Creating a LUN > 2TB

[S.Maxwell]

Hi All,

We have an EVA4000 and I'm looking at how we can present more than 2TB space to the cluster and still keep specific drive letters (Cluster is for SQL Server and we have a S and T Drives for data and logs).

In the not too distant future; we will fill the current 2TB Allocation, so I will need some more.

I dont really want to assign additional LUN's and subsequently more drive letters.

Is it possible via Command View EVA to present more than one VDISK to a LUN and then just present the single LUN ?

Cheers,

Steve
SQL Server DBA

[Denver Osborn]

No, AFAIK this isn't possible with the eva4000. The largest vdisk (lun) you can create is 2TB. You can create multiple vdisks and present them to the host, but each lun will be unique.

Maybe there's a way with the windows disk manager to have the luns appear as a single disk... I'd suggest looking at this from the windows disk manager perspective as the storage array can't do it.

-denver

[IBaltay]

Hi,
its an EVA limitation. The problem of the insufficient number of the drives can be solved by the mountpoints, which are MS supported also for the MSCS.

[Heironimus]

There are some technical challenges to getting that much space in one chunk. The DOS-style MBR partition table that is almost always used on x86 hardware can't define a single partition over 2TB. It's only within the past few years that the SCSI command set was expanded to support block addresses past 2TB (I think that spec was published in late 2004 or 2005), so anything that hasn't implemented that newer spec also can't use/present a LUN over 2TB.

You're going to need more LUNs, it's just a matter of figuring out how you want to deal with them (more drives, mount points, dynamic disk, etc).

[Philip Teale]

Hi Steve

We came across the same problem a while ago, we needed a single drive letter volume on a MSCS clustered host with a capacity of 14TB. In a non-clustered environment you can of course present multiple LUNs to Server 2003 and have the OS concatenate them into one large volume. But in order to do this they need to be converted into dynamic disks, which are unsupported in a Clustered environment. We solved this using Veritas Storage Foundation which allows the use of dynamic disks in a cluster. What I did was to present multiple 2TB LUNs to one node in the cluster and used VSF to make them dynamic and then spanned them all into one large volume. Then I presented the LUNs to the second cluster node and VSF picked them up.

I have to say that it is a bit scary doing this because if one of the LUNs disappears for any reason, then the whole volume is marked as being offline. It is always a hair-raising experience watching the cluster fail over and seeing 7 2TB LUNs moving from one node to the other, and waiting for them all to be available before VSF can bring the volume online. However, we have done this several times and we have yet to have a problem - touch wood!

If you need any more help setting this up, let me know. I would be glad to help.

Cheers

Phil