add'l ideas to cure slow Time Machine backup
Over the past 10 days, the average duration of my Time Machine backups has gone from 1 minute to :42-:45 minutes. There's been no significant shift in my computing behavior during that time. To fix, I've tried nearly everything recommended in Pondini's terrific site -- can you see something that I've overlooked?
* iMac8,1 4GB, running OS X 10.6.8
* TM drive: Seagate GoFlex 1TB, 30 days old, was freshly formatted and 100% dedicated to TM; have tested both Firewire and USB; 356GB used
* Fusion virtual machines excluded from TM via Preferences
* no virus program running
Review of backupd items in system.log shows, after the first few weeks of speedy TM backups, a gradual decay -- can't pinpoint a cliff (that could be blamed on an installation, etc.) And there's no other TM-related messages ("deep traversal," etc) in the log. When I watch Activity Monitor during a TM cycle, I see low CPU usage by TM, and slow read/write speeds for disk activity.
Yes, I have:
* repaired permissions (frequently)
* done disk verify and repair on both internal and TM drives (nothing found)
* set drives to "no sleep"
* disabled Spotlight
* relaunched Finder (and, of course, rebooted the whole system)
* tested in Safe Mode (no improvement)
* run daily/weekly/monthly maintenance scripts and purged caches, using Cocktail (Ironically, it got dramatically worse yesterday after I did this!)
No, I have not yet reformatted the TM drive, nor reinstalled 10.6.8. Am I forgetting something else?
thx
iMac, Mac OS X (10.6.8)