Performance problems with millions of inodes

Christoph Litauer
2008-06-25T14:42:39Z

Hi,

sorry if this has been asked before, I am new to this mailing list. I
didn't find any hints in the FAQ or by googling ...

I have a backup server driving two kinds of backup software: bacula and
backuppc. bacula saves it's backups on raid1, backuppc on raid2
(different hardware, but both fast hardware raids).
I have massive performance problems with backuppc which I tracked down
to performance problems of the filesystem on raid2 (I think so). The
main difference between the two backup systems is that backuppc uses
millions of inodes for it's backup (in fact it duplicates the directory
structure of the backup client).

raid1 consists of 91675 inodes, raid2 of 143646439. The filesystems were
created without any options. raid1 is about 7 TB, raid2 about 10TB. Both
filesystems are mounted with options
'(rw,noatime,nodiratime,ihashsize=65536)'.

I used bonnie++ to benchmark both filesystems. Here are the results of
'bonnie++ -u root -f -n 10:0:0:1000':

raid1:
-------------------
Sequential Output: 82505 K/sec
Sequential Input : 102192 K/sec
Sequential file creation: 7184/sec
Random file creation : 17277/sec

raid2:
-------------------
Sequential Output: 124802 K/sec
Sequential Input : 109158 K/sec
Sequential file creation: 123/sec
Random file creation : 138/sec

As you can see, raid2's throughput is higher than raid1's. But the file
creation times are rather slow ...

Maybe the 143 million inodes cause this effect? Any idea how to avoid it?