On 3/22/07, John T. Yocum <[EMAIL PROTECTED]> wrote: > On our backup servers, they are all showing a very high wait during > backups. Here's a screenshot from one of them > http://www.publicmx.com/fh/backup2.jpg. At the time it was doing two > backups, and a nightly. > > Any advice on improving performance, would be much appreciated.
It's quite easy to see how the server is doing nothing except waiting for disk IO to complete. If it were waiting for the clients you would have idle time. If it were busy compressing data you would see high CPU utilization. Especially when nightlies are running you will see this as BackupPC scans the backup archive which results in a huge number of seeks. If you also run iostat you can confirm that you will see that "tps" is maxed out on you backup device while the block read/write rate remains low. The primary issue is the huge number of hardlinks BackupPC creates and these get scattered all over the disk because of the way your average file system lays them out on disk. I don't know of any file systems which perform significantly better than ext3. xfs, jfs and reiserfs all seem to suffer from the same issue under BackupPC load but I haven't done any back to back benchmarks myself. The best way is to throw disk spindles at it. RAID 10 works great as a 4-disk array has the potential to speed up random reads by 4x and random writes by 2x. While RAID 5 will tyically have decent random read performance, it usually has horrible random small write performance sometimes worse than a single drive! Having a battery backed raid controller here will help write performance immensely. -Dave ------------------------------------------------------------------------- Take Surveys. Earn Cash. Influence the Future of IT Join SourceForge.net's Techsay panel and you'll get the chance to share your opinions on IT & business topics through brief surveys-and earn cash http://www.techsay.com/default.php?page=join.php&p=sourceforge&CID=DEVDEV _______________________________________________ BackupPC-users mailing list [email protected] https://lists.sourceforge.net/lists/listinfo/backuppc-users http://backuppc.sourceforge.net/
