badblocks(8) with ZFS, with and without CoreStorage

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badblocks(8) with ZFS, with and without CoreStorage

Post by grahamperrin » Thu Oct 11, 2012 1:37 am

Please, can anyone think of precautions to using badblocks(8) (say, from an Ubuntu Live disc) with either of the following environments?

  1. with ZEVO ZFS without CoreStorage
  2. with ZEVO ZFS with CoreStorage
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Re: badblocks(8) with ZFS, with and without CoreStorage

Post by si-ghan-bi » Tue Oct 16, 2012 4:16 am

I'm interested in the topic. I decided to check for bad sectors my new drives, unfortunately I already formatted them with ZFS and a complete wipe is not possible.
- What is the best way to check bad blocks?
- Does the filling followed by the immediate deletion of the new file affect future fragmentation? Maybe due to the copy-on-write policy new files will be written immediately in old areas in the beginning of the disk, instead of the ones freed by these temporary files. Should I use a snapshot to take care of this?
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Re: badblocks(8) with ZFS, with and without CoreStorage

Post by grahamperrin » Tue Oct 16, 2012 2:00 pm

si-ghan-bi wrote:… fragmentation? … 


– deserves its own topic: hard disk optimisation for performance purposes.
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Re: badblocks(8) with ZFS, with and without CoreStorage

Post by grahamperrin » Tue Oct 16, 2012 2:41 pm

si-ghan-bi wrote:… What is the best way to check bad blocks?… 


I'd like to keep this topic focused on the badblocks approach alone.

There's a question in Ask Different: What free or open source software can I use with Mac hardware to verify integrity of every block of a disk where Core Storage is used?

My primary reason for asking about precautions – in relation to the badblocks command – was for this case, where questions surround both (a) goodness of hardware/media and (b) the cause of a kernel panic.

There, I hesitate to recommend badblocks (or any commercial alternative) … might effects of the command make future debugging/diagnosis more difficult?

Maybe I'm unnecessarily cautious. (I simply haven't tested badblocks with my own MacBookPro5,2 where CoreStorage is used to encrypt ZFS)
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Re: badblocks(8) with ZFS, with and without CoreStorage

Post by si-ghan-bi » Tue Oct 16, 2012 4:23 pm

Another option is to simply wait... first the HD will take care of them and later, if it fails, ZFS will do.
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