Comments on: Monster VMs & ESX(i) Heap Size: Trouble In Storage Paradise

By: Heads Up! New Patches for VMFS heap |

Heads Up! New Patches for VMFS heap | — Thu, 11 Apr 2013 13:01:56 +0000

[...] with a blog articles on the vSphere blog by myself, but also articles by such luminaries as Jason Boche and Michael [...]

By: Eric

Eric — Tue, 19 Mar 2013 17:47:00 +0000

Is there any reason “not” to just max out the heap size? I presume there’s a reason VMware set a smaller value. Is memory usage, the only con to increasing it? Meaning, is there any performance overhead with increasing the setting?

By: Eric Miller

Eric Miller — Mon, 07 Jan 2013 03:21:11 +0000

This certainly is disconcerting, especially since backing up VMs requires mounting VMDKs to a backup virtual appliance. I wonder if, by snapshotting, and mounting the disks to the backup appliance doubles the amount of “open vmdk file space” for a given vmdk.

Scalability seems to have always been low on the VMware priority list, in my opinion.

Eric

By: Joe Tietz

Joe Tietz — Wed, 28 Nov 2012 18:38:28 +0000

I have Agree with Roger this is good thing to know. I just ran in to this issue in a SQL POC. Wanted stress test the hosts with fauiled host.. Last 5 VM’s could not be moved becuse of heap error. We are all VMDK’s and all block storage at this time.

By: Deploying Enterprise Oracle Databases on vSphere « Long White Virtual Clouds

Tue, 23 Oct 2012 17:10:09 +0000

[...] [...]

By: Roger lund

Roger lund — Sat, 22 Sep 2012 23:29:46 +0000

Gah, this is a serious problem in my eyes. I have a DRV program that requires up front partitioned space (thick) when on block. With the space retention requirement the client has, the disk requirement is 45tb. A single 45tb drive is preferred. In some storage platforms rdms are not a option, and multiple vmdks would be the only choice, then requiring a very large dynamic disk within windows.

The lack of large disk support like this is staggering.

Roger Lund.

By: Joe Tietz

Joe Tietz — Mon, 17 Sep 2012 15:53:23 +0000

Starting to think that NFS might be wave of the future for VMware. With software defined storage around the corner no reason not to simplify and present it all as NFS.

By: The Case for Larger Than 2TB Virtual Disks and The Gotcha with VMFS « Long White Virtual Clouds

Mon, 17 Sep 2012 11:35:34 +0000

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By: Storage Sizing Considerations when Virtualizing Business Critical Applications « Long White Virtual Clouds

Sun, 16 Sep 2012 22:14:37 +0000

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By: jason

jason — Fri, 14 Sep 2012 19:24:07 +0000

There are some questions in the comments section about what types of stoarge the heap size constraint applies to. VMware has confirmed that heap size and max virtual disk capacity per host applies to VMFS only. The heap size constraint does not apply to RDMs nor does it apply to NFS datastores.

By: Drew

Drew — Fri, 14 Sep 2012 13:36:06 +0000

Great article. I too am curious if this also affects NFS. I have several 5.0 host that have more than 8 TB of storage open on them and I haven’t had any issues yet… But we are running NFS, so I wonder if NFS is not affected by this.

Anyways, thanks again for a great article and pointing this out to the community.

By: Shaun

Shaun — Thu, 13 Sep 2012 20:43:47 +0000

Found this interesting article about the subject:
http://virtualkenneth.com/2011/02/15/vmfs3-heap-size-maxheapsizemb/

Its saying that the 25TB max size isfrom using a 1MB block size ( VMFS5 would be using this ). Using an 8MB block size will allow up to 160TB using the default 80MB heap.

I’m not sure how true this scenario is or if this changes with ESXi 5.1

By: jason

jason — Thu, 13 Sep 2012 20:23:55 +0000

@Shaun

That’s a really good question. The KB article solely mentions VMFS but at the same time it calls out often that it’s an open virtual disk per host issue which would apply across the board. I will do some more digging and see if I can an answer on this.

By: jason

jason — Thu, 13 Sep 2012 20:14:36 +0000

Applies to VMFS-5 also. Don’t be thrown off by the “VMFS-3″ advanced configuration label. That applies to 5 as well.

By: Killian

Killian — Thu, 13 Sep 2012 17:56:28 +0000

Does this apply to all storage or just VMFS? Does NFS have any of these limitations?