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Old 03-14-2010, 04:59 AM   #1
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Access data on NTFS disk (Raid 5)

Hi there,

I am trying to access data that is on a Raid 5 array in Ubuntu... There are 4 installed disks (250gig disks) - 3 of which are setup as a Raid 5 array (the 4th is active but unused). These show up as one large drive (498gig).

I have had an issue with the drive where it is no longer allowing Windows to boot - I receive a disk read error on boot (so the OS does not load, obviously!) - what happened was basically I unplugged then replugged in one of the disks which affected the array... I physically reconnected everything as it was, I then had to 'reactivate' the disk in the Raid BIOS... at that point the array seemed OK, was the right size, etc (and was listed as "Optimal" in the Raid BIOS) however, the problem with the disk read error persists.

I have started the machine using Ubuntu v9.10 from a CD (non-destructive mode) and it shows a disk of the right size (ie: on the desktop and in Nautilus it says "498gig Filesystem" ). However, in Nautilus, the disk appears empty with no folders or files on it (even with hidden files shown).... If I view 'Information" for the disk it shows 67gig used space and 399gig free space (which is correct). Also, if I view the disk in Gparted, it shows a disk with about 67gig of used space and 399 free space on a 464gig disk (with 8gig unallocated).

One more thing.... when I try the command 'sudo dmraid -tay' it says that there is no raid disk (there are in fact, no drives plugged into IDE or SATA slots - all disk are plugged into the RAID controller card).

Anyway, at this stage, I just want to copy the data to a single hard disk if possible and move on.

Can anyone please advise on what I could try at this point. Hopefully, the data is not lost!

Thanks in advance for any help.

Old 03-14-2010, 05:32 AM   #2
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If the kernel recognized a raid partition, does it exist as a /dev/dm-0 (or /dev/dm-1, etc.) device. If so see if you can mount it.

Look through the boot messages and see what was printed when the raid was discovered. The dmraid command is for software raid arrays. It sounds like you are using hardware raid. Also look in /dev/mapper/.

You can use the "sudo file -s" command to examine devices. That will tell you if a filesystem is detected.
Old 03-14-2010, 10:28 AM   #3
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Thank you for the response...

I think the disk exists as sda1 (as opposed to dm-X). As I mentioned, it mounts, but does not display any files or folders (although the disk info appears correct)...

I tried 'sudo file -s' but I'm not sure if I did it correctly.... (it just brought up usage instructions....??)

Anyway, I have checked the boot messages (using dmesg), and have pasted an extract below (just in case it helps!).

Thanks again for your assistance...

[ 3.462894] e1000: eth1: e1000_probe: Intel(R) PRO/1000 Network Connection
[ 3.557592] scsi[2]: scanning scsi channel 1 [virtual] for logical drives
[ 3.557818] scsi 2:1:0:0: Direct-Access MegaRAID LD 0 RAID5 474G 814B PQ: 0 ANSI: 2
[ 3.562015] sd 2:1:0:0: Attached scsi generic sg1 type 0
[ 3.564586] sd 2:1:0:0: [sda] 972652544 512-byte logical blocks: (497 GB/463 GiB)
[ 3.564620] sd 2:1:0:0: [sda] Write Protect is off
[ 3.564626] sd 2:1:0:0: [sda] Mode Sense: 00 00 00 00
[ 3.564648] sd 2:1:0:0: [sda] Asking for cache data failed
[ 3.564653] sd 2:1:0:0: [sda] Assuming drive cache: write through
[ 3.564852] sd 2:1:0:0: [sda] Asking for cache data failed
[ 3.564857] sd 2:1:0:0: [sda] Assuming drive cache: write through
[ 3.564864] sda: sda1
[ 3.566370] sd 2:1:0:0: [sda] Asking for cache data failed
[ 3.566377] sd 2:1:0:0: [sda] Assuming drive cache: write through
[ 3.566383] sd 2:1:0:0: [sda] Attached SCSI disk
[ 4.154621] xor: automatically using best checksumming function: pIII_sse
[ 4.172508] pIII_sse : 4553.000 MB/sec
[ 4.172512] xor: using function: pIII_sse (4553.000 MB/sec)
[ 4.175740] device-mapper: dm-raid45: initialized v0.2594b
[ 5.973074] ISO 9660 Extensions: Microsoft Joliet Level 3
[ 6.005776] ISO 9660 Extensions: RRIP_1991A
[ 6.251316] aufs 2-standalone.tree-30-20090727
[ 6.488548] squashfs: version 4.0 (2009/01/31) Phillip Lougher
[ 63.985098] udev: starting version 147
[ 66.749628] intel_rng: FWH not detected


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