HI, Gentooers!
So, I typed dd if=/dev/zero of=/dev/sd<wrong letter>, and despite
hitting ctrl-c quite quickly, zeroed out some portion of the initial
part of a disk. Which did this to my zfs raidz3 array:
NAME STATE READ WRITE CKSUM
zfs DEGRADED 0 0 0
raidz3-0 DEGRADED 0 0 0
ata-HGST_HUS724030ALE640_PK1234P8JJJVKP ONLINE 0 0 0
ata-HGST_HUS724030ALE640_PK1234P8JJP3AP ONLINE 0 0 0
ata-ST4000NM0033-9ZM170_Z1Z80P4C ONLINE 0 0 0
ata-ST4000NM0033-9ZM170_Z1ZAZ8F1 ONLINE 0 0 0
14296253848142792483 UNAVAIL 0 0
0 was /dev/disk/by-id/ata-ST4000NM0033-9ZM170_Z1ZAZDJ0-part1
ata-ST4000NM0033-9ZM170_Z1Z80KG0 ONLINE 0 0 0
Could have been worse. I do have backups, and it is raid3, so all
I've injured is my pride, but I do want to fix things. I'd
appreciate some guidance before I attempt doing this - I have no
experience at it myself.
The steps I envision are
1) zpool offline zfs 14296253848142792483 (What's that number?)
2) do something to repair the damaged disk
3) zpool online zfs <repaired disk>
Right now, the device name for the damaged disk is /dev/sda. Gdisk
says this about it:
Caution: invalid main GPT header, but valid backup; regenerating main header
from backup!
Warning: Invalid CRC on main header data; loaded backup partition table.
Warning! Main and backup partition tables differ! Use the 'c' and 'e' options
on the recovery & transformation menu to examine the two tables.
Warning! Main partition table CRC mismatch! Loaded backup partition table
instead of main partition table!
Warning! One or more CRCs don't match. You should repair the disk!
Main header: ERROR
Backup header: OK
Main partition table: ERROR
Backup partition table: OK
Partition table scan:
MBR: not present
BSD: not present
APM: not present
GPT: damaged
Found invalid MBR and corrupt GPT. What do you want to do? (Using the
GPT MAY permit recovery of GPT data.)
1 - Use current GPT
2 - Create blank GPT
Your answer: ( I haven't given one yet)
I'm not exactly sure what this is telling me. But I'm guessing it
means that the main partition table is gone, but there's a good
backup. In addition, some, but not all disk id info is gone:
1) /dev/disk/by-id still shows ata-ST4000NM0033-9ZM170_Z1ZAZDJ0 (the
damaged disk) but none of its former partitions
2) /dev/disk/by-partlabel shows entries for the undamaged disks in the
pool, but not the damaged one
3) /dev/disk/by-partuuid similar to /dev/disk/by-partlabel
4) /dev/disk/by-uuid does not show the damaged disk
This particular disk is from a batch of 4 I bought with the same make
and specification and very similar ids (/dev/disk/by-id). Can I
repair this disk by copying something off one of those other disks
onto this one? Is repair just repartitioning - as in the Gentoo
handbook? Is it as simple as running gdisk and typing 1 to accept
gdisk's attempt at recovering the gpt? Is running gdisk's recovery
and transformation facilities the way to go (the b option looks like
it's made for exactly this situation)?
Anybody experienced at this and willing to guide me?
Thanks,
John Blinka
