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Disk certifies after 3 failed attemps

Active Member Customer


Have an external disk, Lacie Mini Rugged Thunderbolt, original HDD inside (normally use enclosure for SSD). Pretty sure I certified in SR when purchased a couple years ago. Used as bootable OS backup for old MBP laptop. Planned to re-purpose, so decided to re-certify.


Certify1: Failed early (within an hour), hung while writing, Error 66. Direct connect to iMac main TB2 port (as used by my OWC Thunderbay SR Raid 5 array normally).


Then did a successful 2 pass "Secure Erase" on disk utility on laptop, old MBP.


Certify2: Failed early, same error, different offset. But occurred exact moment I downloaded a new mac OS installer which auto-launched and started all my drives buzzing (I wasn't updating, just downloaded it). Disk was daisy chained off my 2 Thunderbays on iMac.


Certify 3: Failed early, same error, different offset again. Daisy chained off my 2 Thunderbays on iMac.


Certify 4: Successful, direct connected to laptop (not iMac). 2 passes.


Curious what the failures could mean if it later certified successfully? Think the Lacie enclosure, with integrated cable, is Thunderbolt 1. Laptop is TB 1. iMac is TB 2.


Could it be an issue with the iMac TB port? It's the same one I use for my 2 OWC Thunderbay4's running a 6 disk raid5 every day. Is there any way to test it?


I've read comments from Softraid Support on here that a disk "should never fail certify" and it means something wrong with the "system".


Also, is it generally a good idea to re-certify disks if planning to re-purpose them?


Thanks for your help. Cheers,




Topic starter Posted : 18/04/2021 5:04 pm
Member Admin

It is true a disk should never fail a certify. Either the disk is bad, or a component is bad. All a certify really does is write a complex pattern to the disk ,then read it back and verify the data is accurate. Should be 100% reliable. The SoftRAID driver is not used in a certify. It is just the macos x tools.


You can read in the log if these were read errors or write errors. Read verify errors are particularly bad, as that means what you write is not accurately being written.

Write errors could mean bad cable, bad disk, bad enclosure, disks connection is unreliable, etc. BUt write errors are "blind", so in general you should always be able to write to a disk.


I would be very careful with that disk. I assume it does not have any reallocated sectors?

BTW: Secure erase does not test the drive at all, it just writes a repeating pattern to the disk and there is no attempt to verify the data.

Posted : 18/04/2021 8:51 pm