I've gotten to the point where I won't recommend to anyone that they put
their root partition on RAID/LVM/what have you.  I would make my root
partition ext2/3 (including /etc and /boot), and have the rest be either LVM
or RAID.  RAID if you don't anticipate having to add/remove a particular
volume from the array.  LVM if you do.

As Adam pointed out, this might be a good candidate for access your storage
array as an open systems device, and just carve out a big enough piece to
hold all of /usr.


Mark Post

-----Original Message-----
From: Jim Sibley [mailto:[EMAIL PROTECTED]
Sent: Thursday, September 04, 2003 12:32 PM
To: [EMAIL PROTECTED]
Subject: size of distributions (redux)


Sorry for the shortened post just now. This is the
complete post:

I've been playing with several of the new
distributions and they have one thing in common - the
size of the /usr directory is growing rapidly. In
early distributions, you could contain a zLinux system
on one 3390-3 image. Now, its taking two or three if
you need to install all the development libraries.

I am reluctant to go to larger volume images because
larger images put more data behind a subchannel and
since zLinux does not support PAV's there is a
potential performance bottleneck for the I/O.

So far, I have tried 3 approaches to contian the
problem:

1) two volume images, but /usr is 70-80% full and does
not allow for growth:
     /dev/dasda1   /
     /dev/dasdb1  /usr

2) three volumes seems to be a bit better
    /dev/dasda1 /
    /dev/dasdb1 /usr
    /dev/dasdc1 /usr/share     (uses /usr/share as a
mountpoint)

Approaches 1 and 2, I would suspect, would grow in
complexity as the distributions grow.

3) a combination of raid and real partitions. This
improves performance and the size of the system volume
but does it lead to recovery problems? I have put /etc
on a "real" partition so that the systems parms can be
accessed directly for recovery, especially
/etc/raidtab.

       /dev/dasda1 /boot
       /dev/dasda2 /etc
       /dev/dasda3 swap
       /dev/md0    /       (raid0)
               /dev/dasdb
               /dev/dasdc
               /dev/dasde

Given that larger images beyond 3390-3 can be
performance problems w/o PAV's, what are the pros and
cons of the above 3 approaches? Are there other
approaches to setting up the system. (All three
methods, above, can be done during the initial cd-rom
install).

=====
Jim Sibley
Implementor of Linux on zSeries in the beautiful Silicon Valley

"Computer are useless.They can only give answers." Pablo Picasso

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