Disconnect the FC SAN before installation or not?

[ruszalai]

If I remember well you had to disconnect the shared SAN storage from

the second node of the ESX cluster before you install ESX on that node

otherwise it reformatted it without a question during installation

Is this still true with ESX 4i or I can install the second node without disconnecting the SAN?

Thanks,

Rudi

[kooltechies]

You are using the Thin installable or the embedded on the chip ESX i ?

Thanks,

Samir

P.S : If you think that the answer is helpful please consider rewarding points.

[ruszalai]

Hi,

It will be ESXi 4 installable.

Thanks,

Rudi

[kooltechies]

I will still advise to disconnect the cables from the second server while installation.

Thanks,

Samir

P.S : If you think that the answer is helpful please consider rewarding points.

[ruszalai]

Do somebody have some factual information about this? Can ESXi 4 installation mess up the attached SAN when installed on the local drives? I know it wouldn't hurt to detach the fiber cables, but the physical servers are a bit far from us and the local IT staff cannot be trusted even with the simple task of unplugging-plugging cables.

[StateMCSM]

I too, am interested in the answer to this question. I don't mean to hijack this thread but I have a question of a similar topic. I have two physical blade servers connected to a SAN via fibre channel. If I create two VMs on each physical server's local datastore for a total of four VMs, can I connect them to the same Data Block on the SAN? I would like to create a 250GB block and mount it on both physical servers as datastore2. From there, I would configure each VM to have a 60GB partition on the datastore. Is this possibe?

[AndreTheGiant]

I always remove the cable before the installation (except in boot from SAN cases).

For most HP server, for example, the first disk is not the local one.

And, for example, if you install ESX 4.0 you cannot choose were put the Console vmdk file (and it can go to a shared storage).

Andre

[mdparker]

Without a shadow of a doubt, I'd unplugg the FC cables to be on the safe side ... or I'd remove the SAN luns from servers via your admin tools. I have not attempted leaving the cables in on ESX4, but I did do that on ESX3 by accident and it formatted some SAN luns. Unless they have made some improvements in that area, I'm sure ESX4 would do the same. Better safe than sorry anyway ....

Mike

[ruszalai]

Thanks for this information. Even if we still don't know if ESX 4 formats the visible LUNs without a question it is a good reason to go through the hassle of disconnecting it from the SAN.

[ruszalai]

Seing the same LUN from both node not a problem, that's the normal for an ESX farm.

Adding a disk (which will be a vmdk file on the shared LUN) to one virtual machine which is running on one node is OK and normal too.

Adding the same VMDK as an existing disk to another vitual machine can be tricky. Actually this is exacly the configuration what you create when you try to make a MCSC cluster. Here is a step-by-step description of the whole process:

http://exchangeexchange.com/blogs/bkeane/archive/2007/07/30/mscs-clustering-in-vmware.aspx

[RParker · Accepted solution]

I too, am interested in the answer to this question.

This was a problem with ESX 3.0, because if you weren't paying attention all it was say is the space size, and not identifcation aout WHICH space it was referring, so to avoid this you disconnect so you wouldn't format a LUN in use.

Later it became easier to identify the local storage from a LUN, but still if you weren't paying attention you could over write your LUN. NOW with ESX 4.0 it defaults to local AND it clearly identifies not only the LUN or SPACE but the device, in our case it shows Dell Perc with 600GB and Netapp LUN 5 with 750 GB something like that, so it's easier to see.

So it is less of a problem to tell which space you install ESX on, so I say leave the cables connected, it's fine. It was always about experience and knowledge about your storage, if you KNOW your space it's not a problem, if you have a SAN admin and an ESX admin and they aren't the same person, it's best to just have the ESX admin disconnect the cables to avoid making a catastrophic mistake.

[RParker]

Thanks for this information. Even if we still don't know if ESX 4 formats the visible LUNs without a question it is a good reason to go through the hassle of disconnecting it from the SAN.

That's great EXCEPT for those of us that install remotely OR install via the DRAC, this is a pain to do this at the console if you don't have to BE at the console to install.....

[ruszalai]

Thanks, that's all the info I really needed!

Rudi

[mcowger]

If you use PXE you can force it to only use local drives found via a particular driver (thats what we do).

--Matt

VCP, vExpert, Unix Geek