topic Re: Mirror and striping. in Operating System - HP-UX

Mirror and striping.

Pippo_9 — Tue, 10 Feb 2004 09:48:45 GMT

Hi folks.

Does HP-UX support mirror and striping at the same time?

Is it possible to do that?

Thanks

Juan

Re: Mirror and striping.

Patrick Wallek — Tue, 10 Feb 2004 09:51:02 GMT

No, you can't have true LVM Striping and mirroring with LVM (combining -i -I and -m options to lvcreate).

What you can have is Distributed striping along with mirroring. With distributed striping your "stripe" size is the same size as the PE size you set up the VG with. With distributed striping you use the '-D y' option with lvcreate. You must also set up Physical Volume Groups (PVG) the Distributed striping "stripes" across all disks in the PVG. You would then set up your mirror with the PVG-strict option (-m 1 -s g with lvcreate).

Re: Mirror and striping.

Patrick Wallek — Tue, 10 Feb 2004 09:51:41 GMT

I forgot to add -- Have a look at the lvcreate man page for more information on the Distributed striping options.

Re: Mirror and striping.

Pete Randall — Tue, 10 Feb 2004 09:51:54 GMT

Juan,

See the man page for "lvcreate", in particular the -i stripes and -m mirror_copies options.

Pete

Re: Mirror and striping.

Pete Randall — Tue, 10 Feb 2004 09:54:48 GMT

Juan,

Actually, for a better explanation, see Patrick's response(s) above!

Pete

Re: Mirror and striping.

Lorenzo Facello — Tue, 10 Feb 2004 09:55:02 GMT

No, you can't... but what you are going to do?

Re: Mirror and striping.

Pippo_9 — Tue, 10 Feb 2004 09:55:07 GMT

Guys,

I know that 11.00 supports "pseudo-striping".
I wonder if it is the same on 11i

Paco

Re: Mirror and striping.

Helen French — Tue, 10 Feb 2004 09:55:55 GMT

This question has been answered so many times in the forums. Do a search on ITRC and you will get lot of good answers.

To answer your question, you cannot have both mirroring and striping at the same time. But if you want to use Distributed striping (with option -D y), you can use it with mirroring.

Re: Mirror and striping.

Helen French — Tue, 10 Feb 2004 09:59:03 GMT

To the last question: Yes, HP-UX 11.11 version supports pseudo striping.

# man lvcreate (for details)

Re: Mirror and striping.

Sridhar Bhaskarla — Tue, 10 Feb 2004 10:00:36 GMT

HI Juan,

As already mentioned, it's not possible with LVM. You can do extent level striping/mirroring but that doesn't qualify as striping and mirroring. Here the stripe size is equal to your extent size which in most cases is 4MB. A stripe size of that big is not useful. Ofcourse it may be slightly better than non-striped LVs.

You will need to use VxVM (Veritas Volume Manager) which is a completely different realm.

-Sri

Re: Mirror and striping.

Patrick Wallek — Tue, 10 Feb 2004 10:05:53 GMT

The "pseudo-striping", aka Distributed striping, was first made available in 10.20 with a patch, 11.0 and yes it is available in 11.11 as well.

I have used it in the past, and I am actually currently using it on some FC10s on a 10.20 box. The Distributed striping may not be the ideal setup for "striping" and mirroring but it does work. I personally think it's better than nothing.

Re: Mirror and striping.

Pippo_9 — Tue, 10 Feb 2004 10:12:04 GMT

Summing up,

you can't have regular striping with mirror at the same time on 11i (the version which I am interested in), you can only have "pseudo" striping.

Correct??

Juan Paco Morientes

Re: Mirror and striping.

Patrick Wallek — Tue, 10 Feb 2004 10:23:54 GMT

You are correct, yes!

Re: Mirror and striping.

Patrick Wallek — Tue, 10 Feb 2004 10:25:43 GMT

Actually, if you are talking strictly LVM then yes, you are correct.

If you want to buy or upgrade to the full version of Veritas Volume Manager that product WILL allow a true RAID 10 (striping/mirroring) volume.