[Lustre-discuss] specifying OST

[Mag Gam]

Thank you. This makes very good sense. (you should wiki this :-)


A similar question, is it possible to move from a striped volume to a
non-striped volumes because I want to decommission an OST. For
instance,

lctl dl
 0 UP mgc MGC10.143.245.201 at tcp a5f811be-0c46-09ee-2b5d-f59c569dba2e 5
 1 UP lov ddn_home-clilov-00000102280ca800
d4470bbd-9917-1651-13d0-7736bfcac109 4
 2 UP mdc ddn_home-MDT0000-mdc-00000102280ca800
d4470bbd-9917-1651-13d0-7736bfcac109 5
 3 UP osc ddn_home-OST0000-osc-00000102280ca800
d4470bbd-9917-1651-13d0-7736bfcac109 5
 4 UP osc ddn_home-OST0001-osc-00000102280ca800
d4470bbd-9917-1651-13d0-7736bfcac109 5
 5 UP osc ddn_home-OST0002-osc-00000102280ca800
d4470bbd-9917-1651-13d0-7736bfcac109 5
 6 UP osc ddn_home-OST0003-osc-00000102280ca800
d4470bbd-9917-1651-13d0-7736bfcac109 5


I want to decommission 5 (ddn_home-OST0002-osc-00000102280ca800), and
I have a striped and non-striped data. The goal is I don't want to
disturb the clients. I have the option to disable writes but not
reads.

Any ideas how I can do that?


TIA


On Wed, Jul 16, 2008 at 6:38 AM, Wojciech Turek <wjt27 at cam.ac.uk> wrote:
> Hi,
>
> Type  'lfs help setstripe' on lustre client node
>
>>lfs help setstripe
> setstripe: Create a new file with a specific striping pattern or
> set the default striping pattern on an existing directory or
> delete the default striping pattern from an existing directory
> usage: setstripe <filename|dirname> <stripe_size> <stripe_index>
> <stripe_count>
>      or
>      setstripe <filename|dirname> [--size|-s stripe_size]
>                                   [--index|-i stripe_index]
>                                   [--count|-c stripe_count]
>      or
>      setstripe -d <dirname>   (to delete default striping)
>       stripe_size:  Number of bytes on each OST (0 filesystem default)
>                     Can be specified with k, m or g (in KB, MB and GB
> respectively)
>       stripe_index: OST index of first stripe (-1 filesystem default)
>       stripe_count: Number of OSTs to stripe over (0 default, -1 all)
>
> Ok lets now using information above set that a particular file will be
> written to a particular OST.
> For this exercise we assume we have a file system that consists of four OST
>
> lctl dl
>  0 UP mgc MGC10.143.245.201 at tcp a5f811be-0c46-09ee-2b5d-f59c569dba2e 5
>  1 UP lov ddn_home-clilov-00000102280ca800
> d4470bbd-9917-1651-13d0-7736bfcac109 4
>  2 UP mdc ddn_home-MDT0000-mdc-00000102280ca800
> d4470bbd-9917-1651-13d0-7736bfcac109 5
>  3 UP osc ddn_home-OST0000-osc-00000102280ca800
> d4470bbd-9917-1651-13d0-7736bfcac109 5
>  4 UP osc ddn_home-OST0001-osc-00000102280ca800
> d4470bbd-9917-1651-13d0-7736bfcac109 5
>  5 UP osc ddn_home-OST0002-osc-00000102280ca800
> d4470bbd-9917-1651-13d0-7736bfcac109 5
>  6 UP osc ddn_home-OST0003-osc-00000102280ca800
> d4470bbd-9917-1651-13d0-7736bfcac109 5
>
> Lets say we would like to create file my_work.dat on ddn_home-OST0002
> The command line for that will look like this:
>> lfs setstripe -i 3 -c 1 /home/my_home/my_work.dat
>
> Now if you create file my_work.dat in /home/my_home it will be created on
> ddn_home-OST0002.
>
> If you would like to make sure that new file is on the OST of you choice use
> 'lfs getstripe' command  to checkout striping pattern on the file you've
> just created.
>> lfs getstripe /home/my_home/my_work.dat
>
> I know that manual doesn't give you an exact example how to do that but it
> gives an idea how striping works so please experiment with it to fond out
> what else you could do with lfs setstripe.
>
> I hope it helps.
>
> Cheers
>
> Wojciech
>
>
> Mag Gam wrote:
>>
>> BTW,
>>
>> I have read that manual page several times,
>>
>> http://manual.lustre.org/manual/LustreManual16_HTML/StripingAndIOOptions.html#50544707_pgfId-5529
>>
>> And I could still not find out how to do this...
>>
>>
>> TIA
>>
>>
>> On Tue, Jul 15, 2008 at 8:38 PM, Mag Gam <magawake at gmail.com> wrote:
>>
>>>
>>> Really? How ?
>>>
>>> I been trying to figure this out.
>>>
>>> Can you please give me an example?
>>>
>>> TIA
>>>
>>> On Mon, Jul 14, 2008 at 7:16 AM, Dhruv <DhruvDesaai at gmail.com> wrote:
>>>
>>>>
>>>> You can use the lfs utility to route your file to any particular OST/
>>>> s.
>>>>
>>>> On Jul 11, 4:38 pm, "Mag Gam" <magaw... at gmail.com> wrote:
>>>>
>>>>>
>>>>> is it possible to create a file on a particular OST?
>>>>>
>>>>> TIA
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