Re: [PVE-User] FC-Luns only local devices?

[Chris Hofstaedtler | Deduktiva <chris.hofstaedtler@deduktiva.com>]

Hi,

* Hermann <pve@hw.wewi.de> [200725 18:05]:
> Could you explain in a short sentence, why you avoid partitioning? I
> remember running into difficulties with an image I had created this way
> in another setup. I could not change the size when it was necessary an
> had to delete and recreate everything, which was quite painful, because
> I had to move around a TB of Files.

I don't know about images, but we were talking about LVM PVs on top
of LUNs (SCSI disks from a Linux point of view).

Now, if the only thing that goes on the LUN is an LVM PV, why add an
extra layer, an MBR or GPT partitioning layer?

From my experience this adds two things:
1) another size definition, which you have to edit when resizing the LUN
2) another size definition, which is also read and cached by the
Linux kernel, and - at least in the past - was often impossible to
get updated without closing all open handles to the block device.
Effectively, this meant rebooting.

Also, local staff isn't too happy to fiddle with fdisk: delete and
recreate a partition to resize it. Or use parted and find the magic
flags so it doesn't actually do something unexpected.

Chris

-- 
Chris Hofstaedtler / Deduktiva GmbH (FN 418592 b, HG Wien)
www.deduktiva.com / +43 1 353 1707