1. The global bitmap in ocfs2 maps all the clusters on the disk. That
includes,
the space used by the super block, root dir, system dir, system files, etc.
Hence the usage on a clean fs. Most of this space is being used by the
journals.
# echo "stat //journal:0000" | debugfs.ocfs2 -n /dev/sdX
2. ocfs2 does not preallocate space for inodes. It allocates space on
demand.
You can view the space allocated to inodes for slot 0 as follows:
# echo "stat //inode_alloc:0000" | debugfs.ocfs2 -n /dev/sdX
3. du does not reflect space used by filesystem metadata.
Robinson Maureira Castillo wrote:
Hi all,
I'm testing OCFS2 as a cluster filesystem for a mail system based on maildir,
so basically the filesystem must be able to deal with lots of directories, and
lots of small files.
The first "oddity", is that when I mount a newly formated ocfs2 fs, it already
contains used space:
[EMAIL PROTECTED] /]# df /cgp02
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb2 10710016 135004 10575012 2% /cgp02
The info for that partition:
[EMAIL PROTECTED] /]# fsck.ocfs2 -n /dev/sdb2
Checking OCFS2 filesystem in /dev/sdb2:
label: cgp02
uuid: ad 2e 20 38 60 70 45 b8 97 68 48 d7 b9 88 5e 59
number of blocks: 10710016
bytes per block: 1024
number of clusters: 2677504
bytes per cluster: 4096
max slots: 2
After creating 300 directories, and 300 files (2kB each) on each directory,
renaming them, and then deleting, the df output is:
[EMAIL PROTECTED] cgp02]# df /cgp02/
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb2 10710016 228256 10481760 3% /cgp02
I've created another partition, using these parameters:
[EMAIL PROTECTED] cgp01]# fsck.ocfs2 -n /dev/sdb1
Checking OCFS2 filesystem in /dev/sdb1:
label: cgp01
uuid: cf 1c 34 6b 10 87 45 37 84 fd 98 ea 8a 46 d2 7a
number of blocks: 2441724
bytes per block: 4096
number of clusters: 2441724
bytes per cluster: 4096
max slots: 2
After creating 100000 accounts, and deleting them, the df output is:
[EMAIL PROTECTED] cgp01]# df /cgp01
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb1 9766896 2122080 7644816 22% /cgp01
The usage reported by du in that directory:
[EMAIL PROTECTED] cgp01]# du -sh .
23K .
If I create the 100000 accounts again...
[EMAIL PROTECTED] example.lan]# df /cgp01/
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb1 9766896 3342204 6424692 35% /cgp01
[EMAIL PROTECTED] example.lan]# du -sh .
531M .
After a reboot...
[EMAIL PROTECTED] ~]# df /cgp01/
Filesystem 1K-blocks Used Available Use% Mounted on
/dev/sdb1 9766896 3344956 6421940 35% /cgp01
The application is using a 2-level hashing for directory creation, a typical
user account resides on a hierarchy structure as shown below, and with those
default files:
[EMAIL PROTECTED] example.lan]# ll aa.sub/g.sub/test10110.macnt/
total 1
-rw-rw---- 1 root mail 134 Aug 2 16:57 account.info
-rw-rw---- 1 root mail 78 Aug 2 16:57 account.settings
-rw-rw---- 1 root mail 0 Aug 2 16:57 INBOX.mbox
Where are the other 2.8GB of data being used? Is this an expected behaviour? If
so, then maybe I'm doing something terribly wrong, and I would appreciate an
advise on what settings should I use for this scenario.
On production systems, the size of the LUN presented is 1TB, 3 LUN per server,
holding ~300000 user accounts, and expecting 1 million in a near future.
Thanks in advance, and best regards,
__________________________
Robinson Maureira Castillo
Soluciones Integrales S.A.
Eleodoro Flores 2425, Ñuñoa, Santiago - Chile
Central: (56 2) 411 9000 Fax: (56 2) 411 9001
Directo: (56 2) 411 9047
Móvil: (56 9) 599 4987
e-mail: [EMAIL PROTECTED]
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