disks without a GUID Partition Table (GPT)

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disks without a GUID Partition Table (GPT)

Post by grahamperrin » Tue Oct 16, 2012 12:50 am

Spun off from multiple topics

dbrady wrote:The import code is filtering for disk slices. It's possible you can work around this by creating a symlink whose name looks like a disk slice. I haven't tested this, but it's an easy experiment to try …


Example

If the disk that comprises a pool is like this (without a GUID Partition Table) –

Code: Select all
/dev/disk1
   #:                       TYPE NAME                    SIZE       IDENTIFIER
   0:                                                   *1.5 TB     disk1


– then for as long as that disk will be number 1, you might workaround with this symlink:

Code: Select all
$ sudo ln -s /dev/disk1 /dev/disk1s2


Please note

ZEVO Community Edition 1.1.1 is designed to work with GPT UUIDs.
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Re: disks without a GUID Partition Table (GPT)

Post by dbrady » Thu Oct 18, 2012 7:39 pm

Please note that using disks without a label (ie without a partitioning scheme) is a really bad idea. The OS X model of disk discovery (probing) is built on the assumption of labeled disks.

Since each file system has different disk layouts, its possible to simultaneously have two different file systems on an unlabeled disk (from a probe standpoint). Think about what happens when you create one file system then create a different one over the previous one! Unless you intentionally wipe out all identifying marks of the first one, it can pass a probe of the prior file system. With multiple platforms and file systems out there, I wouldn't rely on any single file system creation call to correctly remove the prior occupant. Using explicit container typing (i.e. using partitions) helps avoid these type of cross file system corruptions. I have seen enough of these to know that it's a real problem and it's typically very destructive.

For ZEVO we recommend only using GPT partitions to hold ZFS content for use with OS X.
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Re: disks without a GUID Partition Table (GPT)

Post by grahamperrin » Thu Oct 18, 2012 9:44 pm

Thanks – very educational.

Should users of TrueCrypt view as risky any part of a transition from JHFS+ without a partitioning scheme to ZEVO with a GPT?
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Re: disks without a GUID Partition Table (GPT)

Post by grahamperrin » Mon Oct 29, 2012 3:30 pm

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Re: disks without a GUID Partition Table (GPT)

Post by daniel.jozsef » Mon Oct 29, 2012 9:10 pm

I beleive CREATING new zfs devices without labels might be a really bad idea, but sometimes you just need to access some Linux-generated zfs drives, and those are unlikely to have labels... Having access to data is always better than not having access to it. XD
BTW, how do other operating systems fare with GPT-based disks, I'm wondering esp. about Linux and Solaris...

As for the opening question, yes this does in fact work, but make sure to remove the symlinks afterwards... And never forget that you have drilled a hole into OSX. It's safe as long as you know what you are doing.
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assistants (idea)

Post by grahamperrin » Tue Oct 30, 2012 1:49 am

I imagine:

  • that we should not cram too much into the ZEVO pane of System Preferences (keep it lean – now is too soon to predict what users might want from the pane in years to come)
  • in the future, a small variety of assistant apps, which may be launched from within the pane.

Where a disk for a pool is without the expected partitioning scheme

An assistant might help.

Does that sound reasonable?

If you have any GUI ideas for an assistant for this purpose, please share – thanks.
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zfsonlinux issue 94

Post by grahamperrin » Mon Dec 31, 2012 4:21 am

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