Hi,
There are mails coming in from various directions asking about
how to currently make use of many partitions of 1 or 2 TB
within LCG on an SE.
The current situation is this in that per ClassicSE you can only
have one disk partition per VO per SE.
There are few ways to consider to solve this, all of which have
problems and as a result leave you fairly stuck.
1) On the same host you can create a RAID5 with LCM or something
and put XFS on it. XFS gives you a maximum partition of at least
a PB though I'm not sure of the exact size.
However we are easily able to break and LVM system at RAL
with out to much difficulty. Also XFS in RH7.3 is best avoided.
2) Use some kind on SAN technology, eg GFS, iSCSI to give to huge
massive file system. Again you will need to use XFS on top.
3) Wait for dcache as a disk pool manager.
We are having a bit more success recently with this here and
I am feeling more confident about it.
We would hope to have a 8 TB (4 partitions of 2TB on 2 hosts) some
time next week. We've done it once now and hope to now be able to
deploy it again in a more automated way.
For those considering this option and wanting to plan for it I would
recommend that you will need a front end DCache HEAD node for your
storage. One of the GridPP provides boxes is just perfect. Putting
a mirrored pair or something on the head node may be a very good idea
since loosing the head node and the database on it results in the
loss of ALL of your data across systems.
We will provide some more information, pointers to documentation etc
if we have success next week.
4) Internal releases of the edg-se claim to be able to help but is not
an option for deployment today.
Steve
--
Steve Traylen
[log in to unmask]
http://www.gridpp.ac.uk/
|