[rhelv6-beta-list] My first experiences with RHEL6 beta

[Chris Adams]

Once upon a time, Bryan J. Smith <b.j.smith at ieee.org> said:
> Now isn't that far more efficient?  It certainly is more manageable
> to leverage LVM2/DM than to try to move around a "swap file" in a file
> system.  The filesystem slice still looks like a single, linear slice,
> even though it's physically not.  Same deal with the swap partition.

IMHO the biggest drawback with LVM and filesystem changes right now on
Linux is that you cannot shrink a mounted filesystem (at least not
ext*), only expand.  That makes many live changes such as re-allocating
space from one use to another impossible.  You can re-allocate free
space, but not in-use space.

With a swap file, you can create a new file on another filesystem,
swapon the new file, and swapoff an old file, essentially moving free
space in one filesystem to another.  You can't really do that with a
swap LV.

Now, am I using swap files?  Nope.  However, I can see advantages to
them (and I _do_ make good use of Linux LVM).

> [ SIDE NOTE:  Linux LVM is modeled after Digital UNIX/Tru64's
> volume manager ]

Really?  I've used DECs for years and didn't know that.  Looking around,
I see why: DEC killed "LVM" in favor of "LSM" a long time ago, and
Linux's LVM is based on DEC's old-dead-LVM (which I never used).  Yay
for copying what somebody else abandoned. :)

Wasn't Linux's device mapper layer created by (IIRC) IBM for use with
their logical storage/volume management system (which never made it into
Linux), and then Linux's LVM 1 ported to DM?

-- 
Chris Adams <cmadams at hiwaay.net>
Systems and Network Administrator - HiWAAY Internet Services
I don't speak for anybody but myself - that's enough trouble.