[Lustre-discuss] Failover Setup MDS/MDT

[Klaus Steden]

Hello Heiko,

If I'm not mistaken, 'MDS' refers to the metadata _server_, while 'MDT'
refers to the metadata _target_, i.e. the distinction is akin to that
between 'OSS' and 'OST'. The MDS is a server node; the MDT is the volume
where all the metadata for your volume is stored.

The handbook recommends an MDT size about 1-2% of the size of your total
volume size, i.e. if your total CFS volume is 10 TB, the MDT would be about
200 GB. This is fairly conservative, so you may want to err on the side of
growth by using a larger volume than that. If you can spare the disk, you're
certainly not sacrificing anything by over-provisioning your MDS.

hope this helps,
Klaus

On 6/25/08 5:29 AM, "Heiko Schroeter" <schroete at iup.physik.uni-bremen.de>did
etch on stone tablets:

> Am Mittwoch, 25. Juni 2008 14:19:11 schrieb Brian J. Murrell:
>> On Wed, 2008-06-25 at 07:36 +0200, Heiko Schroeter wrote:
>>> How can one determine the size for the MDT partition or is that the same
>>> as the MDS device ?
>>> (As far as i can see the MDT takes the DIR info etc. So it should be
>>> larger than the MDS.)
>> 
>> An MDT is the device (i.e. the disk) that Lustre in an MDS (the server)
>> uses to manage the metadata.  Maybe that clears it up?
> 
> Well yes ok, but what about the sizes of the partitions ?
> 
> The docs present an example calculating the inode space needed on an 'MDS'.
> (3.2.2 Calculating MDS Size)
> 
> That what actually confuses me a bit.
> 
> So when the MDS partitions holds the inodes of the lustre system what will be
> the partition size of the MDT device ?
> Or should it read 'MDT' partition size in the docs and the MDS partition size
> doesn't matter at all ?
> 
> Thanks and Regards
> Heiko
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