Expand LUN more than 2TB ?

Depends on the FLARE release you're running. According to doc ID emc111629, the max lun size prior to FLARE 19 was 2TB minus one sector. With FLARE 19 & newer, the maximum stand-alone LUN size is one that uses all of the space in a 16-disk RAID group. MetaLUNS let you concat or stripe data across multiple stand-alone LUNs. The number of LUNs you can add to a Meta depends on the hardware you're running (i.e. CX3-80 can have more components in a Meta than a CX3-20).

So....that being said you have a couple of options. (DISCLAIMER - My CX3-80 runs FLARE 24 so that's what I'm basing this on.)

MetaLUN
-) You can concatenate additional space onto the old LUN and expand using diskpart on the host (may not be good for performance depending on environment, requires no restriping of data so capacity is avail immediately)
-) You can restripe data onto an additional LUN and then expand using diskpart on the host (good for performance, must restripe data so capacity not available until restripe completes, restripe can degrade performance of other LUNs on those RAID groups).

There are some additional requirements for the above scenarios.

Grow your RAID group
-) Disks can be added to a RAID group up to the max of 16 disks. I don't know what the impact on performance is here. Based on my array, it restripes the data so the same caveats for restriping above should apply here as well.

As always, your environment and what you're trying to accomplish have more to do with how you approach this than anything. What's good for one application may not be good for another (i.e. file serving vs. SQL).

I'm fairly new to the EMC storage world (been on HDS for a loooong time), so I'm sure the regulars here will have quite a bit to add.

Cheers,
J-

Also...There's a good discussion of striping vs. concatenating immediately below this thread.

J-

Ok,

If you can create a LUN of 2TB and you have an other LUN.

You can Create a METALUN then. The problem is: how can Windows recognize more than 2TB of disk space ?

Does it make sense ?

Cheers

have to convert to GPT partition.

http://www.microsoft.com/whdc/device/storage/LUN_SP1.mspx

Keep in mind that GPT is only available in 64-Bit 2003 and GPT volumes can not be your boot partition and they can not be used as a Cluster Resource.

You do not have to convert to a GPT volume (which requires reformatting the volumet). If the LUN you want to expand to more than 2TB is not in a Microsoft Cluster Services cluster then you can convert the disk to a dynamic disk. Dynamic disks do not store the partition information in the table as the MBR basic volumes do, which allows dynamic disks to exceed the 2TB limit of MBR volumes. Dynamic disk volumes can be as large as the maximum volume size supported by NTFS for the allocation unit size used.

This is all from the "How NTFS Works" article on TechNet:
http://technet2.microsoft.com/windowsserver/en/library/8cc5891d-bf8e-4164-862d-dac5418c59481033.mspx?mfr=true

The default allocation unit of 4KB on a dynamic NTFS volume will allow you to create a volume of about 16TB.

Once you have expanded the LUN as JMERY discussed, then you can expand the LUN in Windows using the diskpart extend command. It is non-disruptive and quick.

Does that answer your question?

Aran

Dynamox,
I saw the section that you are referring to and I thought the same thing when I first read that. But rereading the "How NTFS Works" document, my understanding is that you can assign a LUN greater than 2TB to Windows Server 2003 that is converted to a dynamic disk and will be able to create a partition greater than 2TB.

I am testing this now with some spare ATA drives we have at our BCP site. I will have the definitive answer once the LUN is bound.

Aran

if i am reading this correctly, you are limited to 2T for single disk, only it allows you to stripe/span multiple of those to get to those huge capacities, man ..i would hate to do a restore on one of those guys . I prefer not to use any type of software striping/spanning ..that's why i paid big $$$$ for my array to do that for me ..IMHO.

http://207.46.196.114/windowsserver/en/library/b51311b3-ec61-402e-96cd-986c89ef40eb1033.mspx?mfr=true

awesome.. that will be great to know.

cool ..thanks for taking the time to test this, hopefully Longhorn will take care of these limitations.

Dynamox,
I tried it this morning, and you had read the article right, the limit is 2TB per physical disk or LUN (the OS perspective on what a disk is) for MBR and Dynamic disks. We could convert the disk to a GPT, but as Collier pointed out we need 64bit OS for that, and I am running 32bit out at our BCP site.

We can create dynamic volumes of more than 2TB but, as you said, that involves assigning multiple 2TB LUNs to the server and using Disk Management to create one huge volume using those multiple LUNs. Something I wouldn't recommend.

So it looks like we are stuck with the limits of 32bit Windows.... until Longhorn?

So, Mourad, if you are still following this, you are stuck with the 2TB limit if you are running 32bit Windows. But if you are running 64bit, converting to GPT does require deleting partitions first.

Aran

Excuse my jumping in here, but 32 Bit Windows 2003 with SP2 can handle GPT's up to 256TB (data partitions only). Theres also a hotfix that allows Windows cluster to work with them, too.

We're looking at some of the some issues (expanding a 1.4TB "drive" to 3TB)

Mike O.