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From: brtmac@maverick.ksu.ksu.edu (Brett McCoy)
Newsgroups: comp.unix.large
Subject: Re: Files > 4GB
Message-ID: <1990Nov10.190318.18938@maverick.ksu.ksu.edu>
Date: 10 Nov 90 19:03:18 GMT
References: <1008@intelisc.isc.intel.com> <1990Nov9.170337.9484@onion.pdx.com>
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In <1990Nov9.170337.9484@onion.pdx.com> jeff@onion.pdx.com (Jeff Beadles) writes:

>In <1008@intelisc.isc.intel.com> cfj@isc.intel.com (Charlie Johnson) writes:

>>I'm curious if the companies who support Unix on large systems made the
>>necessary file system changes to allow individual files which are larger 
>>than 4 gigabytes ??  You'd have to at least stretch the file size in the
>>inode beyond 32 bits and possibly mess around in the super block.  Any
>>comments ??

>Well, that would take one big disk :-)  Unix files can not span physical disk
>partitions, at least on more common version of Unix. (Has anyone changed this?)

Unless what I read recently is totally bogus, the latest version of AIX,
the version that is on the new RS/6000 machines, has support for spanning
filesystems across multiple disks.  It does this deep down in the kernal
so that to filesystem sees the multiple disks as a single volume.  It
actually has support for quite a few tricks including disk mirroring.
How much of this is actually usable right now I don't know, but supposedly
it does work.

There is also some company that sells either software or hardware for
Sun machines to do disk mirroring and disk spanning.  All I know about
this is what I saw in the one page ad.  I don't even remember the magazine
I saw it in anymore.

>This pretty well limits the file size more than the kernel internals.

No, it is the kernel internals that allows things like disk spanning, so
it is the kernel that limits things, not the physical disks themselves.

>Then again, the largest file that I've seen in "real-life" is a 247mb kernel
>core dump :-)

I quite regularly have 300-400M dump files.  I have to put them on tape,
broken up into multiple pieces, which makes it a pain when looking for a
file.  Being able to load these onto disk occasionally might make things
easier under the right circumstances.
--
Every day you scream at me to turn the music low.
But if you keep on screaming, you'll make me deaf, ya know. -- Judas Priest

Brett McCoy	brtmac@maverick.ksu.ksu.edu