RE: gpt caching?
RE: gpt caching?
- Subject: RE: gpt caching?
- From: "Freeman, Andrei" <email@hidden>
- Date: Thu, 28 May 2009 10:46:18 -0500
- Acceptlanguage: en-US
- Thread-topic: gpt caching?
Hi Chris-
Definitely referring to the GUID here. diskutil lists this in the Type column. Typically this lists the GUID in descriptive form: Apple_HFS, EFI, Apple_Boot. In cases where you are supplying your own driver with its own GPT GUID, the GUID displays at length.
The issue in question comes when modifying the GPT info for a volume's GUID in the GPT (or in the MBR when dealing with legacy boot systems). The GUID is easily modified for a volume, but it would seem that this information is cached. Thus, if I try to convert from my driver's GUID to the HFS GUID, the drive is correct, but diskutil is working off of cached information. Thus if I want to call a resizeVolume on the disk (even if it is HFS) diskutil doesn't believe me or the stored GPT info on the drive.
What I need to do is to tell the mechanism that reports to diskutil, "Hey, your info is out of date."
-Andrei
On Wednesday, May 27, 2009 10:51 PM, Chris Suter replied
Hi Andrei,
On Thu, May 28, 2009 at 2:24 AM, Freeman, Andrei
<email@hidden> wrote:
> Is the GPT information cached for the boot volume? I find that if I change
> the GUID in the gpt for a volume that is mounted that diskutil does not see
> the change.
>
> This is especially a problem if I am changing a drive on the fly and wanting
> to resize the volume in diskutil (requiring HFS flavoured GPT GUID)
It's possible that you're getting confused with the different UUIDs
that are used. diskutil lists the "volume" UUID which is different
from the UUIDs that are used in the GUID partition scheme. The volume
UUID for HFS+ filesystems is stored within the filesystem, not as part
of the partition table.
Kind regards,
Chris
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