Filesystem Structure of HP-UX in a SAP Environment

[Robert Miller_4]

I am trying to get an idea how others configure there file systms on a SAP server running HP-UX. We currently have the /tmp direcotry and the /var directory in the root (/) file system. Is anybody else doing this? I would like both yes and no comments as I will be polling the numbers.

I always thought that /tmp and /var should be in there own filesystems.

Thanks in advance.

[Naveej.K.A · Accepted solution]

recommended to have /tmp and /var in different filesystems. Have seen all those SAP production servers the same way only

best wishes
naveej

[Mark Grant]

Definately have them as separate filesystems. /var and /tmp are very easy to fill up. If they are just directories in the root filesystem, your root filesystem will fill up and you don't really want that.

[Robert-Jan Goossens]

Hi Robert,

No /tmp and /var have own filesystems on our systems. / is rather small about 250 MB /var about 1 gb and /tmp about 250 mb.

Regards,
Robert-Jan

[Pete Randall]

Robert,

Whether it's a SAP server or not, I would never have /tmp and /var under the root file system. The root file system should be nearly static - it should vary extremely little in size from day to day - there should be virtually no activity in it. Making your /tmp and /var into separate file systems allows you to isolate their volatility from affecting /.

That's really the *only* way to do it.


Pete

[Shaikh Imran]

Hi,
I am configuring the /var as 1.4GB and /tmp as 1gb and a seperate filesystem on my SAP R/3 production Server.
And i will also advise you to do the same.

[Jeff Schussele]

Hi Robert,

Of course /var & /tmp should be their own filesystems, BUT /tmp should *not* need to be large. /var/tmp should be where applications & users place temp files & *only* there. /tmp should really only be used by the OS for it's temp file needs.
We set our /tmp to 256 MB & /var in the 1-3 GB range depending on needs. We also set /var/adm/sw to it's own FS so the SD utils won't fill /var & impact apps.

Rgds,
Jeff

[Marco Santerre]

I'll agree with Pete on that one, whether you have an SAP server, or any other server for any other purposes, /var and /tmp should definitely be separate from the / filesystem.

I like my /tmp to be usually fairly small around 200-300 Mb.. but my /var to be a little bigger, usually closer to 1 Gb..

[Robert Binkhorst]

Hi,

We also seperate these into different file systems, /tmp 512Mb, /var 2Gb.

You really don't want one of these to fill up and to be in the way of the other.

HTH,

Robert

[Bill Hassell]

The default installation for HP-UX ever since the introduction of LVM for disk partitioning has always had /tmp and /var (as well as /usr and /opt) on separate filesystems. The reason is easy to explain: reliability! /var is perhaps the MOST critical filesystem in HP-UX. If it fills, all logging operations including syslog will halt or crash, and most non-trivial processes will halt or crash because they cannot continue to run.

The V.4 filesystem standard is more than a decade old and defined /tmp as opsystem-only, thus the reason for having it smaller (about 100-300 megs). Unfortunately, there are a lot of old scripts (or maybe old script writers) that didn't get the word that /var/tmp is the 'new and improved' general-purpose temp area.

Anyways, /var should be quite large (think gigabytes) or better yet, subdivided into subsystem-related lvols. The reason you want /var subdivided is that a specific subsystem such as email or spooling can fill /var, thus taking down your computer. That's not good. Now not everyone runs email or spooling so you have to look at what is the most variable (/var, get it?) and give it a separate lvol. That way, if /var/mail is a separate volume, a denial of service attack in the form of massive email messages will not take down the rest of your system. Similarly, an untrained user that tries to print a big file (over and over) to a printer that is out of paper, will also fill /var.

So I would suggest making the following /var directories into separate lvols to prevent a small problem from affecting the entire system:

/var/tmp (anyone can dump things there)
/var/adm (virtually all logfiles)
/var/adm/sw (patch and install backups)
/var/adm/crash (kernel crash dumps)
/var/mail (email)
/var/spool (printer jobs)
/var/opt/ignite (Ignite/UX depots)

And this also implies that / is quite small, perhaps 150 to 300 megs. If it is very large (500 megs or more), you probably have rogue applications that created their own install and/or data directories without permission from the system administrator. These directories should be moved out of / because / is defined as a STATIC directory--never changes. And for the same reason as /var...it is too critical to have uncontrolled applications filling up /.