Date: Tue, 27 Jan 1998 23:14:41 -0600 (CST) From: James Wyatt <jwyatt@rwsystr.RWSystems.net> To: Andrew Webster <andrew@guardian.fortress.org> Cc: Norman Hoy <normh@aone.com.au>, lamaster@george.arc.nasa.gov, freebsd-isp@FreeBSD.ORG Subject: Re: Sendmail - low on space Message-ID: <Pine.LNX.3.91.980127224514.13089B-100000@rwsystr.RWSystems.net> In-Reply-To: <Pine.BSF.3.96.980127165831.21902I-100000@guardian.fortress.org>
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On Tue, 27 Jan 1998, Andrew Webster wrote:
> On Wed, 28 Jan 1998, Norman Hoy wrote:
> Of course what would be REALLY nice would be a virtual disk driver like
> AIX's JFS where you can just keep adding disks when you run out of space
> on the logical volume!
>
> Oh well, we can at least dream...
[ much else deleted, cause I use a tty, not a window... 8{) ]
I *love* this feature more than I can tell. Your OS installs with the
needed partition sizes, leaving the rest of the disk 'uncommitted'. The
install process expands them by the amount they need for each package.
When you get paged on a low disk space alarm, you can just sprinkle some
more space on whichever filesystem is low. It adjusts the mirroring and
striping drives' partitions too! If you do not realize what you are doing,
it can easily lead to hopelessly fregmented drives, so don't grow by small
amounts.
You can grow them while users are going at things full blast, but the new
mirror can take a few minutes to catch-up. You can only grow, not shrink.
It is *very* easy to get used to this power tool! I use several of
different unicies, but AIX is the only one I've used with this. Doesn't
someone else like HPUX or OSF/1 have something like this?
Another nice feature is SSA (Serial SCSI Array?) drives allow multiple
machines to access the same sets of drives to improve process-takeover in
fail-over systems. If a box goes, it's sibling grabs it's drives, ARPs
for it, and starts whatever processes it needs. Users see a few seconds of
pause and then it just works again - while you fix the hardware in peace!
We have lost systems and not realized it for hours.
A take-over scheme like this could work on FreeBSD if you could have two
machines share a SCSI-UW bus with some drives. Target-mode SCSI sould
allow the machines to exchange info on who had what drives. Any takers? (^_^)
Of course, when we tried to use DCE to make some nice client-server
systems, we found the software didn't scale as well as the hardware... Oh
well, at least DCE had decent RPCs and DNS still works!
James Wyatt (jwyatt@rwsystems.net jwyatt@rwsys.lonestar.org) KA5VJL
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