Tag Archives: NFS

Having performance issues with Celerra and NFS Datastore performance ? patch ! Patch ! Patch !

I sat in on an interesting session yesterday which gets under the covers of VMware performance on NFS datastores  hosted on Celerra NS series. This was presented by a chap called Ken Cantrell who works for EMC engineering and was off the back of the fact that feedback from the field showed in many cases that some customers VMware estate simply wasn’t performing using NFS on Celerra. This is not the case for everybody, but it certainly was an issue. Essentially what was happening is the Celerra was dealing with an extensive amount of NFS calls to the UxFS log (predominantly Getattr type calls) and it was slowing down response types back to the host. EMC tested a workload on the Celerra using DART 6.0.4 using Jetstress. Jetstress effectively simulates exchange workload and also halts the benchmark if response times exceed 20 milliseconds on the basis of 20 milliseconds being to poor for a exchange. EMC were seeing that with the base version of DART 6 response time were exceeding 25 Milliseconds for the Exchange workload they tested on an exchange VM sitting on a Celerra hosted NFS datastore. EMC then released a patch upgrade which brought that down to sub 15 ms. EMC then released an experimental epatch (DART which brought response times down further to sub 10ms (closer to 6ms).

So bottom line is…  don’t just suffer poor performance. Feed back to EMC if you see issues and also keep an eye on patch updates to the OS. They are there to resolve noted issues !


A good post on ECN with details of the new patch :


A good blog comparing iSCSI Vs NFS for VMware:


A good blog post by Jason Boche comparing the performance delta between Dart 6.0.4 and Dart


Iomega/EMC’s new lovechild

Iomega first started life selling removable storage. The world marvelled at the might of the 200MB Zip drive, brought gifts of  gold , frankincense and murr as offerings to the almighty Jazz drive and sacrificed livestock in awe of the the Ditto Drive  (I exagerate..  but bear with me, I’m setting the scene). Then, as removable storage media started to give way to internet and USB drives became the standard for removable storage..  we started to see the likes of the zip and jazz drive fade away.

So..  out with the old, in with the new ? No..  Now Iomega have a massive play in the consumer space for External Hard drives and networked storage. The upper end of the networked storage range was the IX4 (now on its second generation). A nice tidy box which would hold up to 8TB of RAW capacity and fit well in a remote office environment, home office, even as a media server for your movies and music (all legitimately obtained of course). They even did a rackmount NAS device..  Brilliant !!

But what if you need a little more grunt… a bit more redundancy, scalability.. something more feature rich. Iomega/EMC are on the verge of releasing the IX12. This box fits nice and snug between the IX4-200R and EMC’s Celerra NX4; it supports up to 24TB of RAW capacity, supports all the RAID types you’d ever want to use and has 4 Gigabit ports which can support up to 256 iSCSI initiators (servers) or 256 LUN’s for block level access. All the other usual protocols still apply in the oh so familiar forms of CIFS, NFS, FTP, HTTP, etc and there are even a few nice bells and whistles such as port aggregation, DFS, array based replication, WebDav Support for online collaboration and it also sports drive spin down (very cool if its being used for a backup to disk or archive target). 

The IX12 has also been certified by a number of other vendors; it is obviously certified and on VMwares Hardware compatibility List for shared storage (also supported by a number of other virtualization vendors). Microsoft have verified that it will support Exchange 2010 Mailstores for environments of up to 250 users.

Its being stated by Iomega that these boxes are sitting in at between $5,000 and $10,000 list,  so will help EMC break even further into the lower SMB market. Personally, I think this box will play really well in spaces such as remote office,  graphic design organisations, departmental dedicated storage, backup to disk targets (admittedly would be more compelling if it supported NDMP, but we’ll leave that to the big boys), archive storage for the likes of EMC’s SourceOne, EV, Commvault, etc…

I’ll put together a more clear and concise post after the announcements to come, but I think Iomega could be onto a winner on this one..