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August 30, 2011


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I am an NFS fan so i'm happy with thah news.
But with the namespace cluster nexenta can make scale out infrastructure. And with the zill of zfs all the transactionnal operation are cached on SSD or RAMDISk so all problem are gone in fact xD.



Good Stuff. Isilon is uber upcoming and really changes things. My question is that do you still have latency issues when Isilon acts as an iSCSI target? If so, is it the architecture that causes this OR is it something else?

A Facebook User

So, Basically an XIV type solution for block or GPFS or SONAS for NFS ?
Many brains serving the same data.


This behavior, "scale-out NAS systems (even the best) typically have transactional latencies that are about 2x-3x the latencies of “Type 1” block and NAS systems, and “Type 2” block systems"...is a problem specific to Isilon's OneFS filesystem (a known issue). It is not the same behavior in other NAS systems with scale-out capabilities. That is why Isilon is not (yet) suitable for VMDKs. Get those latencies worked-out, and you'll have a great solution...as you have boasted. But I see you've covered yourself by saying "...no mainstream scale-out NAS competitors...", which compartmentalizes your claims to only EMC & NTAP who own 70% of the market. Look at Oracle ZFS, IBRIX with 3Par, and Symantec-Huawei Filestore...all have scale-out and support transactional processing of small IO for low latency. Bring us API compatibility for Storage Awareness & Array Integration for Isilon, and folks may start to overlook the latency problems...

Chad Sakac

@nOon - the point was that global namespace models (Nexenta example, but also all similar ones) don't have the same characteristics around "all files accessible via all nodes" that makes the scaling (and failure models). I'm a fan of open ZFS, but worry a little about how Nexenta is going to run with that ball with OpenSolaris going the way it is.

@A Facebook User - XIV, EqualLogic, 3PAR, VMAX are all architectural examples of the block scaling model. We would argue about better/worse and functional capabilities - but yeah, they are examples of the model. GPFS and SONAS are (and don't take me literally here - I'm not an expert on other folks) examples of global filesystem models that are different - metadata hosts and redirection.

@chappy - the iSCSI latency thing is still there. It absolutely works - but is a result of the core thing I'm pointing out (architectural challenge of "loosely coupled" distributed systems. It's not a protocol thing (iSCSI doesn't make it worse or better), it's intrinsic. Believe me - it's the top priority (for NAS and iSCSI use cases) for folks at Isilon.

@mobiuslink - I'm not sure if I agree. First of all, NetApp's approach is a globalnamespace approach, different (not saying not valid, but similar comments to @nOon). Also, all the data I've seen (look at the SPEC SFS results here: http://www.spec.org/sfs2008/results/sfs2008nfs.html show that SONAS, Filestore, IBRIX and other "loosely coupled" models show the same latency models. They all (including Isilon) use variations of NVRAM, SSD to minimize the distributed metadata and loosely coupled model. If there's public data to share - please, please link it! Also notable in the "fine print" is the number of filesystems used in these tests.

Remember all - I'm not saying these models are BAD, but rather that until they can serve an 4K 8K, 16K IO in 5-10ms, there's some workloads they are JUST NOT a fit for...


Very good stuff, I'm setting up a big Isilon right now.


Hi chad,

i'm still working on article relative to our meeting in france at the beginning of february.

This article is quite cool to help me understanding all you've told us this night :)

and guess what ? 2013 is now for me storage's year for I need to be more loaded on this ;)

best regards !

Thomas aka VirtTom

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