Creating VMFS datastore, will only let me use 900 GB of a 5 TB LUN

[mcrampton]

Hi, wondering if anyone can tell me what I'm doing wrong here. We have a Dell MD3000i configured and running with iSCSI. We started with 1 RAID 10 set with 4 1TB drives and 1 hot spare. Recently we added 10 more 1 TB drives, filling up the array. I have created a RAID 5 set from these 10 drives. I've carved out 6 x 500 GB LUN's and added them to my cluster, no problems. I want to use the remaining ~4.8 TB as one big datastore temporarily for some data migrations. My host can "see" the 4.88 TB of space in the storage adaptors menu. However, when I add storage and attempt to create a new VMFS datastore, it will only allocate 903 GB of the 4.8 TB of space. I'm sure this is my fault in some way or another. I've attached a couple of relevant screenshots to illustrate, can anyone point me in the right direction? Thanks.

[mcowger · Accepted solution]

There is a 2TB lun size limit. You are seeing the overflow of 4TB.

Reduce your LUN size below 2TB.

--Matt

VCP, vExpert, Unix Geek

[mcrampton]

Thanks for the quick reply. What's the deal with the storage maximum of 64TB minus 64k listed on this page then? http://www.vmware.com/pdf/vsphere4/r40/vsp_40_config_max.pdf

[mcowger]

Thats for the VMFS itself - you can combine multiple sub-2TB luns to create a larger VMFS.

That being said, thats generally a bad idea. Unless you have really good knowledge of what you are doing and/or an uncommon use model, doing more than about 15-20 VMs/datastore or 500GB per Datastore is probably a mistake.

--Matt

VCP, vExpert, Unix Geek

[mcrampton]

Ok, thanks for your help. I'll manage with 3 datastores instead of one for now. It's just temporary then they'll all be destroyed and recreated as 500GB LUNs anyway.