Very Computer

I'm relatively new to SGI (it's been about 7 yrs since my last
encounter).  I recently, inherited administration to 3 Irix's running
5.x.  All machines are installed with one file system per disk.
Example:  / and /disk02

Question: is this standard for SGI?  I know that in the HP world many
people recommend the one-file-system-per-disk approach.  Does SGI too?
If so what are the advantages of one FS as opposed to several smaller
ones, all mounted under root?  I'm inclined to backup, blow away, and
reinstall, but I would like to know if I'm missing some significant
advantage first.  Any thoughts appreciated.  Thanks

:I recently, inherited administration to 3 Irix's running
:5.x.  All machines are installed with one file system per disk.
:Example:  / and /disk02
:
:Question: is this standard for SGI?  I know that in the HP world many
:people recommend the one-file-system-per-disk approach.  Does SGI too?

Since IRIX 5.0, SGI has installed by default into a single filesystem.
The advantage of this is easier administration for the large number of
users who "just want it to work" without having to get in a trained
system administrator. You save a bit on problems with fsck'ing /usr
after a crash, and you save trying to explain to someone why they have
free space on their disk that they effectively can't get at.

The disadvantage of a single filesystem is that you lose the ability
to establish barriers to prevent some kinds of events from filling
up the entire disk and so effectively bringing the system down.
It is, for example, sometimes comforting to know that barriers are in
place to prevent irate netizens from filling up your entire disk by
'mailbombing' your system. Perhaps even more common, on multi-user
systems it is sometimes necessary to put disk hogs into separate
partitions to limit their excesses. And there is always the
possibility that someone will accidently start a program that infinite
loops producing output and thus eventually filling up the disk no
matter how big it is.

I wouldn't readily run a multiuser system without multiple partitions...
but our single user systems work fine with the single partition approach.

=> I'm relatively new to SGI (it's been about 7 yrs since my last
=> encounter).  I recently, inherited administration to 3 Irix's running
=> 5.x.  All machines are installed with one file system per disk.
=> Example:  / and /disk02
=>
=> Question: is this standard for SGI?  I know that in the HP world many
=> people recommend the one-file-system-per-disk approach.  Does SGI too?
=> If so what are the advantages of one FS as opposed to several smaller
=> ones, all mounted under root?  I'm inclined to backup, blow away, and
=> reinstall, but I would like to know if I'm missing some significant
=> advantage first.  Any thoughts appreciated.  Thanks

        This is something I've debated with many administrators.
Here's the points that always come up:

Against Single FS:
        - If you build a filesystem over many disk, losing any of
          those disks means all the data on all the disks is gone.
        - Without having system directories on a separate
          filesystem, a user can fill up the filesystem and cause
          the entire system to mess up.  A big problem with a
          multi-user system.
        - If you add disks and go over 8GB, you have to
          re-install everything using XFS.
        - It's more difficult to backup user files without
          getting the OS too.
        - The fsck recoveries after a crash often take longer.

For Single FS:
        - You don't end up with idle disk space.
        - It's easier and faster to set up.
        - It's the way SGI does it, so you won't have to
          re-install each new machine.
        - You can increase disk i/o with striping a single
          filesystem across several disks.
--
Jason C. Austin

WWW:   http://gis-www.larc.nasa.gov/~jason

:       This is something I've debated with many administrators.
: Here's the points that always come up:

: Against Single FS:
:       - If you build a filesystem over many disk, losing any of
:           those disks means all the data on all the disks is gone.
:       - Without having system directories on a separate
:         filesystem, a user can fill up the filesystem and cause
:         the entire system to mess up.  A big problem with a
:         multi-user system.
:       - If you add disks and go over 8GB, you have to
:         re-install everything using XFS.
:       - It's more difficult to backup user files without
:         getting the OS too.
:       - The fsck recoveries after a crash often take longer.

Add one more to the against list (found this one out recently):
After a crash or reboot, the log for the automatic fsck on the / partition is
lost, since it can't write to the /etc/fscklogs directory.
Not a big deal with mutliple partition disks.
But it means you lose all of your fscklogs if you only have one partition.
Unless they hide it somewhere in the swap space, but tech supp didn't know of
any such technique.

We recently had a machine blow up.
When fscking it cleared some files out of /usr.
We had no way of knowing what they were, other than waiting for the user to
tell us they couldn't run xxxxx.
We had to remake the filesystem and restore the whole thing from exabyte, for a
handfull of files.

Needless to say, we are in the process of changing our 1 partition machines
back to multiple partitions.

mike
--
Michael J. Messina
Network and Systems Administrator       | The Walt Disney Studios