RAID0 .. fail.

Hello all!

First post here, and ready to be told about all the stupid things I should have done (backup? no. raid0? yes. etc. etc.)

Long story short, the RAID0 setup was only supposed to be a temporary solution (and we all know how permanent they are .. until they fail! fnarr!), and consists of two disks.

One of them has failed (silly me didn't monitor the SMART health status -- "IMPENDING FAILURE TOO MANY BLOCK REASSIGNS"), and of course even if Linux is helpful enough to remount the file system RO when there is a failure

[15448.438426] sd 2:2:1:0: [sdb] tag#591 FAILED Result: hostbyte=DID_ERROR driverbyte=DRIVER_OK cmd_age=68s
[15448.438452] sd 2:2:1:0: [sdb] tag#591 CDB: Read(16) 88 00 00 00 00 01 6e 7a 49 a0 00 00 01 b8 00 00
[15448.438456] blk_update_request: I/O error, dev sdb, sector 6148475296 op 0x0:(READ) flags 0x80700 phys_seg 2
8 prio class 0                           
[15448.624313] sd 2:2:1:0: [sdb] tag#576 FAILED Result: hostbyte=DID_BAD_TARGET driverbyte=DRIVER_OK cmd_age=0s
[15448.624326] sd 2:2:1:0: [sdb] tag#576 CDB: Read(16) 88 00 00 00 00 01 6e 7a 49 a0 00 00 00 08 00 00
[15448.624330] blk_update_request: I/O error, dev sdb, sector 6148475296 op 0x0:(READ) flags 0x0 phys_seg 1 pri
o class 0
[15448.624910] megaraid_sas 0000:02:0e.0: scanning for scsi2...
[15448.624920] megaraid_sas 0000:02:0e.0: MR_DCMD_PD_LIST_QUERY not supported by firmware

nothing can be read from it since the adapter places the drive in a failed state as it should.

However, before I give up on all this, I am wondering if it is possible to (e.g. using MegaCLI) force the drive to be online even if there are errors.

It seemed to work until there were no errors (bringing it online from the BIOS, mount the fs RO) -- I rescued about 210G of data before there was another failure; but doing the boot + BIOS dance is a bit of a drag, so therefore this post.

(As an aside, but of really no relevance here except as a curiosity, MegaCLI reports no media errors, just "other errors" for this particular disk.)

Anyhow, thanks for reading!

Yours kindly,
Troy