. (for autodetection to work all the 'member' RAID partitions should be marked type 0xfd via fdisk) The superblock is not visible in the final RAID array and cannot be destroyed accidentally through usage of the md device files, all RAID data content is available for filesystem use.
parity-algorithm which The parity-algorithm to use with RAID5. It must be one of left-asymmetric, right-asymmetric, left-symmetric, or right-symmetric. left-symmetric is the one that offers maximum performance on typical disks with rotating platters.
chunk-size size Sets the stripe size to size kilobytes. Has to be a power of 2 and has a compilation-time maximum of 4M. (MAX_CHUNK_SIZE in the kernel driver) typical values are anything from 4k to 128k, the best value should be determined by experimenting on a given array, alot depends on the SCSI and disk configuration.
device devpath Adds the device devpath to the list of devices which comprise the raid system. Note that this command must be followed by one of raid-disk, spare-disk, or parity-disk. Also note that it's possible to recursively define RAID arrays, ie. to set up a RAID5 array of RAID5 arrays. (thus achieving two-disk failure protection, at the price of more disk space spent on RAID5 checksum block
raid-disk index The most recently defined device is inserted at position index in the raid array.
spare-disk index The most recently defined device is inserted at position index in the spare disk array.
parity-disk index The most recently defined device is moved to the end of the raid array, which forces it to be used for parity.
failed-disk index The most recently defined device is inserted at position index in the raid array as a failed device. This allows you to create raid 1/4/5 devices in degraded mode - useful for installation. Don't use the smallest device in an array for this, put this after the raid-disk definitions! Hope it works.