[Ocfs2-users] Space used on file system although empty.

[Guy]

Hi,

I'm busy doing a bit of testing with an ocfs2 partition on an iSCSI target.
I'm using Ubuntu 9.10 (Karmic) with the latest kernel module and tools
included with that release (tools version 1.4.2 I believe). And I made the
fs with the following command:

mkfs.ocfs2 -L mailstore1 -N 4 -T mail /dev/sdb1

Initially the fs showed 1.2G of 20G already used. Creating files with dd and
deleting them again puts the space usage back down normally. I ran bonnie++
1.96 (threaded version) overnight and now it shows 3.1G used when the only
thing on the fs is the lost+found directory.
I ran fsck.ocfs2 on the partition but it found no errors or orphaned inodes
as was happening before upgrading Ubuntu.

Is this extra space usage after a lot of writing/deleting expected?
If so, can I calculate how much space I'm like to have to sacrifice to this
(the 20GB is for testing, the final iSCSI target would likely be about
1.5TB)? The iSCSI target is on a SAN provided by our hosting company, so it
would help if we can have a more accurate prediction of the space we're
doing to need to buy.

Also, are there any other options I can use when creating the fs that might
be better for usage as a mail store?
We hit about 700 concurrent dovecot connections at peak. We use Maildir++
and most messages are probably between 10KB and 200KB, with some being up to
20MB with attachments etc.

Any other advice/experiences related to this sort of usage would also be
appreciated.

Thanks
Guy

-- 
Don't just do something...sit there!
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