Mirror and striping.

[Pippo_9]

Hi folks.

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

Is it possible to do that?

Thanks

Juan

[Patrick Wallek · Accepted solution]

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).

[Patrick Wallek]

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

[Pete Randall]

Juan,

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


Pete

[Pete Randall]

Juan,

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


Pete

[Lorenzo Facello]

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

[Pippo_9]

Guys,

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

Paco

[Helen French]

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.

[Helen French]

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

# man lvcreate (for details)

[Sridhar Bhaskarla]

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

[Patrick Wallek]

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.

[Pippo_9]

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

[Patrick Wallek]

You are correct, yes!

[Patrick Wallek]

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.