I appear to have 2 (of 5) drives in my RAID-5 that are in the process
of failing. After one of the drives was removed from the array, I
reassembled and it initiated a rebuild. While the rebuild process was
running (or possibly when it was complete), there were read errors/bad
sectors on a second drive and the OS marked it as failed.
I'd like to get the array operational enough to copy whatever data
exists onto a new external NAS. I'd rather not have to invest in a
replacement drive.
I'm pretty sure I can --assemble --force and have a working array
(though probably with some corruption), but what I don't know is how
to copy the data off and force the kernel to ignore I/O errors (that
is, not take the array off-line during the process do to read errors).
Rather than replacing drives for the array, I'd like to transfer
whatever data is intact over to an external NAS. I can live with data
corruption, since the data is available off-site, but it would be nice
to rescue the bulk of the data and only have to restore what gets
corrupted rather than transferring all of the data over my Internet
connection.
I appreciate any help you can give. For completeness, here is a copy
of mdadm --examine /dev/sd[abcde]1:
/dev/sda1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : e6ebf415:39a410b6:e31b6a66:14144d11
Name : io:1 (local to host io)
Creation Time : Thu Sep 5 11:45:52 2013
Raid Level : raid5
Raid Devices : 5
Avail Dev Size : 2930012160 (1397.14 GiB 1500.17 GB)
Array Size : 5858846720 (5587.43 GiB 5999.46 GB)
Used Dev Size : 2929423360 (1396.86 GiB 1499.86 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 57726c49:5d4905bb:b397782e:710280ec
Update Time : Tue Jan 7 14:41:09 2014
Checksum : 3f8c5210 - correct
Events : 562642
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 0
Array State : A.AA. ('A' == active, '.' == missing)
/dev/sdb1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : e6ebf415:39a410b6:e31b6a66:14144d11
Name : io:1 (local to host io)
Creation Time : Thu Sep 5 11:45:52 2013
Raid Level : raid5
Raid Devices : 5
Avail Dev Size : 2930012160 (1397.14 GiB 1500.17 GB)
Array Size : 5858846720 (5587.43 GiB 5999.46 GB)
Used Dev Size : 2929423360 (1396.86 GiB 1499.86 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 3695aadc:5e666ce5:948e6903:45aa3b75
Update Time : Tue Jan 7 14:41:09 2014
Checksum : 5ade30aa - correct
Events : 562642
Layout : left-symmetric
Chunk Size : 512K
Device Role : spare
Array State : A.AA. ('A' == active, '.' == missing)
/dev/sdc1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : e6ebf415:39a410b6:e31b6a66:14144d11
Name : io:1 (local to host io)
Creation Time : Thu Sep 5 11:45:52 2013
Raid Level : raid5
Raid Devices : 5
Avail Dev Size : 2930012160 (1397.14 GiB 1500.17 GB)
Array Size : 5858846720 (5587.43 GiB 5999.46 GB)
Used Dev Size : 2929423360 (1396.86 GiB 1499.86 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 0eede877:ace15d39:a1c72cdb:bedd8153
Update Time : Tue Jan 7 14:41:09 2014
Checksum : 177053 - correct
Events : 562642
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 2
Array State : A.AA. ('A' == active, '.' == missing)
/dev/sdd1:
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : e6ebf415:39a410b6:e31b6a66:14144d11
Name : io:1 (local to host io)
Creation Time : Thu Sep 5 11:45:52 2013
Raid Level : raid5
Raid Devices : 5
Avail Dev Size : 2929424384 (1396.86 GiB 1499.87 GB)
Array Size : 5858846720 (5587.43 GiB 5999.46 GB)
Used Dev Size : 2929423360 (1396.86 GiB 1499.86 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 9081f762:29ea8ace:ae4924f0:38db4aff
Update Time : Tue Jan 7 14:41:09 2014
Checksum : 410a94de - correct
Events : 562642
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 3
Array State : A.AA. ('A' == active, '.' == missing)
Magic : a92b4efc
Version : 1.2
Feature Map : 0x0
Array UUID : e6ebf415:39a410b6:e31b6a66:14144d11
Name : io:1 (local to host io)
Creation Time : Thu Sep 5 11:45:52 2013
Raid Level : raid5
Raid Devices : 5
Avail Dev Size : 2929424384 (1396.86 GiB 1499.87 GB)
Array Size : 5858846720 (5587.43 GiB 5999.46 GB)
Used Dev Size : 2929423360 (1396.86 GiB 1499.86 GB)
Data Offset : 262144 sectors
Super Offset : 8 sectors
State : clean
Device UUID : 4eb7c2a6:bb0fd1c3:6621ff4c:c900a8d3
Update Time : Tue Jan 7 11:42:10 2014
Checksum : ab54c372 - correct
Events : 562622
Layout : left-symmetric
Chunk Size : 512K
Device Role : Active device 4
Array State : AAAAA ('A' == active, '.' == missing)
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