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Gareth's questions

Martin Hope
Gareth
Asked: 2013-06-07 05:30:09 +0800 CST
  • 11

My Ubuntu 12.04 system has two zpools: rpool (containing the root filesystem) and rdata (containing all other data). rdata was originally 2 x 1TB disks mirrored.

Because I couldn't upgrade rdata to 3TB disks (wrong ashift) I had to create a new zpool from the new 3TB disks: initially called datapool. I then rsync'd all the data across, exported rdata, imported datapool as rdata and Bob's your Uncle. I then powered off and removed the old disks. However...

When I powered back on, zpool status shows

  pool: rdata
 state: UNAVAIL
status: One or more devices could not be used because the label is missing 
    or invalid.  There are insufficient replicas for the pool to continue
functioning.
action: Destroy and re-create the pool from
    a backup source.
   see: http://zfsonlinux.org/msg/ZFS-8000-5E
  scan: none requested
config:

NAME                                                 STATE     READ WRITE CKSUM
rdata                                                UNAVAIL      0     0     0         insufficient replicas
  mirror-0                                           UNAVAIL      0     0     0  insufficient replicas
    scsi-SATA_WDC_WD10EADS-00_WD-WCAU47275172-part1  UNAVAIL      0     0     0
    scsi-SATA_WDC_WD10EADS-00_WD-WCAU47283913-part1  UNAVAIL      0     0     0

  pool: rpool
 state: ONLINE
  scan: scrub repaired 0 in 0h23m with 0 errors on Tue Jun  4 11:33:29 2013
config:

NAME                                 STATE     READ WRITE CKSUM
rpool                                ONLINE       0     0     0
  ata-Maxtor_6Y120L0_Y31J3CLE-part2  ONLINE       0     0     0

errors: No known data errors

As you can see, zpool status is still showing the old rdata; which is not available.

zpool import shows

   pool: rdata
     id: 7033445233439275442
  state: ONLINE
 action: The pool can be imported using its name or numeric identifier.
 config:

rdata                                   ONLINE
  mirror-0                              ONLINE
    scsi-SATA_ST3000DM001-1CH_W1F1EE1G  ONLINE
    scsi-SATA_ST3000DM001-1CH_W1F25SE2  ONLINE

This is the correct rdata

Question: How do I get Ubuntu to forget all about the old zpool?

zfs
Martin Hope
Gareth
Asked: 2013-06-04 04:49:09 +0800 CST
  • 2

I have Ubuntu 12.04 with ZFS installed. There are two pools: rpool (the root filesystem) and rdata (all the data). rdata was built with 2 x 1TB WD EADS drives (with 512 byte physical sectors) in a ZFS mirror. rdata has many datasets on it in a hierarchy.

rdata is running out of space so I have purchased 2 x Seagate 3TB drives. Unfortunately, when I tried to add one the the new drives to the mirror, so that it would resilver, zpool attach failed saying

cannot attach /dev/disk/by-id/scsi-SATA_ST3000DM001-1CH_W1F1EE1G-part1 to /dev/disk/by-id/scsi-SATA_WDC_WD10EADS-00_WD-WCAU47275172-part1: devices have different sector alignment

I now know this is because the new drives ave 4k physical sectors and the only recovery path is to rebuild the pool. I am proposing to do the following:

  1. Ensure there is a snapshot of all datasets on rdata.
  2. Remove 1 element of the rdata mirror (so I have a known good backup and to free up a SATA port)
  3. Connect one of the new drives to the machine
  4. create a new pool called rdata1 with 4k sectors and a single physical device
  5. use zpool recv to restore the snapshots of rdata's datasets to rdata1
    • At this point, rdata1 should be identical to rdata
  6. export the device on which rdata1 is located
  7. destroy rdata
  8. import the device that contained rdata1 as rdata
  9. remove the old physical disk and replace it with the other new disk
  10. attach the other new disk to the newly created rdata to re-create the mirror

Does this sound reasonable? I'll still have the second old disk if it goes wrong and as a final resort, I have another FreeNAS server that has a full backup of all the snapshots; just in case.

Gareth

hard-drive