Which geom to use?

[Stanislav Sedov]

На Sun, 9 Jul 2006 17:57:59 +0200
Paul Schenkeveld <fb-geom at psconsult.nl> записано:

> Hi,
> 
> Some installations just need a lot of filesystems (e.g. systems with
> many jails) making geom_bsd a bad choice because it only supports
> 7 partitions.  So far I've been using vinum and gvinum for the task
> of dividing my disk which is also quite convinient for adding new
> partitions in so far unallocated space later on.
> 
> On systems with mirrored disks (or RAID5) this works fine but on
> systems with a single disk this approach has a very bad consequence:
> when a disk error occurs anywhere on the disk, all subdisk and thus
> all volumes on this drive object become invalid and the system
> crashes.
> 
> Another approach is to slice up the disk in MBR and divide each slice
> in 7 patitions with bsdlabel giving you 28 partitions to use and less
> freedom to re-allocate later on because it's a very hard job to change
> the MBR slices without doing a complete re-partitioning.
> 
> I've heard of people putting filesystems in files using md(4) but I
> fear the performance penalty of going through a filesystem layer
> twice.
> 
> So what would you guys recommend in this case, gpt(4)?  Or is there
> some kind of geom that does just the volume management of gvinum
> without marking all volumes down at the first media error?
> 

I was using gpt to handle 20+ partitions on 2TB array for a long
time with success. So it's well suited for this.

-- 
Stanislav Sedov         MBSD labs, Inc.         <ssedov at mbsd.msk.ru>
Россия, Москва         http://mbsd.msk.ru

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