topic Re: Using mirror-ux vs hardware level mirroring in Operating System - HP-UX

Using mirror-ux vs hardware level mirroring

Debbie Beresford — Wed, 15 Mar 2006 12:38:41 GMT

We are currently on an RP5470 system running HP-UX 11.0. Mirroring is done with an I20 - 4si - raid card. We are upgrading to HP-UX 11.23 and have found this raid card is not supported.

We are currently looking at 2 options:

1. Replace the raid card with another type of raid card
2. Use Mirror-UX and mirror at the software level.

Does anyone have any suggestions? Have you found there is a performance hit using software vs hardware mirroring? System performance is not currently a problem for us. Also, we are running Oracle databases if that makes a difference.

I look forward to hearing of any experiences/advice you may have.

Re: Using mirror-ux vs hardware level mirroring

Steven E. Protter — Wed, 15 Mar 2006 12:46:47 GMT

Shalom Debbie,

I think the industry agrees that doing it with hardware is better. Mirror/ux is the best raid software I've ever used, but hardware raid lowers the strain on the system CPU and leaves it for other work.

See Charles Keenan, HP-UX CSE

SEP

Re: Using mirror-ux vs hardware level mirroring

Carlos Roberto Schimidt — Wed, 15 Mar 2006 13:00:11 GMT

Hi,

Hardware mirroring is better, but if you want mirror just your filesystem from vg00, my sugestion is to use mirror-ux.

I dont have perfomance trouble using mirror-ux just for mirror operation system.

But if you want mirror Database for example, my sugestion is for use hardware mirroring.

Schimidt

Re: Using mirror-ux vs hardware level mirroring

Jeff Schussele — Wed, 15 Mar 2006 14:06:58 GMT

Hi Carlos,

In my experience I've found that Mirror-UX imposes a very small penalty due to having to complete two writes...BUT...you can actually gain read performance because the kernel will place the read request on the smallest queue.
And neither is worth a darn if they're using the same controller path. *Both* HW and SW mirroring should *alway* have separate paths to whatever disk device(s) is(are) being used.

My 2 cents,
Jeff

Re: Using mirror-ux vs hardware level mirroring

Jeff Schussele — Wed, 15 Mar 2006 14:50:12 GMT

I should have also added that we hardly ever use mirror+stripe or stripe+mirror on our RAID arrays. We *always* use RAID 5 - it just as robust, faster & a *hell* of a lot cheaper.

Rgds,
Jeff

Re: Using mirror-ux vs hardware level mirroring

Debbie Beresford — Wed, 15 Mar 2006 15:34:14 GMT

Thanks everyone for your input. I will forward this on. Does anyone have any suggestions for controller cards?

Re: Using mirror-ux vs hardware level mirroring

Patrice Le Guyader — Wed, 15 Mar 2006 15:35:44 GMT

hi Debbie,

As all have said, hardware raid is better but mirror UX is a good software. If it can help, we have hundreds of servers, HPUX and SUN. All of them have mirrors for systems disks made with software and there's no problem. And even on High end servers like Superdome or SF25K.
For one application, we've made a mirror between two arrays and this is done with mirrorUX, the only small problem is a high activity of vxfsd daemon, but it's running well for many hundred giga of data.

Hope this help.

Regards
Pat.

Re: Using mirror-ux vs hardware level mirroring

Debbie Beresford — Thu, 16 Mar 2006 06:28:40 GMT

Thanks for your help everyone.

Re: Using mirror-ux vs hardware level mirroring

Debbie Beresford — Thu, 16 Mar 2006 06:30:20 GMT

Looks like we'll go with hardware mirroring. Thanks for your help