On 2013/09/04 9:47 AM, "Kit Westneat" <kwestneat@ddn.com> wrote:

>You should do that in order to get a clean image. If you don't, then you
>are more likely to get an inconsistent image. Of course, an inconsistent
>image is better than no image, but ideally you'd want to get a clean one.

Or, since this is a device mapper device, you can create a snapshot, and
then
use "dd" from the MDS snapshot (which should be consistent).  That's what I
do for my MDS backups, and it has saved me a couple of times.

Cheers, Andreas

>On 04/09/2013 11:33 AM, Kumar, Amit wrote:
>> Hi Kit
>>
>> This is good to know. Do I still need to shutdown the lustre FS? And
>>Umount the devices?
>>
>> Thank you
>> Amit
>>
>> Sent from my iPhone
>>
>> On Apr 9, 2013, at 10:27 AM, "Kit Westneat"
>><kwestneat@ddn.com<mailto:kwestneat@ddn.com>> wrote:
>>
>> Hi Amit,
>>
>> If you are doing a disk to disk backup, and the size of the backup disk
>>is >= the main disk, I would just use dd and not worry about formatting
>>the disk beforehand. The dd will replicate the filesystem structure
>>exactly, so there's no need to mkfs. I would do something like 'dd
>>if=/dev/dm-0 of=/dev/dm-2 bs=1M'.
>>
>> - Kit
>>
>> On 04/09/2013 02:40 AM, Kumar, Amit wrote:
>> I forgot to paste the link I referenced to perform backup: here it is:
>>http://wiki.lustre.org/manual/LustreManual18_HTML/BackupAndRestore.html
>> Any thoughts on this will be very helpful!
>> Thank you,
>> Amit
>>
>> From:
>>hpdd-discuss-bounces@lists.01.org<mailto:hpdd-discuss-bounces@lists.01.or
>>g> [mailto:hpdd-discuss-bounces@lists.01.org] On Behalf Of Kumar, Amit
>> Sent: Monday, April 08, 2013 12:47 PM
>> To: HPDD-discuss@lists.01.org<mailto:HPDD-discuss@lists.01.org>
>>(HPDD-discuss@ml01.01.org<mailto:HPDD-discuss@ml01.01.org>)
>> Subject: [HPDD-discuss] Lustre Disk to Disk MDS Backup Question
>>
>> Dear All,
>>
>> ³Version 1.8²
>>
>> We have both MGS & MDT mounted on two different block devices.
>> Now I would like to perform a disk to disk backup of both of these
>>block devices to another set of block devices.
>>
>> Although this link tells me how to perform that. There are some missing
>>things that I want to understand before I can perform this backup
>>
>> We have two devices /dev/dm-1 & /dev/dm-0 mounted as /mgs and /mdt
>>respectively.
>>
>> Now I have two more devices /dev/dm-2 & /dev/dm-3 which I want to mount
>>it as /mgs-backup and /mdt-backup and then perform the disk to disk
>>backup. Because we are not backing up any of the metadata right now.
>>
>> Here is where I get lost: when I want to make the lustre file system it
>>asked me if the device is going to be an mgs or mdt or it will be
>>combined. Now that I already have an /mgs and /mdt partition on this
>>node what will happen if I make new block device to be an mgs and mdt
>>partition, will this conflict with the existing ??????
>> Or can I just make the new devices just an ext3 partition and still be
>>able to make a disk to disk copy of meta data that I can restore when
>>needed.
>>

Cheers, Andreas
--
Andreas Dilger

Lustre Software Architect
Intel High Performance Data Division

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