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From: drake@drake.almaden.ibm.com
Newsgroups: comp.unix.aix
Subject: Re: AIX vs standard unix
Message-ID: <822@rufus.UUCP>
Date: 5 Jun 91 06:42:02 GMT
Article-I.D.: rufus.822
References: <1991Jun3.173646.25682@ux1.cso.uiuc.edu> <11640@ncar.ucar.edu> <1991Jun4.163505.29244@cs.utk.edu>
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Organization: IBM Almaden Research Center
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In article <1991Jun4.163505.29244@cs.utk.edu> Dave Sill <de5@ornl.gov> writes:
>In article <11640@ncar.ucar.edu>, pack@acd.uucp (Daniel Packman) writes:
>>
>>I'd take the journaled file system over sys V or berekely any day.
>
>How about the day one of your disks crashes?  Like, maybe the one
>that's got pieces of /, /usr, /u, etc. on it, and instead of restoring
>one drive's worth of stuff, you have to restore everything?

Well, there are tradeoffs in everything.  For many people, the idea that
you can expand filesystems dynamically into any unused disk space on any
drive is a Big Win.  The potential downside, of course, is the situation
that you've mentioned.

If this is a real concern for you, it's easily fixed.  Make each disk
drive in your system a separate "volume group", instead of putting all
volumes in the same volume group ("rootvg" is the default).  

A logical volume (read: "filesystem") resides in one and only one volume
group.  If all of your disk drives are in the same volume group, then as
you mentioned each drive may wind up with a bit of each filesystem.
If you make each disk drive a separate volume group, on the other hand,
then you always know exactly what filesystems are on each drive.

Naturally, this gives up much of the beneficial flexibility of the
logical volume manager that was so nice in the first place ... but 
if this issue really concerns you then I'm sure you'll be happy to know
that it need not be an issue.


Sam Drake / IBM Almaden Research Center 
Internet:  drake@ibm.com            BITNET:  DRAKE at ALMADEN
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