[Lustre-discuss] questions about an OST content
Andreas Dilger
andreas.dilger at oracle.com
Mon Nov 8 12:04:57 PST 2010
On 2010-11-08, at 11:39, Bob Ball wrote:
> Don't know if I sent to the whole list. One of those days.
>
> remade the raid device, remade the lustre fs on it, but the disks won't mount. Error is below. How do I overcome this?
>
> mounting device /dev/sdc at /mnt/ost12, flags=0 options=device=/dev/sdc
> mount.lustre: mount /dev/sdc at /mnt/ost12 failed: Address already in use retries left: 0
> mount.lustre: mount /dev/sdc at /mnt/ost12 failed: Address already in use
> The target service's index is already in use. (/dev/sdc)
Looks like you didn't copy the old "CONFIGS/mountdata" file over the new one. You can also use "--writeconf" (described in the manual and several times on the list) to have the MGS re-generate the configuration, which should fix this as well.
> On 11/8/2010 5:01 AM, Andreas Dilger wrote:
>> On 2010-11-07, at 12:32, Bob Ball <ball at umich.edu> wrote:
>>> Tomorrow, we will redo all 8 OST on the first file server we are redoing. I am very nervous about this, as a lot is riding on us doing this correctly. For example, on a client now, if I umount one of the ost, without first taking some (unknown to me) action on the MDT, then the client will hang on the "df" command.
>>>
>>> So, while we are doing the reformat, is there any way to avoid this "hang" situation?
>>
>> If you issue "lctl --device %{OSC UUID} deactivate" on the MDS and clients then any operations on those OSTs will immediately fail with an IO error. If you are migrating I objects from those OSTs, I would have imagined you already did this on the MDS or new objects would have continued to be allocated there
>>
>>> Is the --index=XX argument to mkfs.lustre hex, or decimal? Seems from your comment below that this must be hex?
>>
>> Decimal, though it may also accept hex (I can't check right now).
>>
>>> Finally, does supplying the --index even matter if we restore the files below that you mention? That seems to be what you are saying.
>>
>> Well, you still need to set the filesystem label. This could be done with tune2fs, but you may as well specify the right index from the beginning.
>>
>>> On 11/6/2010 11:09 AM, Andreas Dilger wrote:
>>>> On 2010-11-06, at 8:24, Bob Ball<ball at umich.edu> wrote:
>>>>> I am emptying a set of OST so that I can reformat the underlying RAID-6
>>>>> more efficiently. Two questions:
>>>>> 1. Is there a quick way to tell if the OST is really empty? lfs_find
>>>>> takes many hours to run.
>>>> If you mount the OST as type ldiskfs and look in the O/0/d* directories (capital-O, zero) there should be a few hundred zero-length objects owned by root.
>>>>
>>>>> 2. When I reformat, I want it to retain the same ID so as to not make
>>>>> "holes" in the list. From the following information, am I correct to
>>>>> assume that the id is 24? If not, how do I determine the correct ID to
>>>>> use when we re-create the file system?
>>>> If you still have the existing OST, the easiest way to do this is to save the files last_rcvd, O/0/LAST_ID, and CONFIGS/*, and copy them into the reformatted OST.
>>>>
>>>>> /dev/sdj 3.5T 3.1T 222G 94% /mnt/ost51
>>>>> 10 UP obdfilter umt3-OST0018 umt3-OST0018_UUID 547
>>>>> umt3-OST0018_UUID 3.4T 3.0T 221.1G 88%
>>>>> /lustre/umt3[OST:24]
>>>>> 20 IN osc umt3-OST0018-osc umt3-mdtlov_UUID 5
>>>> The OST index is indeed 24 (18 hex). As for /dev/sdj, it is hard to know from the above info. If you run "e2label /dev/sdj" the filesystem label should match the OST name umt3-OST0018.
>>>>
>>>> Cheers, Andreas
>>>>
Cheers, Andreas
--
Andreas Dilger
Lustre Technical Lead
Oracle Corporation Canada Inc.
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