On Fri, 23 Jun 2000, J. Buck Caldwell wrote:

> Is there a primer out there on File System types? Most of my systems
> just use FFS, as I suppose is normal, but I'm wondering about all the
> other types and what thier benifits and shortcomings are.
> 
> In particular, I'm wondering if Unix has something along the lines of a
> NT Volume Set or Stripe Set. Sort of a RAID with no RAID controller.
> 
> Perhaps I should elaborate: I have a VAX4000/200 with over 100G of SCSI
> drives, most in 2G, 3G, 4G, and 10G differential format. I also
> (luckily) have enough differential SCSI controllers to put them all
> online. However, I don't want to be limited to 2G FFS file systems. What
> I want to know, is can I take (say) 5 10G drives, and create a file
> system that spans the drives, effectively giving me a 50G file system?
> The obvious question would be, if it can be done, do all the drives have
> to be on the same controller, or can there be a speed boost given by
> splitting them up over multiple controllers?

Check out raidframe.  If you've got your 4000/200 booted with a recent
kernel, then raidframe should work for you.  It will allow you to do
software raid 0, raid 1, and raid 5 (as well as combinations).  Basically,
it grabs a bunch of raw partitions, performs its processing (raid 0, 1 or
5) then presents another raw partition to you.  This should allow you to
create _large_ partitions, over which you can create the fs of your
choice.  "man -k raidframe" should turn up some goodies.

And if you can split the drives over controllers, that's usually a good
thing (tm).  Beware, however, that qbus is probably a limitting factor
here... even if you're talking fast SCSI, it still has to pass through
qbus speeds on its merry walk towards kernel/application land.

Hope this helps,

-Jon
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