topic Re: Luns and vgs in Operating System - HP-UX

Luns and vgs

Emilio Brusa_1 — Mon, 05 Jan 2004 19:05:53 GMT

HAppy new year!!

Which is the best size for Luns in va7400 and 7400 I have 4tb in raid 0+1 2tb.
which is the best idea 4 luns of 10 gb for one vg or 2 luns of 20gb for example ??

Many people saids the size dont import.`but i dont know.

Thanks

Re: Luns and vgs

Michael Tully — Mon, 05 Jan 2004 19:08:52 GMT

The best method I would recommend, is to make them small enough so you don't have the potential to waste space, but large enough so it doesn't make it a management headache, so in saying that 8-10Gb LUN's would be my preference.
Happy New Year to you as well!

Re: Luns and vgs

Emilio Brusa_1 — Mon, 05 Jan 2004 19:27:51 GMT

Hi Michael for your quick response.

Â¿how could have potential waste space in large configuration ?

Thanks

Re: Luns and vgs

Michael Tully — Mon, 05 Jan 2004 19:36:36 GMT

If you have the LUN sizes too large, there is potential waste utilising one large LUN for a small volume group requirement. This is helpful when systems are being shared for more than one application. We like to keep seperate our data and application binary volume groups and using a slightly smaller LUN size assists us in making sure that there is no or ver limited waste.

Re: Luns and vgs

Sunil Sharma_1 — Tue, 06 Jan 2004 01:03:18 GMT

Hi,

Size does matter. yes mainly for the sack of administartion. I always prefer to have some Luns of small size and some of large size. generally it depends on requirment of Application. but it always gud to have a combination of Small and big Luns.

very happy new Year

Sunil

Re: Luns and vgs

Elmar P. Kolkman — Tue, 06 Jan 2004 03:41:55 GMT

If you are going to use the luns for vg00, don't make those luns too large if you might use ignite in the future to make recovery tapes.

Sometimes it's better to use not too large luns for the rest of the system too. You can always use LVM to add extra luns to an existing volumegroup if the size is not large enough. If important, you can then even stripe and make sure the data is better distributed inside the disk cabinet.

Re: Luns and vgs

Dave Polshaw — Tue, 06 Jan 2004 07:16:05 GMT

I would go for some small LUNs that can be moved between VGs should the need arise. If, however, you know for certain that a particular VG is going to be larger there is no reason not to create one or two large luns to accomodate that.

Remember (Like I didn't!) to allow for larger luns in your vgs or you will have the headache of recreating them if you want to have a larger lun later.

Cheers

:D

Re: Luns and vgs

Emilio Brusa_1 — Tue, 06 Jan 2004 12:51:07 GMT

Hi everyone!
thanks for yours answer.
I have a question
what smaller is small and what larger is large ?

I think smaller is 5-15 gb
in the middle 20-40 gb
and larger 40-100 gb

its correct ?

thanks