On 4/8/2010 12:23 PM, Les Mikesell wrote:
> On 4/8/2010 9:48 AM, Norbert Schulze wrote:
>   
>>> Raid5?  That has horrible write performance,
>>>       
>> It is a RAID50
>>
>> IMHO: BackupPC_nightly mainly reads from disk!?
>>     
> It traverses the pool directory, stat()'ing each inode (which isn't like 
> to be near the directory) looking for entries that only have one link, 
> meaning that all of the pc backups that previously linked to it have 
> expired, and deletes these files.  The deletes involve small writes back 
> to the directory, inode, and free space list which will be slow as the 
> raid5 must do a read before the write and then update the parity, 
> essentially tying the speed to the slowest disk.  How many of these you 
> do will relate to the turnover of files on the targets.  If you do a 
> large number of maildir type folders with a lot of activity there could 
> be a lot.
>
>   

A few comments.

1) Raid5X is going to kill your performance. As mentioned in a previous
message, convert to RAID10 if you can afford the space decrease.

2) Make sure you are setting the 'noatime' option on your backuppc pool
storage partition

3) Edit your updatedb.conf and add the path to your backuppc pool to
PRUNEPATHS. updatedb usually runs nightly on most systems around 4am as
a cron job and allowing it to index your backuppc pool will take quite a
while if many files are changing nightly.

4) Look at this page for tips on speeding up your backup.
http://sourceforge.net/apps/mediawiki/backuppc/index.php?title=Speedupbackups

Also, are you using a BBU on your Adaptec 3805 card? Adaptec's page
indicates the controller does support a BBU. If you are, as a previous
person mentioned, make sure you have write-caching enabled on the card.

-- 
         Ryan Manikowski


]] Devision Media Services LLC [[
         www.devision.us
 ryan AT devision DOT us | 716.771.2282


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