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

Chris Hofstaedtler | Deduktiva chris.hofstaedtler at deduktiva.com
Sun Jul 26 23:55:42 CEST 2020


* Hermann <pve at 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 Hofstaedtler / Deduktiva GmbH (FN 418592 b, HG Wien)
www.deduktiva.com / +43 1 353 1707

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