Stripping and mirroring not possible with lvcreate -i 4 -I 32

[Craig Warnholtz]

HP-UX 11
I just had a discussion with our HP Rep. I told him that I wanted striping and mirroring with a 32K stripe size. He said we could not get striping AND mirroring when using the command lvcreate -i 4 -i 32. He said that would only get me striping and could not give me mirroring. If I want mirroring and striping we must use lvcreate -D (distributed)!

Is this true? Will lvcreate -D give me what I want?

[Sridhar Bhaskarla · Accepted solution]

Hi,

He is correct. You cannot do both striping and mirroring with LVM. You can use Extent Based Mirrors (-D Y -s g). However, here the stripe size will be equal to your extent size. If you have an extent size of 16MB, then this striping will have very minimum effect.

-Sri

[James R. Ferguson]

Hi:

Yes, true striping and mirroring are not supported with LVM. You must use 'extent-based mirror stripes'. See the man pages for 'lvcreate' for more information.

If you use VxVM, however, you can stripe and mirror.

Regards!

...JRF...

[S.K. Chan]

The man page for lvcreate actually explained it quite clearly.

[Patrick Wallek]

In this case what he told you is true. If you require mirroring, your only option is Distributed Striping (-D option to lvcreate).

This striping will ONLY give you stripes the same size as the PE size your VG was created with.

This also requires that you have your VG set up with PVGs (Physical Volume Groups).

[A. Clay Stephenson]

This is true and even worse I have been less than impressed with VxVM as it (and its associated daemons) adds noticable overhead to the system.

The problem with extent based striping is that the PE's are so large (>= 1MB) that the striping benefits are quite small.

[Rammig Claus]

Hi Craig,

if your disks are on an EMC or XP-Box, you can stripe the disks in the Box and mirror with LVM.

Let the sun shine ...
Claus