Sam Skipsey wrote:
> On 24 May 2011 15:17, Wahid Bhimji <[log in to unmask]> wrote:
>> dpm-drain takes an --size option that will drain a limited amount and spread it around all other filesystems :
>> - it should evenly spread it across other filesystems (usual round robin)
>> - obv. you may want to mark the other smaller filesystems READONLY to avoid them getting any of the files.
>>
>
> Although, if a filesystem fills up, DPM will stop using it, so for the
> first drained filesystem this is unnecessary. (I'd RDONLY the fuller
> filesystems now in any case, to stop them getting worse before you
> drain them).
>
>> Sam has (I believe) a tool that may do something cleverer but I've not seen it - but if he is willing to inflict it on others and you are willing to try it (and it does something good) then we can add it to the toolkit.
>>
>
> I've not touched that tool in a while, and really don't want to
> inflict it on others (in any case, it is no more efficient than
> marking things RDONLY, without some kind of targeted replication
> functionality being available on the DPM you have installed).
This algorithm has wider applicability. Even if you aren't happy with
the implementation, I'd be interested in the algorithm you use.
Whilst Lustre has a more intelligent algorithm for disks that are nearly
full, there's still merit in rebalancing files when you add new servers.
>
>> BTW: The modifications to DPM that allow weighting of filesystems seems almost ready- but the official version that will be in will be an EMI one so probably not immediately useful to you. We could prod for a preview.
Just for interest, the algorithm that Lustre uses is:
http://wiki.lustre.org/manual/LustreManual20_HTML/ManagingStripingFreeSpace.html#50438209_pgfId-1294034
>>
>
> I think we should. Everyone suffers from this issue.
Chris
>
> Sam
>
>> Wahid
>>
>> On 24 May 2011, at 15:06, Alessandra Forti wrote:
>>
>>> Hi,
>>>
>>> the 4 smaller file systems are now almost full and I'd like to know what is the best procedure, if there is one, to transfer data to other bigger and emptier file systems.
>>>
>>> cheers
>>> alessandra
>>>
>>
>> --
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>> Scotland, with registration number SC005336.
>>
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