Hello, On 3/30/2006 9:38 AM, Christoph Litauer wrote:
Hi,I just searched the archives but didn't find hints. Sorry if this question has been asked before. I am using bacula-1.36.3 for the backup of about 12 linux clients. At the moment I just use an external hardware raid as (File-)backup device: Device { Name = FileStorage Media Type = File Archive Device = /storage LabelMedia = yes; Random Access = Yes; AutomaticMount = yes; RemovableMedia = no; AlwaysOpen = no; Maximum Volume Size = 2147483648 # 2GB } The backups are done in parallel with a maximum of 20 concurrent jobs. The most recent backup of one of the clients (about 1,6 GB of data) consists of a full, 1 differential and 2 incrememtal backups, located on 16 backup files (FileStorage). Running the restore I get a "Rate" of about 500 KB/sec (restoring to a local filesystem on the storage server). The raid device is able to deliver 12MB/sec. The local filesystem is able to write about 10MB/sec, My conclusion for that degraded performance is that even if I use FileStorage as a random access media, the restore process recovers the data by sequentially reading all the 16 backup files "searching for the right files". I would have expected a rate of nearly native disk speed because the backup files could be "seeked".
As far as I know, there are some problems using seeking instead of reading and interpreting which lead to Kern disabling volume seeking for file volumes, so your conclusion is right.
A solution would be to not perform concurrent backups. But then the backup window gets significantly wider (especially for the incrementals). Any solutions, hints? Would my problem disappear if I upgrade to 1.38.x?
Perhaps, I don't know if that peculiar problem is resolved by now. You might read through the release notes of the 1.38 versions.
Possible solution, assuming you've got enough disk space: Use spooling. It's - theoretically - nonsense doing this with file volumes, but might reslove the performance problems you see. Try to put the spool space onto different physical disks and a different filesystem than the real storage space!
Arno
Thanks a lot in advance. If you need more of my configuration files, no problem, please tell me.
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