On Sun, Mar 5, 2017 at 7:55 PM, Phil Turmel <philip@xxxxxxxxxx> wrote:
>
> On 03/03/2017 04:35 PM, Olivier Swinkels wrote:
> > Hi,
> >
> > I'm in quite a pickle here. I can't recover from a disk failure on my
> > 6 disk raid 5 array.
> > Any help would really be appreciated!
> >
> > Please bear with me as I lay out the the steps that got me here:
>
> [trim /]
>
> Well, you've learned that mdadm --create is not a good idea. /-:
>
> However, you did save your pre-re-create --examine reports, and it
> looks like you've reconstructed correctly. (Very brief look.)
>
> However, you discovered that mdadm's defaults have long since changed
> to v1.2 superblock, 512k chunks, bitmaps, and a substantially different
> metadata layout. In fact, I'm certain your LVM metadata has been
> damaged by the brief existence of mdadm's v1.2 metadata on your member
> devices. Including removal of the LVM magic signature.
>
> What you need is a backup of your lvm configuration, which is commonly
> available in /etc/ of an install, but naturally not available if /etc/
> was inside this array. In addition, though, LVM generally writes
> multiple copies of this backup in its metadata. And that is likely
> still there, near the beginning of your array.
>
> You should hexdump the first several megabytes of your array looking for
> LVM's XML formatted configuration. If you can locate some of those
> copies, you can probably use dd to extract a copy to a file, then use
> that with LVM's recovery tools to re-establish all of your LVs.
>
> There is a possibilility that some of your actual LV content was damaged
> by the mdadm v1.2 metadata, too, but first recover the LVM setup.
>
> Phil
That sounds promising, as /etc was not on the array.
I found a backup in /etc/lvm/backup/lvm-raid (contents shown below).
Unfortunatelly when I try to use it to restore the LVM I get the
following error:
vgcfgrestore -f /etc/lvm/backup/lvm-raid lvm-raid
Aborting vg_write: No metadata areas to write to!
Restore failed.
So I guess I also need to recreate the physical volume using:
pvcreate --uuid "0Esja8-U0EZ-fndQ-vjUq-oIuX-3KgA-uTL6rP" --restorefile
/etc/lvm/backup/lvm-raid
Is this correct? (I'm a bit hesitant with another 'create' command as
you might understand.)
Regards,
Olivier
===============================================================================
/etc/lvm/backup/lvm-raid
===============================================================================
# Generated by LVM2 version 2.02.133(2) (2015-10-30): Fri Oct 14 15:55:36 2016
contents = "Text Format Volume Group"
version = 1
description = "Created *after* executing 'vgcfgbackup'"
creation_host = "horus-server" # Linux horus-server 3.13.0-98-generic
#145-Ubuntu SMP Sat Oct 8 20:13:07 UTC 2016 x86_64
creation_time = 1476453336 # Fri Oct 14 15:55:36 2016
lvm-raid {
id = "0Esja8-U0EZ-fndQ-vjUq-oIuX-3KgA-uTL6rP"
seqno = 8
format = "lvm2" # informational
status = ["RESIZEABLE", "READ", "WRITE"]
flags = []
extent_size = 524288 # 256 Megabytes
max_lv = 0
max_pv = 0
metadata_copies = 0
physical_volumes {
pv0 {
id = "DWv51O-lg9s-Dl4w-EBp9-QeIF-Vv60-8wt2uS"
device = "/dev/md0" # Hint only
status = ["ALLOCATABLE"]
flags = []
dev_size = 19535144448 # 9.09676 Terabytes
pe_start = 512
pe_count = 37260 # 9.09668 Terabytes
}
}
logical_volumes {
lvm0 {
id = "OpWRpy-O4JT-Ua3t-E1A4-2SuN-GLLR-5CFMLh"
status = ["READ", "WRITE", "VISIBLE"]
flags = []
segment_count = 1
segment1 {
start_extent = 0
extent_count = 37260 # 9.09668 Terabytes
type = "striped"
stripe_count = 1 # linear
stripes = [
"pv0", 0
]
}
}
}
}
--
To unsubscribe from this list: send the line "unsubscribe linux-raid" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
