online jfs + size of root /

[Dave La Mar]

We are a new shop to HP-UX with
2 N Class and one L Class.
We have been told conflicting
things concerning online jfs.
Our root / directory is 155648
on both N Class machines and
147456 on our L Class machine.
I assume these to be defaults as
no one has adjusted them since
installation.
Questions:
1. Since root / must be
contiguous space is it correct
to assume online jfs will not
help in expanding this?
2. The L Class is used for
tape backups only of business
copy volumes. Would it be unwise
to install online jfs from a
financial view?
3. What is the norm for the
size of root /?
I realize this will very according
to shop but am looking for a mean
value.

Note: My apologies for the empty
postin yesterday. Seems any submit I
attempted failed.
Thanks for any and all input.
dl

[Bill McNAMARA_1 · Accepted solution]

1. Since root / must be
contiguous space is it correct to assume online jfs will not help in expanding this?

> I tested this today, and
> ran into trouble..
> but I was doing /stand (oops!)..
> could recover though
> lvchange will change strictness
>
2. The L Class is used for
tape backups only of business
copy volumes. Would it be unwise
to install online jfs from a
financial view?
> I dunno, depends if you think
> that increasing the vg00
> filesystems offline
> (30 mins work max) will
> mean the licence fee in
> lost revenue..
> probably not..


3. What is the norm for the
size of root /?
I realize this will very according
to shop but am looking for a mean
value.
>
> 143360 55195 82669 40% /
on a 18G disk A500.

I don't need much, for my case, /opt/ and /var are 50% of the disk..

Later,
Bill

[A. Clay Stephenson]

Hi Dave:

1) You are correct, / must be contiguous so OnlineJFS is no help. The supported methed is to do a make_tape_recovery and Ignite to restore your system.

2) My suggestion is that every box needs OnlineJFS; you get so many more features other than extending filesystems. I suspect that the expense of the product is more than offset by the decrease in admin time and downtime. You also get snapshot mounts which can let you rethink how you approach backups and mount options that let you have essentially raw/io while using cooked files.

3) While it is true that / should essentially never grow, I alway size it and stand bigger than necessary so that OS upgrades are possible. A few of those upgrades (rather than cold installs) actually work well now. I've done one in a ServiceGuard environment and it went very smoothly. It would not have had I used the default sizes for /. I've would suggest about 160-200 MB for / and about 100-128MB for /stand. It's overkill but you should then be able to upgrade no matter what. If you have OnlineJFS, you can expand the other filesystems on as as needed basis and there is no need to size them large. One other point, I typically only configure about 256MB of primary swap and the other swap is either on another volume group or filesystem swap (if I'm really not going to swap).

Regards, Clay

[James R. Ferguson]

Hi Dave:

First, the root ("/") directory shouldn't be the respository of much of anything. Somewhere around 140MB size is more than adequate. "Off" of root you can define and mount other directories.

Second, in my opinion, Online JFS is a *must* on any server. Not only do I want to be able to expand a filesytem without having to unmount it, but I also want the performance benefits I can achieve with some of the JFS mount options that are only available with Online JFS -- noteably 'mincache=direct,con
vosync=direct' for database filesystems.

Lastly, yes, the root filesystem must be contiguous. *BUT* with Online JFS it is possible to extend the root filesytem. The procedure is described in Technical Knowledge Base docuement #KBRC00006582.

However, as indicated, the root filesystem doesn't need to be very large. The appropriate thing to do is create mountpoints "off" of it to hold data.

Regards!

...JRF...

[Dave La Mar]

Thanks for all the input.
I guess I will bite the bullet and order online jfs for the L Class.
dl

[Geoff Wild]

Dave,

I guess my question is - why would you want to increase the size of the root file system?

You really shouldn't need more then 140MB.

Here's what we do for a "standard" HP build"

Preamble: VG00 - VG09 are internal disks and VG10 and up are on EMC(or other external disk storage).

VG00
The root volume group VG00 should be mirrored and only contain OS files.
Primary swap should be 1 x memory
/ - 140MB (HP Default)
/usr - 1 GB
/var - 1GB
/tmp - 512MB
/stand - 128MB
/var/adm/crash - 1 x memory + 512MB
/opt - 1GB
/home - 512MB with quotas (32MB soft, 64MB hard)


Note: /var/tmp should be a symbolic link to /tmp. /tmp should be 1777 (sticky bit).



VG01
/app - 512MB
/usr/local - 512MB
/app/admin - 512MB


VG02
File system swap


VG03
Applications


VG04-VG09
Reserved




VG10 - VG29
Log volumes (redo, archive, etc)


VG30 - VG256
Data volumes

[John Bolene]

Online jfs is well worth the money on any machine.

I use 1.2G for /root on my dedicated DNS servers, the only other lvols are /stand, and /var.

On the other servers /root is 500 meg. All the other big dirs are broken out.

[Krishna Prasad]

This how root vg00 is setup for us.
We always use online JFS and Mirror/UX

/ 140 MG vxfs
/stand 85 MG hfs
/var 1 GB vxfs
/usr 2.5 GB vxfs
/tmp 155 MG vxfs
/opt 625 MG vxfs
/home 20 MG vxfs

and some swap space

[Deshpande Prashant]

Hi
Online jfs is worth the money on machine.
Don't you have other volume groups/file systems other than vg00. Managing them will be much easier with Online JFS.

Thanks.
Prashant.