Last week I replaced the 512GB 7200rpm HDD in my Mid-2010 MacBook Pro with a 512GB SSD (Crucial 550). The performance improvement in most areas is welcome, but one thing is now considerably slower: my weekly SuperDuper clone.

Prior to the upgrade, doing a smart copy of the MBP's disk (where only the files that have changed are copied) to a portable USB HDD would usually take around one hour. Since the SSD upgrade, doing a smart copy to the same HDD now takes nearer 3 hours.

I dare say there's a logical explanation for this... but what is it, and is there anything I can do about it?

EDIT: Actually, it's worse than I thought... both the backups I've done since the upgrade have taken 10 HOURS EACH. The first one I assumed was something to do with the drive ID changing, even though most of the files hadn't changed. I wrote this post about 2 hours into my second backup when it looked like it was mostly done, but still had to leave it running overnight, and when I got up this morning I saw that it had again taken 10 hours.

The backup drive is a portable Toshiba 1TB, with three partitions (one for each of my Macs), which connects to my MBP via USB 2.0. I've backed up my other two non-SSD Macs to it in the meantime and they didn't take any longer than usual, so there's nothing physically wrong with the drive, though that doesn't rule out an issue with one partition I guess.

  • A couple of questions: How many times have you found the performance to be slow, considering you only replaced the drive last week? What are you writing to? I expect performance is more likely constrained by write performance rather than read performance. – Mike Meyers May 8 '14 at 4:19
  • I've updated the question with this information. – calum_b May 8 '14 at 10:03
  • Hmmm. Sounds a bit bizarre. Is there anything in the log that tell you anything useful (from Window menu/Show Log). – Mike Meyers May 9 '14 at 0:03
  • Nothing at all, looks normal apart from the length of time it takes! Have since contacted ShirtPocket support and they're mystified too. I did randomly try turning TRIM support off last night and managed to do a backup in 40 minutes, so maybe that's the secret (Crucial say it's not required on their drives), but on the other hand it did only have 24 hours worth of data to backup rather than a week's worth at that point. We'll see... – calum_b May 9 '14 at 10:35
  • are these incremental backups? Or straight, fresh backups every time? If the former, that explains it. – DrZ214 Dec 31 '15 at 10:25

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