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Extremely slow b/u to large saveset

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My system is a 1.6GHz with 256Mb memory, WinXP. I'm using a USB 2.0 external hard disk as my backup target with a 440Mbps transfer rate. Starting out with Retrospect, I decided to back up all of my local drive partitions to a single saveset on the USB drive (NTFS formatted). This took a couple of hours and created a saveset of 18Gb (gigabytes).




When I started an "incremental" backup to this same saveset last night, the performance was incredibly slow. After scanning the local drive Retrospect went into the "Preparing for backup" phase that took over an hour before it started to actually back up any files! Looking at the external disk with Explorer, what it seems to have been doing was to create a temporary catalog file (?) with a name of the form "Saveset.rfb.rfc". This file was 60Mb in size and it was probably populating it during this time (at least that's my guess). The external drive was fully busy during this time.




When it finally got around to backing up the changed files, it again would back up a few and then not show any progress for long periods of time. The activity light on the external disk was on constantly during all of this, so obviously it was doing something. I went away to do some other things and when I returned it had actually completed the backup successfully, but the log showed that it took 2 hours and 25 minutes to back up less than 2000 changed files! It didn't take much longer than that to do the initial full backup of 10's of thousands of files.




My conclusion is that Retrospect was working as designed, but that its method of operation simply does not scale well for trying to manage multi-gigabytes of files in a single large saveset. Maybe it's not optimized that well for storing to files since they assumed that nobody would back this much up to a file?




Anyway, what I may do is to do my backups one logical partition at a time, with each partition having its own saveset. This will be slightly less convenient operationally, but since each saveset will be smaller, the performance might be acceptable. I'll have to make sure to try this before my trial period expires, since I don' t think it's acceptable to have the software thrashing on the external drive for hours at a time when doing simple incremental backups.




Doug Gordon

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