[Lustre-discuss] 1.8.1 test setup achieved, what about maximum mdt size

[Piotr Wadas]

Hello, 
Proudly report working 

server & patched-client 1.8.1 + 2.6.27.23 + drbd 8.3.4 on 
Debian GNU/Linux (x86) sid/experimental

Test install made with two vmware-based virtual machines, and
base system (also debian gnu linux) as lustre patched client.

Note the following:

* First I tried with really small partitions, just a few MB,
and this was impossible to mkfs.lustre, because "file system too small for 
a journal", quite reasonably, though.

* Test install on virtualbox did not succeed because host-only network
bugs/limitation on virtualbox

* Confirmed one can use LVM's PVs or LVs as lustre block devices.

* Confirmed working with MGS/MDT/OSTs (actually two OSTs for now) AND 
client on very same (fully-virtual) machine, for testing purposes, no 
problems with that so far.

Now, I did a simple count of MDT size as described in lustre 1.8.1 manual,
and setup mdt as recommended. The question is, no matter I did right count
or not, what actually will happen, if MDT partition runs out of space?
Any chances to dump the whole MGS+MDT combined fs, supply a bigger block 
device, or extend partition size with some e2fsprogs/tune2fs trick ?
This assumes, that no matter how big MDT is, it will be exhausted someday.

One possible solution is simply to add/create another FS, with another 
MGS/MDT. But the question persists :) 

And one more thing - I use combined MGS/MDT. What's actually about MGS 
size? I mean, if I use separate MGS and MDT, what size it should have,
and how management service works, regarding to its block-device storage ?

Regards,
Piotr Wadas