LUN Design

[tasonis]

What are some best practices on LUN setup. Our backup software is CA 11.5 and our SAN is an Equallogic PS100E. Should we create one large VMFS LUN for VM storage or multiple, small LUNS? Data drives will each have their own LUN but would one large one for VMDK's make management easier as well as allow room for snapshots? What are the pro's/con's?

[EGRAdmin · Accepted solution]

As a rule of thumb I never use extents for production environment machines.

They can break and you'll have a major headache when you try and repair what is left.

I would use LUN extents only if absolutely necessary. I use them for a secondary backup repository.

It's really based on how many LUN's you think you'll have and how much you want to document and manage.

Right now 256 is the max LUN's per host and 32 is the max paths to VMFS volumes. So I generally stick to smaller LUN's and have 3-4 systems per LUN on small LUNs (and more per 100GB of space).

It would really depend on your expected growth. Generally speaking 300GB-500GB drives are good drives to work with in my experience.

I would keep 10-20% of storage space available for snapshots, or more depending on how agressive your stratagy is.

[esiebert7625]

I think in general you will find alot of people like to keep their LUN size around 500-600GB. I prefer the less complicated approach of a single VMDK file for most of my servers. The exception being file servers which I create a small boot partition as a VMDK and RDM's as the data disks. Here are some links/threads that talk about this...

VM Disk Scenario's and Performance -

Separate VMDK files or partitions within Windows - http://communities.vmware.com/message/787607

SAN Configuration Guide -

SAN Conceptual and Design Basics -

SAN System Design and Deployment Guide -

Vmware Infrastructure 3, HP StorageWorks best practices -

LUNS - http://www.vmware.com/community/thread.jspa?messageID=333672

LUNS Size -

Sizing LUN for enough free space after VM -

Smaller LUNS or Larger LUNS -

Larger LUNS = More Disks = More Performance -

Layers of Virtual Storage in VMware VI3: Configuration without Confusion -

Choosing and Architecting Storage for your Environment -

ESX Server Raw Device Mapping -

Extending a VMFS3 data store - http://www.vmware.com/community/thread.jspa?threadID=65156

To use extents or not? - http://www.vmware.com/community/thread.jspa?threadID=81494

VMDK vs. RDM - http://www.vmware.com/community/thread.jspa?messageID=662212

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[tasonis]

I would like to put my server "C:\" drives as VMDK's in one large LUN (to reduce managing LUNs via ESX). I would then create separate LUNS for each data drive (i.e database storage, etc.), but connect through Microsoft's iSCSI initiator to use MPIO (we've noticed better performance this way).