Lustre discuss - May 2006 - Questions about reiserfs and meta date requirements

On Mon, 2004-04-26 at 03:51, David S. wrote:
> 
> where the devices "/dev/sda1" and "/dev/sdb1" are in
the SAN.  However,
> I haven''t been able to make the above example work with
"--fstype ext3"
> replaced by "--fstype reiserfs".  In that latter case, the
"lconf" command
> prints the message
> 
> 	OSD: ost1 ost1_UUID obdfilter /dev/sdb1 0 reiserfs no 0 0
> 
> and then hangs - no Lustre file system is mounted at
"/mnt/lustre".
> 
> So is it the case that Lustre won''t work with a reiserfs
"back-end", or
> am I doing something wrong?
That is correct, ext3 is the only supported file system backend.  Given
the vast improvements to ext3 over the last few years, we have not found
any need, or any customer demand, to support other file systems.
> if I have X gigabytes
> of data served from my OSTs, how much space should I commit to the meta-
> data server supporting them?  I''d be gratetul for any guidance.
It depends on your own metadata requirements, and is completely
unrelated to the amount of OST storage.

We use 1% of the disk for the ext3 journal (up to a maximum of 400MB). 
If you add to that ~4k for each file that you plan to create, that
should be plenty (ie, for 10 million files, you should create an MDS of
at least 40.4 GB).

Thanks--

-Phil

I''m configuring Lustre 1,0.4 on a dual Zeon 2.4.24 system, patched with
with the "vanilla" 2.4.24 patch series from the Lustre distribution,
and
a fibre channel storage array - I can provide more details on the system 
and hardware configuration if they''re relevant.  Following the example
in the Lustre "How-To", section 1.4.2 "Using Supplied
Configuration
Tools", I''ve been able to get Lustre working with the client, MDS,
and
OST on a single node with the commands:

	lmc -o local.xml --add node --node localhost
	lmc -m local.xml --add net --node localhost --nid localhost --nettype tcp
	mc -m local.xml --add mds --node localhost --mds mds1 --fstype ext3 --dev
/dev/sda1
	lmc -m local.xml --add ost --node localhost --ost ost1 --fstype ext3 --dev
/dev/sdb1
	lmc -m local.xml --add mtpt --node localhost --path /mnt/lustre --mds mds1
--ost ost1
	lconf --reformat --gdb local.xml 

where the devices "/dev/sda1" and "/dev/sdb1" are in the
SAN.  However,
I haven''t been able to make the above example work with "--fstype
ext3"
replaced by "--fstype reiserfs".  In that latter case, the
"lconf" command
prints the message

	OSD: ost1 ost1_UUID obdfilter /dev/sdb1 0 reiserfs no 0 0

and then hangs - no Lustre file system is mounted at "/mnt/lustre".

So is it the case that Lustre won''t work with a reiserfs
"back-end", or
am I doing something wrong?

My other question concerns meta data requirements: if I have X gigabytes
of data served from my OSTs, how much space should I commit to the meta-
data server supporting them?  I''d be gratetul for any guidance.

Thanks in advance,

David S.
dgs@gs.washington.edu