First five disks

Question

I am planning to use the space available on the first five disks of our Clariion CX300. The use will be low I/O. My question is can I use all the available space to me or do I need to leave space for flare upgrades etc?

Dulls · Answer

Hi,You can use that available space on first five disks. For FLARE upgrades there is already space allocated for it and its called Private Space and PSM LUN.The FLARE database drives reside on drives 0,1 and 2 and occupy roughly 28 MB each. The FLARE database drives are triple mirrored as well as the External database drives associated with FLARE (~35 MB each).Start of user space @ 6.3GB (Drives 0-4)Start of user space @ 32.43MB (Drives5- max)Message was edited by: Abdullah Khan

Allen Ward · Answer

I have to disagree with you here Abdullah, but I think it may just be a matter of the way the question was posed.

If the intention is to ensure readiness for future FLARE upgrades, you should NOT use all the available space on the first five drives. FLARE upgrades sometimes require some additional space and if you have filled the first five drives you will have to migrate something off to allow for the upgrade.

If you do not want to allow for future FLARE upgrades, you can safely use the entire capacity of the drives (preferably with low I/O host traffic as you already stipulated). Just be aware that you might have to migrate LUNs later in order to complete a future FLARE upgrade.

RRR · Answer

That's what I thought too ! If upgrading from Flare 19 to Flare 24, you need extra free space on these first 5 disks.

So far I've only encountered this on one CX with no customer lun's on the first 5 disks, so upgrading was easy, since nothing needed to be moved, but my CE asked us about it, so I was triggered and remember that we needed some extra space for the upgrade, leaving us with a little less available free space in that raid group.

ljacobsen1 · Answer

The other thing to be aware of is if you put heavy i/o luns on the first five drives it will drastically slow your Navisphere GUI down. I know you said that you weren't going to put heavy i/o luns on the first five drives, but just as an fyi it could slow your Navisphere GUI down.

DGM3 · Answer

If the intention is to ensure readiness for future
FLARE upgrades, you should NOT use all the available
space on the first five drives. FLARE upgrades
sometimes require some additional space and if you
have filled the first five drives you will have to
migrate something off to allow for the upgrade.

A clarification - just upgrading Flare software (e.g. going from R16 to R19 on a CX600, or going from R19 to R24 on a CX700) does not require more reserved space on the first 5 drives. It is a platform _conversion_ (e.g. turning a CX700 into a CX3-80) that can sometimes require additional reserved space.

If you do not want to allow for future FLARE
upgrades, you can safely use the entire capacity of
the drives (preferably with low I/O host traffic as
you already stipulated). Just be aware that you might
have to migrate LUNs later in order to complete a
future FLARE upgrade.

The "CLARiiON Best Practices for Fibre Channel Storage" whitepaper on Powerlink (search by title) contains a section on "Vault and PSM effects" that is also helpful.

Regards,
DGM

CLARiiON

First five disks

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