topic Re: MirrorDisk/UX documentation in Operating System - HP-UX

MirrorDisk/UX documentation

Olivier Drouin — Tue, 27 Jan 2004 15:49:31 GMT

'sup

I need to learn how mirrordisk/UX works. Right now I'm reading http://docs.hp.com/hpux/pdf/B2355-90742.pdf which is a great file for recipes on how to do specific things but it doesn't explain the how's ( for mirrordisk ).

In the beginning of the chapter the author states:

###
If you would like to learn more about basic mirroring tasks, it is
suggested that you refer to the book Disk and File Management Tasks on
HP-UX published by Prentice Hall PTR, 1997.
###

which I cant find. Is there any other files/sites that I could read ??

Thanx.
O

Re: MirrorDisk/UX documentation

Sridhar Bhaskarla — Tue, 27 Jan 2004 15:52:52 GMT

Hi,

Look at the following document "Managing Systems and Workgroups: A Guide for HP-UX System Administrators " at docs.hp.com

http://docs.hp.com/hpux/onlinedocs/B2355-90742/B2355-90742.html

Look at "Managing Disks and Filesystems" Chapter. You should get all the information needed.

-Sri

Re: MirrorDisk/UX documentation

Olivier Drouin — Tue, 27 Jan 2004 16:00:45 GMT

hard day @ work, huh?! -_-

Thanks but thats the file I'm talking about in my post...

Re: MirrorDisk/UX documentation

Jeff Schussele — Tue, 27 Jan 2004 16:16:22 GMT

Hi Olivier,

The HP-UX SW Recovery handbook - specifically the LVM chapter - has a good section on Mirror-UX.
Here's the link to the LVM chapter:

http://www1.itrc.hp.com/service/iv/docDisplay.do?docId=prodITRC/DE_SW_UX_swrec_EN_01_E/LVM.pdf

You can get to the entire handbook via the "Navigate Knowledge Trees" link of the ITRC home page.

HTH,
Jeff

Re: MirrorDisk/UX documentation

Jeff Schussele — Tue, 27 Jan 2004 16:25:00 GMT

And it should be noted that no *new* commands are introduced by the install of Mirror-UX, rather certain functionality (lvextend -m X for example) is introduced. So there are probably no manuals, per se, for Mirror-UX exclusively. But *any* good LVM manual will have what you want.

Rgds,
Jeff

Re: MirrorDisk/UX documentation

Mic V. — Tue, 27 Jan 2004 17:35:36 GMT

From amazon.com:

Disk and File Management Tasks on Hp-Ux (Hewlett-Packard Professional Books) by Tom Madell, Thomas Madell (Paperback - January 1997)
Books:
Buy new: $29.40 Used & new from $24.50 Special Order

One thing to remember about MirrorDisk: whatever you do with it, the host (computer) performs the processing. That means if you're mirroring, the process of keeping disks synchronized is being done by your computer and those resources are not available for the regular "work" that the computer is doing. That's one reason that people invest in external disk arrays (EMC, Hitachi, HP) -- they may perform RAIDing for you, thus offloading the resource drain from the host.

HTH,
Mic

Re: MirrorDisk/UX documentation

Sridhar Bhaskarla — Tue, 27 Jan 2004 17:40:41 GMT

yeah.. It's a kind of multi-tasking day.

Jeff got the stuff for you.

Have a good day.

-Sri

Re: MirrorDisk/UX documentation

Jeff Schussele — Tue, 27 Jan 2004 17:44:19 GMT

Hi mic,

That's true to some extent, but remember most of the double-write penalty is offset by the ability to direct reads to 2 different devices - i.e. the next read is always placed on the device with the smallest queue.

But, in my mind, mirrors are about safety & availability. In our shop all our local or non-RAID storage is mirrored so drive failures do not cause us downtime.

You really have to look at Mirror-UX that way - it's not intended for performance - it's for availability. I wouldn't even think about using MC/SG w/o Mirror-UX.

My 2 cents,
Jeff

Re: MirrorDisk/UX documentation

Mic V. — Tue, 27 Jan 2004 17:50:23 GMT

Jeff,

How would you handle a SG cluster with a 300GB database hosted on a Symmetrix/Hitachi/XP (database only active on one node)? MirrorDisk on the host or let the array handle it?

Just trying to understand your perspective. Sorry to be off-topic.

Mic

Re: MirrorDisk/UX documentation

Jeff Schussele — Tue, 27 Jan 2004 17:53:39 GMT

An array RAID5 of course.
Would you want to boot off of it?

Back at ya,
Jeff (Who keeps vg00 safely close to home & mirrored)

Re: MirrorDisk/UX documentation

Mic V. — Tue, 27 Jan 2004 19:17:53 GMT

Of course not, but I didn't mean to suggest same, either. :)

And yes, I keep vg00 "safely close to home and mirrored" too. No offense intended, hope none taken.

Mic

Re: MirrorDisk/UX documentation

Jeff Schussele — Wed, 28 Jan 2004 13:48:15 GMT

Hi mic,

Nope - none taken.
Just returning your serve.
Hope the same holds true for you.

My view is that I don't want a single system w/o Mirror-UX AND OnLine JFS - guess I'm just getting spoiled as mgmnt *always* provides them this way. We only mirror non-RAID disks - i.e. internal or JBOD drives.

Best Rgds,
Jeff

Re: MirrorDisk/UX documentation

Mic V. — Wed, 28 Jan 2004 14:05:51 GMT

No prob, none taken. Yeah, in the "good old days" I had the same -- MirrorDisk, multiple internal drives, and GlancePlus Pak for all systems, plus OnlineJFS for servers difficult to take offline. In recent times, though....no $$$. :( Production systems on old hardware with old disks and no support contracts. And my department isn't even the worst.

ttfn,
Mic