I asked about the implications of setting up one AdvFS domain over
several volumes (3) including /usr, /var, /users, /usr/local, etc.
The full text of the question appears below.
All replies save one, encouraged this setup. The last three people
listed below are using very similar setups with no problems. I have,
in fact, implemented this and have not yet encountered any adverse
effects.
The only negative response I received was from Paul Rockwell. I was
somewhat surprised to receive such a negative evaluation of the AdvFS
from a Digital representative, however, since Paul is a professional
Digital support person, I considered his comments very seriously. In
the end, I decided that most of his reservations were not relevant to
our particular case. I should add that I also discussed them with our
local Digital Software Support contact, who agreed with my point of
view. Nevertheless, I include Paul's comments below for anybody else
who may be considering this. Other specific comments are available on
request.
Many thanks to:
Knut Helleboe <Knut.Hellebo_at_nho.hydro.com>
Paul Rockwell <rockwell_at_rch.dec.com>
Ohad Imer <ohad_at_comport1.comport.com>
Lucien HERCAUD_at_PB_PARIS_at_PARIBAS.COM_at_SMROUTER
Dougal Scott <dwagon_at_aaii.oz.au>
Gary Arnold <gary.arnold_at_hri.ac.uk>
Carlos A M dos Santos <ufpelrm_at_eu.ansp.br>
> I have the following setup in /etc/fstab:
>
> /dev/rz3a / ufs rw 1 1
> /proc /proc procfs rw 0 0
> /dev/rz3b swap1 ufs sw 0 2
> /dev/rz3d /var ufs rw 1 2
> /dev/rz3g /usr ufs rw 1 2
> advfs_domain#users /users advfs rq,userquota,groupquota 1 2
> advfs_domain#tex /Tex advfs rq,userquota,groupquota 1 2
> advfs_domain#local /usr/local advfs rq,userquota,groupquota 1 2
> .
> .
> .
>
> The advfs_domain spans two volumes, /dev/rz3h and /dev/rz8c. I am
> getting a new disk and would like to take the opportunity to change
> my set up to the following (i.e. rz3 will then be partitioned as
> a,b,g and /dev/rz3g will be added to the advfs_domain):
>
> /dev/rz3a / ufs rw 1 1
> /proc /proc procfs rw 0 0
> /dev/rz3 swap1 ufs sw 0 2
> advfs_domain#var /var advfs rw 1 2
> advfs_domain#usr /usr advfs rw 1 2
> advfs_domain#users /users advfs rq,userquota,groupquota 1 2
> advfs_domain#tex /Tex advfs rq,userquota,groupquota 1 2
> advfs_domain#local /usr/local advfs rq,userquota,groupquota 1 2
> .
> .
> .
>
> The point is that I want to get away from the traditional ufs
> restrictions of fixed partition sizes and be able to change the size
> of /usr (or /var or whatever) as the need arises within the restriction
> only of my total available disk space, i.e. the advfs_domain. I would
> very much appreciate any comments from people who have experience, good
> or bad, with this type of arrangement, in particular, with including the
> usr and var filesets within a general domain, along with users, etc.
> Can anyone think of any compelling reason not to do this?
>
> Thanks in advance,
>
> Peter Stern
> Chemical Physics Department
> Weizmann Institute of Science
> 76100 Rehovot, ISRAEL
>
----------------------------------------------------------------------------
Date: Wed, 27 Mar 1996 10:46:36 -0500
To: Peter Stern <peter_at_wiscpa.weizmann.ac.il>
From: Paul Rockwell <rockwell_at_rch.dec.com>
Subject: Re: /usr and AdvFS
Status: RO
At 08:48 AM 3/27/96 +0300, you wrote:
>The point is that I want to get away from the traditional ufs
>restrictions of fixed partition sizes and be able to change the size
>of /usr (or /var or whatever) as the need arises within the restriction
>only of my total available disk space, i.e. the advfs_domain. I would
>very much appreciate any comments from people who have experience, good
>or bad, with this type of arrangement, in particular, with including the
>usr and var filesets within a general domain, along with users, etc.
>Can anyone think of any compelling reason not to do this?
Personally, I wouldn't do this. Although you may gain some flexibility
I can think of several reasons why this isn't so hot:
1) Performance. You are throttling all activity against the single domain,
and could possibly thrash the disks depending on the I/O load.
Also realize that all your file sets now share the same AdvFS log and
allocation bitmap. Those now can become bottlenecks.
2) Backup. If you're using NSR to back up the domain, it won't back up
items in the domain in parallel (one backup to the domain at a time). Other
methods of backup have the possibility of poor performance (you are thrashing
again).
3) Recovery. You increase the chance of a failure in the domain with multiple
disks. So, a disk crash (or other failure) in one of the disks takes out the
*whole* domain. You will have to recover the whole domain.
4) Storage management. It's easier for one of the other file sets to take
up the remaining space in the domain the way you want to set this up.
Not so great if you put system-level stuff in with user files. Filling up
the domain that also contains /var could cause all sorts of strange and
wonderful things to happen to your system. Putting user files on a separate
domain gives you more protection against this kind of thing happening.
--------
+---------------------------+ Paul E. Rockwell
| | | | | | | | Northeast Region SBU Technical Support
| d | i | g | i | t | a | l | Digital Equipment Corporation
| | | | | | | | 500 Enterprise Drive
+---------------------------+ Rocky Hill, CT 06067 USA
http://www.digital.com Internet: rockwell_at_rch.dec.com
Telephone: (860) 258-5022
Received on Mon Apr 08 1996 - 11:52:35 NZST