[Lustre-discuss] Replacing faulty OSS/OST

Andrus, Brian Contractor bdandrus at nps.edu
Mon Oct 27 11:00:01 PDT 2014

As an add, I just went through this and had grief about magic numbers until I also used the --replace option to mkfs.lustre

Brian Andrus
ITACS/Research Computing
Naval Postgraduate School
Monterey, California
voice: 831-656-6238

> -----Original Message-----
> From: lustre-discuss-bounces at lists.lustre.org [mailto:lustre-discuss-
> bounces at lists.lustre.org] On Behalf Of Dilger, Andreas
> Sent: Tuesday, October 21, 2014 1:17 AM
> To: Jon Tegner
> Cc: hpdd-discuss at lists.01.org; Lustre discussion
> Subject: Re: [Lustre-discuss] Replacing faulty OSS/OST
> On 2014/10/21, 1:44 AM, "Jon Tegner" <tegner at foi.se> wrote:
> >Hi again,
> >
> >We are running lustre 2.5.3 on a small system, consisting of one
> >combined MGS/MDT and four combined OSS/OSTs. One of the OSS/OSTs
> has
> >faulty hardware, and need to be replaced. The procedure I plan on using
> >is the following.
> >
> >1. Deactivate the faulty OSS.
> >2. Make a file-level backup of it (not much data on it).
> >3. Temporarily deactivate it.
> >
> >The manual seems clear on how to perform these steps, what I'm a bit
> >uncertain about is how I introduce the replacement machine (which will
> >be a complete new one). Are there certain steps I need to take into
> >account, e.g., can will it be possible to create the new OST file
> >system with the old ost_index?
> >
> >4. Once the replacement is up, and its OST activated, the backup should
> >be restored. In the manual it is stated that e2label should be used to
> >set the file system label (based on the old ost_index in hex as I
> >understand it - a bit curious on this point, since I thought that would
> >be taken care of "automatically" (I have never done this when creating
> >OSTs before).
> If you reformat the new OST using:
>   mkfs.lustre --ost --index=N {other opts} /dev/XXX
> with the same index as is being replaced, then restore the OST backup into
> this filesystem, Lustre shouldn't care about the difference.  With new OST
> filesystems, you should also backup and restore the xattrs on all the files as
> is needed for the MDT filesystem backup/restore process.
> Cheers, Andreas
> --
> Andreas Dilger
> Lustre Software Architect
> Intel High Performance Data Division
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