Slow Verify

I run a weekly verify to ensure that the archive is stable. (I also flatten the archive weekly).

This operation is now taking 9 hours for an archive that is about 126G (on a 150G disk partition mounted on an Airport Extreme). How long should this operation take?

Glenn Henshaw wrote:I run a weekly verify to ensure that the archive is stable. (I also flatten the archive weekly).

I approve.

This operation is now taking 9 hours for an archive that is about 126G (on a 150G disk partition mounted on an Airport Extreme). How long should this operation take?

The bulk of the verify action is consumed with reading every byte of the archive and checking its integrity. Most of the archive is read just once, but it is read from start to finish.

Doing the math:

126,000 (126GB in megabytes) / 9 (hours) / 60 (minutes) / 60 (seconds) = 3.89 MB/sec transfer rate

That sounds like an 802.11n wireless network running at close to its maximum capacity. If you're verifying the volume via a wireless network connection, then that's just about right.

- A verify over a 100Mb ethernet LAN would take about 3-4 hours.

If you have another computer on your network that's connected via ethernet, schedule it to preform the weekly verify. It doesn't matter what computer does the verify; that computer doesn't even need an identity key.

- An external drive connected via Firewire 800 should take about 30 minutes.

If you need to perform a fast verify, disconnect the drive from the Airport basestation, connect it to any computer with QRecall installed, verify the archive, then put it back.

Thanks for the explanation and tip. I have another ethernet based machine that I'll set up to do the verify.