Intermittent fantastically slow backup (PST)

[aandi]

Retrospect 7.6.123 on XP backing up an XP client to FILE. One backup task runs nightly to backup about 4 GB of PST files (from Outlook: no Exchange Server anywhere).

 

Sometimes this runs at around 200+ MB/minute. This is consistent with the other clients around the place. But more often it runs closer to 10-20 MB/min.

 

Stopping the backup and retrying sometimes gets the backup at the faster speed. Sometimes rebooting server or client seems to help, sometimes not. There is not a variation of speeds between these two extremes: it is either very fast or very slow. Outlook is NOT running.

 

I speculate that something can cause the backup client to switch into a slower mode (locking?). I believe I have seen the backup start fast and switch to slow, but never go back to fast from slow.

 

The client is not cluttered with extra software. It has XPSP3 and Office 2007 out of the box, and Retrospect Client is the only add on.

 

This effect was seen on the PC which preceded this one, but is not seen on other similar PCs with large PST file sets.

 

This has been going on for years, but the size of the PST files now means that it is typically overrunning into the working day.

 

Thanks in advance.