frenchj991
Contributor
Contributor

Is it better to have multiple small datastores or 1 one large?

Hello,

We have 3.3TB of space in a SAN that will be assigned to our vmware servers.  From a performance aspect is it better to create multiple smaller logical drives on the SAN or 1 large logical drive?

Thanks,

Jeff

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8 Replies
a_p_
Leadership
Leadership

I assume you have 3.3TB Smiley Wink

It may depend on the virtual machines and their workloads. I ususally go with ~600 GB per datastore.

André

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idle-jam
Immortal
Immortal

Second André, the max datastore you can go is 2TB-512k hence with that 600GB would be a sweet spot.

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Hoschi201110141
Enthusiast
Enthusiast

3.3 TB?

Each Design depends on diffrent need's.

I sugest to create multiple LUNS/Datastore. A single Datastore sems easy for Administration but have some hocks...

SCSI Reset's and so on.

The Size can depend on your need's or the best way in conjunction to the Storage Array Configuration (Raidgroups).

My LUN's has a 256 GB Size.. in my Environment that let me run 3-5 VMguests on each LUN. It works fine for me.

Greetings

hoschi

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frenchj991
Contributor
Contributor

so how does that work for configuration wise say if you needed a server that had to have a large amount of space assigned to it, i.e several TB.  Do you have a bunch of LUNS that you need to combine to create one large vmfs store?  Does having a lot of smaller LUNS not increase the chance of failure?

Jeff

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DSTAVERT
Immortal
Immortal

The maximum LUN size that ESX(i) will recognize is 2TB minus 512 bytes so you will at least be limited to that. It can be extended through extents but not a wise Idea. You can assemble smaller VMDKs using DFS in Windows or Mount points in most OSs including Windows.

-- David -- VMware Communities Moderator
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depping
Leadership
Leadership

2TB is the supported max for a VMFS volume without extends. I would recommend carving it up in 3 equally divided volumes.

Duncan (VCDX)

Available now on Amazon: vSphere 4.1 HA and DRS technical deepdive

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matthewharman
Contributor
Contributor

When I originally setup my esx 3.5 cluster, I setup a single nfs datastore, to our netapp filer.  That was three years ago and it has served us well with no major issues.

We are now getting ready to replace the single head Netapp with a dual head active/active unit, where we will have to split the datastore into at least two volumes so as to balance the load across shelves/heads.

I have recently spoken to a consultant who recommended a balance of 20/25 vms per datastore, with attention paid to the demands of each vm so as to balance the load well.  The suggestion was to try and group vms with the same OS in the same datastore so as to maximise the de-duplication function of the Netapp.

So if your storage has de-dupe capabilities, design your storage layout to maximise the benefit of this.

Esx 3.5 allows 32 nfs datastores, subject to changing the parameter in the configuration, advanced settings.  I believe this limit is further raidr in vsphere.

There are also other parameters vmware advising changing for nfs datastores in the config guide.

Hope this helps!

Matthew

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samansalehi
Enthusiast
Enthusiast

Dear Freind, I have 4 LUN with 2TB storage for each, sum= 8TB.

I just say the benefits of Large Disk Space LUN:

     i have a Backup server, i use one vHardDisk for windows on one LUN and add another vHardDisk about 2TB for the backup partiotion on another LUN.

     so sometimes the Big LUN will Help u.

     The problem of low disk space that it may u cannot optimize all the space and provison it, for example if u have 250GB and provision 45GB for 5 VM, 25GB free spce that may unusable.

If it is helpful, would u please mark it as "Helpful" or "Correct"?

thank u

Saman

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