multi disk vg, Eloquence space

[jp]

Currently we have an 18gb base disk, all vg00, normal set of lvols on it, and an unused (as reported by SAM) 18gb drive. We need to expand /var to increase space available to Eloquence.
Two questions - is it mandatory for Eloquence to use /var - can I put it on an lvol that does not require booting to single user to maintain size? If not, how? If so, can I, and should I, add the unused volume to vg00, and expand /var onto it? What is the accepted method for handling things like this, where space requirements are unpredictable?
TIA,
jp

[Michael Tully]

Normally a second internal disk (this is what I suspect you have not knowing the model you have or the hardware address) is used for mirroring. If this is a dev box box, many people don't mirror internal disks and use it for something else. You really have two options.
1) add this disk to /dev/vg00 and use it there.
2) Create a new volume group and use it there.

Whether it is mandatory is up to the application, but most do not. If it is you could create a symbolic link from your application default directory. This is done quite a lot for OmniBack databases on HPUX.
If you create the directory on a different mount point and name, then yes it is easy to handle and it is not used during single-user mode.

[Steven E. Protter · Accepted solution]

Most tools provide you flexibility for where to put log files.

Unix convention and the idea of the sysadmin that helps out when you're on vacation say put the log files in /var because thats what its for.

If you have unused disk space on vg00, you should be able to expand var onto it.

lvextend /dev/vg00/lvol# -L /dev/dsk/c1t1t0

replace the # with the actual value for /var off a bdf display and the disk you want to expand it onto.

There are actually some interesting schools of thought with regard to the /var filesystem.

Some have a big old massive /var and let everything log into it.

Bill Hassell suggested at a class at 2004 HP World that this was not a great idea. If the print spool that ususally defaults to /var fills up the whole system halts.

He suggests that you may want to create mountpoints under /var for various system logging functions. That way if something fills up the system doesn't halt.

This might help you. You can expand vg00 onto a new disk and create a filesystem called /var/eloquence. It looks like its on /var but its really not. Its its own filesystem non its own disk of any size you need.

You don't have to re-invent the wheel.

The downside to Bill's idea is you have to do more planning. If you put /var/spool on its own filesystem, you have to figure out how much space it needs and make sure it has enough. You will probably consume more disk space for /var and its subfilesystems under this scenario.

The result of considering this approach however is a system that is even more robust.

LVM concept. A disk can not be split into two logical volumes. The maximum number of logcial volumes a physical disk can be in is one.

SEP

[jp]

Steven, thanks for the long post, exactly what I need to know....want to plan for ease of use down the line. I really want to be able to minimize disruption - only have to shut down eloquence users, rather than everybody when issues like space come up. Once I know how flexible Eloquence is in regards to file location, I can try to plan out how to do this.
Thanks,
jp

[Bill Hassell]

To expand on Steven's comments, /var is the biggest and most dynamic filesystem in HP-UX. It is almost always too small. Think in terms of 1000 to 4000 megs. Now /var is used for many, many different tasks like email, printing, logfiles and in your case, Eloquence. I would not try to move Eloquence's choice for /var--it is the industry standard for Unix and Eloquence may not have any option to configure temp space locations. (note that /tmp is defined as system temporary storage, not applications).

As far as having two disks, please order disk mirroring immediately. This is incredibly cheap insurance for loss of your operating system disk (and in your case, Eloquence's data too). You may want to look at offloading the Eloquence data files to an external set of disks (also mirrored) for best performance.

You'll find that increasing /opt, /usr, /tmp and /var are fairly common tasks for any system administrator, especially while the system is growing. These 4 directories require single user mode to increase since they are always busy. The Advanced JFS product allows you to increase the size without rebooting but get the disk mirroring software first.

As mentioned, you can ask Eloquence support where all the /var files are located and then create a separate lvol just for Eloquence files.