At 9:55 AM 2/22/93 -0600, Doug Engert wrote:
>A few weeks ago, I asked if anyone had experience with optical
>disks and AFS. I got two answers, which indicated that thrashing
>of mounted disks would be a problem and that there were some
>problems with the size and number of /vicep* partitions.
>
>Since then I have been in contact with Andataco, a company
>selling a line of optical jukeboxes with a 1 GB cache disk. They
>use a software program called AMASS.
>
> "AMASS Multi-Platter, Virtual File Management Software treats the
> jukebox as one big disk. It is unique in its ability to provide
> direct access combined with a single device, single filesystem
> view of the system. This relieves users and applications of the
> burden of tracking media volumes and file locations. ... It is
> compatible with all host network protocols."
>
> "AMASS is implemented at the virtual file system (VFS) layer of
> the host operating system and is transparent to other software
> programs."
>
>The above are quotes from sales literature I received recently.
>
>This system look very attractive as a location for the /vicep*
>partitions. The cache disk looks very atractive as it would cover
>up any thrashing problems which might arise. You could get the
>best of both worlds, large cheap storage with AFS distributed
>caching and security.
>
>But there are some unanswered questions. Since AFS changes fsck,
>that implies that there is something different about the way AFS
>uses the /vicep* file systems.
>
>My questions are:
>
> Does anyone have experience with the AMASS software?
>
> Does anyone see a problem with using a file system implemented at
> the VFS level for AFS partitions?
>
> I know AFS 3.2 has a limit on the number of partitions, but is
> there a limit on the size of each partition? Somewhere I heard
> there may be a 2GB limit on the partition size?
>
> Douglas E. Engert
> Systems Programming
> Argonne National Laboratory
> 9700 South Cass Avenue
> Argonne, Illinois 60439
> (708) 252-5444
>
> Internet: [EMAIL PROTECTED]
AMASs might work but it is a waste of money to use it. See the response
that I sent you last time.
ALso, TransArc has confirmed that AFS has a 2 GB partiton size limit. They
think that the 26 partiton limit may be lifted in the next release. See
the message below.
Date: Mon, 8 Feb 1993 09:25:02 -0500 (EST)
From: [EMAIL PROTECTED]
To: [EMAIL PROTECTED] (Ron Levin)
Subject: Re: Optical Disks as AFS Partitions
Excerpts from mail: 8-Feb-93 Re: Optical Disks as AFS Pa.. Ron
[EMAIL PROTECTED] (2580)
> The cost per megabyte keeps dropping with the size of the jukebox (a 90 GB
> , 4 drive HP is $1275/Gb) but it cannot be used directly with AFS because
> of the 26 partition limit and 2 Gb per partition limits.
Precisely. I expected that the cost/MB would be less with larger
jukeboxes, I just wanted to see how much, to see how much data you need
to have before it becomes cost-effective.
The 2 GB/partition limit is fundamental, I think. It's an artifact of
the interface: the section 2 routines all take "int" offsets and return
signed values. We'd have to really overhaul the file server to
eliminate that.
The 26 partition limit is apalling. We should be able to fix that
(well, up to 255 partitions, anyway). But it looks like you have to
need to store (or plan to store) 75-100 GB to even bother.
