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I have a single hard drive that the OS is installed on and I have Sil raid card installed with two matching 500GB hdds set up in Raid 0 and formatted- they're completely empty. For whatever reason they are showing up as /dev/sdb and /dev/sdc and not as a single hard drive. I used fdisk to format both raid drives as Linux raid auto (fd) but I cannot mount either device and dmraid doesn't seem to want to work, what step am I missing?

When I installed 9.04 oh so long ago it seems like it recognized and automatically did everything that needed to be done, now I'm stuck.

dmraid Output

root@tripoli:~# dmraid -r

/dev/sdc: sil, "sil_biaebhadcfcb", stripe, ok, 976771072 sectors, data@ 0
/dev/sdb: sil, "sil_biaebhadcfcb", stripe, ok, 976771072 sectors, data@ 0

root@tripoli:~# dmraid -ay

RAID set "sil_biaebhadcfcb" already active

fdisk Output

root@tripoli:~# fdisk -l

Disk /dev/sda: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x000b9b01

   Device Boot      Start         End      Blocks   Id  System
/dev/sda1   *           1          32      248832   83  Linux
Partition 1 does not end on cylinder boundary.
/dev/sda2              32       60802   488134657    5  Extended
/dev/sda5              32       60802   488134656   8e  Linux LVM

Disk /dev/sdb: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0x6ead5c9a

   Device Boot      Start         End      Blocks   Id  System
/dev/sdb1               1       60801   488384001   fd  Linux raid autodetect

Disk /dev/sdc: 500.1 GB, 500107862016 bytes
255 heads, 63 sectors/track, 60801 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Sector size (logical/physical): 512 bytes / 512 bytes
I/O size (minimum/optimal): 512 bytes / 512 bytes
Disk identifier: 0xe6e2af28

   Device Boot      Start         End      Blocks   Id  System
/dev/sdc1               1       60801   488384001   fd  Linux raid autodetect
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1 Answer 1

You are using dmraid / fakeraid - for that you should not format the underlying drives, but the resulting fakeraid device. You may have damaged the BIOS metdata by partitioning the underlying drives so:

  • Use your BIOS to break and reinitialise the raid set
  • partition the raid set - it will be something like /dev/sil_biaebhadcfcb0 or /dev/mapper/sil_biaebhadcfcb0
  • Install onto the partitions you have created.

What you've appeared to have done is created two RAID super blocks, one on the raw disk and on the partition.

/dev/sdc: sil, "sil_biaebhadcfcb", stripe, ok, 976771072 sectors, data@ 0
/dev/sdb: sil, "sil_biaebhadcfcb", stripe, ok, 976771072 sectors, data@ 0

Says it's using the raw disk, the dmraid is actually working, problem is you have a extra data lying around which might give you a bad day if one of the drives is marginalized, like the first superblock becomes unreadable and dmraid happily scans the the second one, tries to repair it with the partner, which is still using the whole disk, and now you've got a size mismatch.

If it were, me, I would wipe everything out and start over. I don't have a ready solution that will remove the superblock from the partitioned space without running the risk of harming the superblock on the raw disk.

Did the documentation you followed not mention that the expected result of this operation is a new block device in /dev/mapper?

A "low level" format can be achieved by dd if=/dev/zero of=/dev/sdX

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Those drives are actually formated correctly, device-mapper takes those drives, examines the meta-data and creates a new map which lives in /dev/mapper, that's the device you want to work with, not the low level members. This would be true of md-raid too. –  ppetraki Apr 12 '12 at 13:53
    
Thats totally correct, but you miss the point that the original poster has separately fdisked the underlying drives, which can mess both mdraid and dmraid up - for instance, the partition size will be the full disk and not be excluding the raid metadata area. (which can be in different places depending on the exact BIOS in used for dmraid) –  lifeless Apr 21 '12 at 23:31
    
Nah, I just didn't see a reason at the time to elaborate on why it's broken as I have no solution to undo what he's done. If he followed my directions to begin with he would be OK. –  ppetraki Apr 22 '12 at 14:16

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