[Info-vax] RAID vs. MOUNT/BIND

[Bob Gezelter]

On Nov 17, 8:19 am, koeh... at eisner.nospam.encompasserve.org (Bob
Koehler) wrote:
> In article <ic0cpb$6h... at online.de>, hel... at astro.multiCLOTHESvax.de (Phillip Helbig---undress to reply) writes:
>
> > I might need some logical disks bigger than any physical disks I have.  
> > Controller-based RAID is not an option (don't have enough controllers
> > for the needed redundancy), so the options are host-based RAID and
> > volume sets.  If the only point is to create a larger logical disk,
> > which is better?
>
>    Volume sets can spread files over two physical disks and make them
>    look like one, but cannot spread a single file over two disks.  So if
>    there is enough space on the pair for a new large file, but not on
>    either disk, it won't fit.
>
>    RAID can split a single file over multiple disks.

Bob,

Au contraire. Files can extend from one member of the set to another.
If I recall correctly, this will not happen simply because there is
more space on the other volume; but it will happen if there is
insufficient space available.

JF,

LDDRIVER had a bug. There are few programs that need to deal with
things at that level. Put another way, before the problem LDDRIVER I
do not recall that class of issue being mentioned.

Shadowing bind sets is not doable, each member remains accessible as a
distinct device. The unification is at the directory tree level. The
correct way is to create shadow sets (device level) and bind the
resulting volumes into a biund volume set.

- Bob Gezelter, http://www.rlgsc.com