vg00 on HP-UX

[Philip Chase]

Question? Are the multiple filesystems that make up vg00 in HP-UX necessary or legacy.
I notice that the root in linux is huge and holds everything from root devices to applications, and I started to wonder are we forcing unecessary head movement by specifing locations for the multiple filesystems in the root VG.
Note. I hate doing anything for legacy sake.

[Jeff Schussele]

Hi Phillip,

Well the only "mandatory" LVs are lvol1 (/stand), lvol2 (primary swap) & lvol3 (/).
Although it's highly recommended that /usr, /opt & /var (to a lesser extent) be in vg00 as well. Because if for any reason they aren't available at boot time - it's not coming up.

And IMHO having a "huge" / is stupid, dangerous & frankly downright lazy.

My 2 cents,
Jeff

[Kent Ostby]

The problem with going with a single lvol (or in the minimal case of hp-ux -- three lvols) is that if you have a problem on the filesystem holding /var and need to reload /var then you suddenly need to reinstall your system.

Or if you fill /var or fill /opt, you have filled up root and everything will stop.

By partiioning the operating sytem file system, you add flexibility and stability to your machine.

[Philip Chase]

The purpose of the question is not to reduce workload, it is to try to boost performance.
I am talking about having /var, /tmp and /opt all in the / filesystem. This is an attempt to eliminate forced data fragmentation, caused by filesystems.

[DCE]

Philip,

as others stated, the different mount points are by design for the reasons stated.

VG00 is not meant to be a data or application VG, and as such, the performance tuning you are talking about does not have any measurable effect on the system performance. It also eliminates any disk contention between the OS and applications.

Keeping your data and applications out of vg00 also allows for a cleaner Ignite image for recovery purposes.

All of your applications should be on separate mount points in a different vg than vg00. you can have the application mount points mounted on a vg00 mount (i.e. oracle is installed on a lvol in vg01 that is mounted an a vg00 directory /oracle)

[A. Clay Stephenson]

Dang. That's why my HP-UX boxes run so slow. Why didn't I think of putting everything in / and declaring victory. And defrag just has not been the same since Win98, I mean it was fun to watch but that thing that comes with WinXP is like watching paint dry --- oops, wrong OS. Defrag under HP-UX is just text and even worse to watch.

It's very difficult to measure any significant improvements from defragging vxfs filesystem because they are extent-based. There are some cases that show improvement but generally the improvement is extremely difficult to measure much less perceive.

You can actually reduce HP-UX to just 2 LVOL's if you like, / and primary swap but root must be a hfs filesystem so that would be the logical goal for which to strive. Of course, the performance of hfs is worse than vxfs but we're going for simplicity.

The conventional divisions into separate filesystems for HP-UX is logical and if performance is your goal then it's quite easy to actually separate each filesystem into separate disk(s). The main advantage is future maintenance. The idea under HP-UX is that vg00 should be lean and mean and confined to only the OS. That is what Ignite expects. When / is a separate filesystem and you see it growing, something is wrong because once the system has been in use for a short while, / should be all but static; if the kitchen sink were thrown it, / would grow continuously and you wouldn't know it that were good or bad.

It's very difficult to compare the layout of Linux to that of HP-UX. In many cases, Linux boxes contain only 1 or 2 disks while HP-UX boxes might be attached to hundreds of disks (of course there are cases in which exactly the opposite is true) but how one lays out a box with few disks is different from how one lays out a box with many disks.

Perhaps the most compelling reason to choose the conventional vg00 layout is that its much easier for another admin to work in a more or less standard environment rather than one in which the layout differs radically from the norm. vg00 should be used for the OS and standard appllications (ie those that are swinstalled); everything else should go in other VG's.