RDM Size

Hello all...looking for options here is all...something I may be overlooking.
I have a VM with Volumes associated with it; as far as virtual infrastructure goes, those Volumes are RDMs from a fibre channel EMC CX4 SAN. I want to add another RDM to the VM, but the problem is the LUN I want to map to (RDM) is 2.6TB. I didn't think RDM'd volumes mattered necessarily as far as the storage config max of 2TB goes, but it does it seems. Is there a way to get this to work with the size I'm wanting to have? My only thought for getting this to work (have a single volume on the VM) is to destroy the LUN I have now (at the moment, there's no data on the LUN), create 2 LUNs of 1.3TB, add them to the VM, and make them dynamic volumes so as to span them into 1 volume. Does anyone have any ideas how to overcome doing it like this?...in other words I want to be able to add 1 RDM (if possible) and be done with it.
I have ESX4 and the above mentioned SAN.

Thanks! :)
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coolsport00Asked:
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Paul SolovyovskyConnect With a Mentor Senior IT AdvisorCommented:
The max. volume size for a RDM is 2TB.  The only way around it multiple RDMs or using the MS iSCSI client from the guest OS to connect to an iSCSI LUN as part of the OS
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bbnp2006Commented:
Since this >2TB storage will only be used by a single VM, have you thought of split the large LUN to 2 smaller LUNs as you described above and extend one to the other one to create a larger volume. Mind you that there are pros and cons of doing this. Make sure you do  your home work.
Just food for thoughts.
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coolsport00Author Commented:
The thought came to mind, but not sure how to do an 'extent' as I've never done it before. If you have a doc/ref handy, that would be great; otherwise, I'll research it.

Thanks both.

~coolsport00
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bbnp2006Commented:
The pros of this solution is that you can have a single volume presented to your ESX host with larger than 2TB size, i believe you can have up to 32 extents if my memory serves me right :) but, the downfall of this solutions is not recommended if you have large number of VMs accessing this volumes because if you have scsi locks on your first LUN, all your extents will also be locked for any access. That's why this might be ok since only one VM is accessing this volume in your case.
Good luck mate!
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coolsport00Author Commented:
Yes, 1 and only 1 VM will ever be accessing this LUN/volume, so if the con is with other VMs potentially needing access to the LUN, that will never be, so seems like no issue there. Any good documentation on creating extents "bb.."?

Thx.

~coolsport00
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bbnp2006Commented:
Here's a screenshot of step by step config:
Extend VMFS Datastore in VMware vShpere
http://blog.wilmsenit.nl/?p=630

Hope it helps coolsport00
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coolsport00Author Commented:
Hmm...that references a datastore, which is not what I'm wanting. I need to make this LUN mapped to my VM via RDM. I want to keep my data on my SAN, not a part of a datastore within my vSphere infrastructure. So, I assume extents are out of the question then? :)

~c
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bbnp2006Connect With a Mentor Commented:
Hmmmm.... I see what u mean mate. Sorry for the misleading. Let me do some testing and see if it is possible. I have a feeling it's not possible with rdm since it is only a vmdk file with a pointer to the underlying LUN.
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ryder0707Connect With a Mentor Commented:
I think you already answer your question in your "Question" :)
I dont think there is a workaround to overcome 2TB limit as its not only for vmfs but also for rdm
So i think spanning in the guest OS, is your best solution
Cheers!
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coolsport00Author Commented:
Hey "ryder"...good to see you back on here! :)

Yeah...thought so as I haven't found anything else stating otherwise.

~coolsport00
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coolsport00Author Commented:
Thanks for the replies all. I'm gonna do this as I stated in my orig post.
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bbnp2006Commented:
yeah, i did some testing in the lab, and no luck :( can't find anything out there that can help do this at this point, hopefully maybe the next release? :)
Good luck coolsport00!
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ryder0707Commented:
hey mr cool...nice to see you are still busy collecting points :p
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coolsport00Author Commented:
Tryin to anyway - still learning lots from "paul..", "arun", "bb.." there above, and "jakethecatuk", as well as others. :)
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Paul SolovyovskySenior IT AdvisorCommented:
If you have iSCSI capability to your SAN you can setup MS iSCSI initiator and have a GPT volume attached up to 12TB
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coolsport00Author Commented:
I don't...just FC...thx "paul.." :)

Hey...are any of you going to VMworld here in the states? You are in the states already, aren't you "paul.."?
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bbnp2006Commented:
I just moved to London UK from Canada, so maybe gonna try VMWorld Europe Copenhagen this year in Oct :) Anyone might be there?
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coolsport00Author Commented:
Ha..gosh, I wish! I don't think my Director will let me go to Europe for VMworld tho! :P
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Paul SolovyovskySenior IT AdvisorCommented:
I'm in the US but I have a lot of projects coming up and being a consultant they don't pay me for not being onsite.  Just spent a week in Netapp NCDA training.

It's usually in Vegas, I try to make it at least once a year, if I can schedule during vmorld I'll see if I can go depending on schedule
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ryder0707Commented:
I really wish I could go too but the cost to travel to US is too expensive, dont think my comp will send me there since I'm supporting Ausie clients :(
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coolsport00Author Commented:
I actually haven't been yet.. I've gone to other conferences, but think I'll be able to go this year. I wish it was in Vegas this year. It's in San Fran...which isn't bad, but would rather it be in Vegas. Well..maybe someday we can all meet up at some conference and shoot the technological breeze :)
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bbnp2006Commented:
lol... gotta love Vegas!!! according to the previous location trend, they should go back to Vegas next year. Would be super awesome to meet up at a future vmworld though lol...
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