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best way to utilize 4x36GB internal disks -- ??

Kristopher March
Regular Advisor

best way to utilize 4x36GB internal disks -- ??

We may be purchasing a new rp7410 with 4 internal disks. The server will be connected to a DMX 1000 with plenty of additional disk space.

I'm trying to plan for the best use of these disks. A couple thoughts I have is to use one disk for swap, another for vgalt.

Or I could possibly mirror two disks, utilize one for swap. Mirror/UX is necessary to do this correct?

How do you all configure/use them?
"This ain't no burger flippin job!"
13 REPLIES
Patrick Wallek
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

I would use two of them. 1 as your primary boot disk and the other as the mirror. Yes you need MirrorDisk/UX for this. The other 2 you could use for whatever you need. I wouldn't necessarily put production data on them though.

If you don't use them, you could always just send them to me. I'll find a use for them. ;)
Jeff Schussele
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Hi Kristopher,

I'm assuming you intend to have just a single nPar (Hard partition) on this 7410 - correct?
If so, then use 2 disks for a vg00 mirror pair. YES, you'll need Mirror-UX to do this.
Then you could use the other two as a mirror pair for a secondary VG, that could & probably should contain a secondary swap device if you need that much swap.

IF you're going to have two nPars on this systems, then you'd need all 4 disks to have mirrored vg00 pairs for *both* partitions.

My 2 cents,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
Robert-Jan Goossens
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Hi,

If you have some extra money I would go for the second option. Below you can find more info about mirror software.

http://www.software.hp.com/portal/swdepot/displayProductInfo.do?productNumber=B2491BA

Regards,
Robert-Jan
Mark Grant
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Mirror/ux is definately needed for mirroring though why HP don't provide this enterprise requirement for free is beyond me.

I personally would get mirror/UX. I would have vg00 include all of the disks. I would then put boot, root and swap on the first disk and mirror them onto the second disk. I would then make that bootable too.

The third disk would be for vg00 and it would be mirrored to the fourth.




Never preceed any demonstration with anything more predictive than "watch this"
Paula J Frazer-Campbell
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Hi

One for OS and second for mirror disk - mirrordisk is required for this.

Use the other two for whatever - I would hold them for sysadmin use if you can get away with it.

Paula
If you can spell SysAdmin then you is one - anon
Jeff Schussele
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Hi Mark,

Well - technically - IF you buy Mission Critical OE, *then* Mirror-UX is "free", as well as MC/SG, OnLine JFS, Glance, etc....

But we all know that it's not entirely free, just included in the price.

Rgds,
Jeff
PERSEVERANCE -- Remember, whatever does not kill you only makes you stronger!
Mark Grant
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

I would like to add that, of course, boot,root and swap are also in vg00!
Never preceed any demonstration with anything more predictive than "watch this"
Mark Grant
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

point taken Jeff :)
Never preceed any demonstration with anything more predictive than "watch this"
Leif Halvarsson_2
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Hi,

I dont think there is much idea to use a dedicated swap disk unless your system is very short of memory. If there is enough memory there should be no swapping at all (and the disk is not used). Configuring a ordinary swap volume in the root volume group should be enough.
Sridhar Bhaskarla
Honored Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Hi,

Two disks will go into vg00 with each mirror to other. You will have plenty of space in even those disks. Since you are going to get additional disk space from DMX, configure one disk as dump device by putting it in a seperate VG.

Leave the other disk as it is but perform a regular 'dd' from your root disk to it. Use it as a backout plan for any changes you make to the system. For ex., do a 'dd' of your primary disk to it before you apply your patch bundles. If something doesn't work, then replace the primary disk with this disk for a quick backout.

-Sri
You may be disappointed if you fail, but you are doomed if you don't try
A. Clay Stephenson
Acclaimed Contributor

Re: best way to utilize 4x36GB internal disks -- ??

If this were me, I would purchase MirrorUX and OnlineJFS (I consider those "must haves" for any serious HP-UX box)) and use all four disks as vg00.

Make sure that each LVOL is mirrored on physical drives connected to a separate bus.
The main reason for using all four (as opposed to only two) is to allow you to get the busiest filesystems off the boot disk. That means that /var should be placed on the non-boot disks.

On modern boxes, if you have to worry about swap layout then you almost certainly haven't purchased enough memory. My normal way to do this, is to create a small primary swap area (mirrored) of 512-1024MB, enable pseudoswap, and then monitor swap usage.
With swapmem_on=1, you need an additional 25% of total memory configured as swap to allow full virtual address space usage. Assuming that you have enough swap configured to allow access to the entire virtual address space and if the pageout rate is very low then you have enough swap. The old rules about 2x-3x swapspace (which is 4x-6x with mirroring) very seldom apply.

The main advantage of mirroring on separate buses like this is that you can replace disks "on the fly" and never have to bring the system down.
If it ain't broke, I can fix that.
Kristopher March
Regular Advisor

Re: best way to utilize 4x36GB internal disks -- ??

Great responses.

I will save this message and consider all your suggestions in the future.

Thanks, everyone.
"This ain't no burger flippin job!"
A. Clay Stephenson
Acclaimed Contributor

Re: best way to utilize 4x36GB internal disks -- ??

Let me give you a Plan B. Use just two of these disks (again, on separate buses). This doesn't allow you to put /var on a separate disk BUT it does allow you to do something else. Create a 'lifeboat' disk. During quiet periods (weekends are good) have a cron job that does a raw dd copy of your boot disk to your lifeboat. This protects you from two things that mirrors do not: 1) Really, really bad patches 2) Your own stupidity. If you ever need it, all you have to do is pop out your primary boot drive and plug the 'lifeboot' into the primary's slot. You then boot normally. Because the copy was done on mounted filesystem, an fsck will be automatically done but I've never had one of these to fail. You can have a box back up in a fraction of the time it takes to Ignite a box. You might consider using the remaining disk as a dump device -- and dump should never be mirrored. Note that dump devices should really have nothing to do with swap devices. Because it's so easy to add additional swap, it's really not worth worrying over when you first configure your box.
If it ain't broke, I can fix that.