On Mon, Mar 6, 2017 at 9:26 AM, Olivier Swinkels
<olivier.swinkels@xxxxxxxxx> wrote:
> 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:
Correction: (Put the wrong ID in the pvcreate example):
pvcreate --uuid "DWv51O-lg9s-Dl4w-EBp9-QeIF-Vv60-8wt2uS" --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
