SUMMARY: AdvFS Information

From: Surash Natarajan <SURASH_at_omc.otis.utc.com>
Date: Mon, 24 Jun 1996 20:04:00 -0700 (PDT)

Thanks to the following people which responded, namely:
Robert.Schuhl_at_ald-vt.de
N.M.Hill_at_rl.ac.uk
alan_at_nabeth.cxo.dec.COM
labelles_at_mscd.edu
soma_c_at_decus.fr

Below are some of the responses :-
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This information is typically in the Software Product Description
though it might also be in the Technical Guide. From the V3.2C
SPD, the maximum file size for AdvFS is 128 GB. This limit is the
result of knowing what works through testing. I think the arch-
itectural limit is multiple terabytes. With a file size that
large the maximum domain size has to be at least as large as
does the underlying domain.

In V4.0 this limit is raised, but I haven't seen the V4.0 SPD
to see what the limit is.

Multiple filesets allow segregation of file systems. Each
file set has equal access to space of the domain, so a large
file set will use what it needs. On the other hand a single
fileset clearly has access to all the space anyway. But the
single fileset means putting all the users under a single
mount point.

A single fileset will have to be backed up at once, where multiple
filesets can be backed up separately. This could affect how you
do backups.

alan.
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I do not know the maximum size of an ADVFS, I have never seen it documented?

I can tell you this, I have a 2 RAID sets (5 RZ29b's) in a storageworks
cabinet. After accounting for the disk overhead to support RAID, I have some
16.3 GB's. I have two different ADVFS file systems using that space 16.3 GB.
I have had no problems.

I suggest you study about the metadata extent table used with ADVFS
domains. There are some issues with having a very large number of files
on a ADVFS domain, like 400,000+ causing problems if you do not keep the
ADVFS file system defragmented.

Thats the largest I have tried I believe it could be much bigger. The
problems with real large filesystems is how are you going to do your
backups?

It really depends on what you are doing as to whether you want just a few
very large file systems or whether you want many small file systems.

You might also put smaller file systems together with LSM.

I have not really answered your questions directly. Hope my info help
anyhow.

 Steve
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I'am using advfs and here is what i think:

 -a large domain is not easy to manage
when you make a clone (for backup)
if there is activities on the file system then your domain grow because
the clone goes into your domain. (you can't choise)

If the domain crash, (some times this can appen because of BUGS)
you must restore large data.

If you can put an application in one domain, the other in an other etc ...
I think that 's good to separate, then if one domain crash, only the
application on this domain must be restored.

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I do not knwon what the maximum domain size is but I believe the maximum
AdvFS
fileset size is 128gb

Nick Hill

+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
CISD, Rutherford Appleton Laboratory, Tel: +44
(0)1235-445598
Chilton, Didcot, Oxon, OX11 0QX, England. Fax: +44
(0)1235-446626

N.M.Hill_at_rl.ac.uk
           http://www.cis.rl.ac.uk/people/nmh1/contact.html
+++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
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We use ADVFS in conjunctions with a RAID-controller with 16GB no having =
any problems.

Robert
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 xxx x xxx Robert Schuhl
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x x x x x 63526 Erlensee, Germany
 xxxx xxx xxx Tel: +49-6183-883211 Fax: +49-6183-883215
                office: Robert.Schuhl_at_ald-vt.de;http://www.ald-vt.de
                priv: rschuhl_at_rsl000.rhein-main.de
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Below is my original question :-

>>Hi,
>>
>>Does anyone know what is the maximum size for a file domain in AdvFS. I
have
>>gone through the documentation for AdvFS and it is not mentioned anywhere.
I
>>would also like to get any information on experience faced in having one
>>large file domain against having multiple smaller file domains.
>>
>>Any reply will be much appreciated.
>>
>>Regards,
>>
>>Surash Natarajan
>>OTIS Engineering Center - Penang, Malaysia
>>surash_at_omc.otis.utc.com
Received on Tue Jun 25 1996 - 10:22:41 NZST

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