TheTechie
Contributor
Contributor

Overcome 2TB LUN limit for SQL database

I'm trying to setup and SQL server (will be used in SQL cluster) using ESXi 3.5 and a HP SAN to host a 2.5 TB SQL database on a RDM drive. I just discovered the 2TB limit for iSCSI which prevents me from connecting ESXi to a LUN that is over 2 TB.

Is there any way I can get around the size limit? I think VMFS would allow us to use multiple smaller LUNs but this doesn't seem to be available for RDM. Would our only option be to use VMFS with extends? Would it do well under high I/O and in windows cluster?

Thanks.

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7 Replies
AndreTheGiant
Immortal
Immortal

The 2 TB limit is a limit of ESX, for the max disk size.

You can install the initator insede the VM and use iSCSI from there.

Andre

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Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
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AndreTheGiant
Immortal
Immortal

Would our only option be to use VMFS with extends?

Also if you use extent you cannot have a single vmdk or a single RDM greater than 2TB.

Andre

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Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
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TheTechie
Contributor
Contributor

Thanks for your help.

"You can install the initator insede the VM and use iSCSI from there."

We plan on hosting a second SQL server (passive) on the server possible one or two addiitonal low usage servers. Each server was planned to use the SAN to store the OS partition and both SQL servers will need to use the SAN for database & SQL cluster quorum.

My concern is going through initiator in the VM would create network congesstion and possible performance issues on the host server but I guess we'll have to test to find out.

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TomHowarth
Leadership
Leadership

Yes you can, use the Microsoft iSCSI driver internal to the guest and connect directly to the LUNs this will enable you to utilise larger capacity as it understands SCSI3 calls.

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Tom Howarth VCP / vExpert

VMware Communities User Moderator

Blog: www.planetvm.net

Contributing author for the upcoming book "[VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment|http://my.safaribooksonline.com/9780136083214]”. Currently available on roughcuts

Tom Howarth VCP / VCAP / vExpert
VMware Communities User Moderator
Blog: http://www.planetvm.net
Contributing author on VMware vSphere and Virtual Infrastructure Security: Securing ESX and the Virtual Environment
Contributing author on VCP VMware Certified Professional on VSphere 4 Study Guide: Exam VCP-410
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AndreTheGiant
Immortal
Immortal

My concern is going through initiator in the VM would create network congesstion and possible performance issues on the host server

Maybe. But for this reason use 2 or 3 NIC in iSCSI vSwich Smiley Happy

Also use jumbo frame that are supported at VM level (are not supported for ESX software initiator).

Andre

**if you found this or any other answer useful please consider allocating points for helpful or correct answers

Andre | http://about.me/amauro | http://vinfrastructure.it/ | @Andrea_Mauro
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kjb007
Immortal
Immortal

You can also utilize multiple vNICs in the vm and use MPIO for the LUNs to help alleviate some bandwidth issues, if you start reaching the max on one path.

-KjB

VMware vExpert

vExpert/VCP/VCAP vmwise.com / @vmwise -KjB
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habibalby
Hot Shot
Hot Shot

Hello,

You can present another lun to the as rdm to the vm node and split the db's on multiple. Rdm luns.

Best Regards, Hussain Al Sayed Consider awarding points for "correct" or "helpful".
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