Fram approaching in front of iceberg upernavik, copyright Kim Hansen

Solid state (NAND flash) storage is all the rage right now, but there are many lingering questions regarding its true performance, reliability, and cost. But no question is more important in determining its ultimate usefulness than that of location: Where should flash storage be placed to maximize return on investment?

Storage companies have argued that flash disks can be used most effectively in external storage devices, arguing that it’s simpler to just leverage existing storage technologies. Server companies have tended to prefer to place it inside the server, asking why, if flash disks are capable of massive random I/O performance and extremely low latency, one would put them at the other end of a Fibre Channel or iSCSI connection, which introduces latency and tends to combine I/O operations? 

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Yes! Compellent has just announced at Storage Networking World that they’ll be adding enterprise solid state drives (SSDs) to their excellent fully-virtualized storage arrays. Why is this worth shouting about? Simply because their automated block-based tiered storage architecture ought to be able to really take full advantage of the performance offered by SSDs. If you’ll pardon the pun, SSD in a Compellent array is positively compelling!

Let’s take a second to review: EMC became the first modern storage vendor to include NAND flash-based solid state drives as a standard tier of storage in an enterprise storage product when they announced flash in the Symmetrix DMX in January. Although every other vendor has made “me too” comments since then, enterprise flash remains pretty rare. Could Compellent really be the second major vendor to actually do something, coming along 10 months later?

More than a year ago, I rhetorically asked where the enterprise solid state drives were. In that post, and others that followed, I suggested that SSD wouldn’t really “work” as a mainstream tier unless a storage array was smart enough to dynamically allocate content to this “tier-0″ in a granular fashion. In other words, adding a big lump of flash to a static storage array and trying to manually allocate it on a LUN-by-LUN basis to hot applications is not likely to meet anyone’s cost/benefit sniff test!

But if a post-RAID storage system was smart, it could really make use of the technology, and that’s what makes Compellent’s announcement so interesting. They dynamically move blocks (rather than the much-bigger LUNs) around, and could thus make a smaller amount of flash go a lot further. Add a few flash drives and let the system tune itself! This is a big differentiator, folks!

Of course, this is not just Compellent’s advantage. Any fully-virtualized system could do the same, and we’ve heard such talk from folks as diverse as HP (I’d love to see it in both EVA and LeftHand), IBM (for real in SVC, not the science experiment), Sun (combined with ZFS), Dell/EqualLogic, and I’d love to hear it from 3PAR. Bring it on, folks! Listen to Greg!  Let’s get this technology integrated, tested, released, and in the field!

Update: Compellent probably won’t ship their SSDs in volume ’till Q1. But Chris Evans seems to agree with me 100%, and Dell is talking SSD (but no promises yet).

This is part of an ongoing series of longer articles I will be posting every Sunday as part of an experiment in offering more in-depth content.

Although many discussions in the storage industry focus on the relative merits of one protocol or another, the conversation occasionally turns to the core issue at hand: We continue to patch together a system based on outdated concepts. Most storage protocols continue to mimic direct attached storage, and most of our so-called networks act as point to point channels. An ultra-modern virtualized storage infrastructure with all the latest bells and whistles still holds the concepts of block and file at its core. Whenever the storage industry has tried to bring about real storage management they have been stymied by a lack of context for data.

No amount of virtualization, and no new protocol, will fix this. Put simply, we need a storage revolution. Continue Reading »

I’ve long hollered that ZFS is a real storage revolution in the making, but recognized that it still had a way to go before replacing UFS, HFS+, and most volume managers. Well, a little Rhode Island company called greenBytes comes out of stealth today to announce that they’re doing just that - taking the solid ZFS core and adding some serious enterprise storage features to it. And they’re rolling the lot into a multi-protocol storage array using commodity (Sun Thumper) hardware. These guys have cooked up a seriously interesting entrant in the storage market, though I can’t say much for the decapitated camel-case spelling of their (already in use) name!

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This is part of an ongoing series of longer articles I will be posting every Sunday as part of an experiment in offering more in-depth content.

It has been the core technology behind the storage industry since day one, but the sun is setting on traditional RAID technology. After two decades of refinement and fragmentation, we are abandoning the core concepts of disk-centric data protection as storage and servers go virtual. Next-generation storage products will feature refined and integrated capabilities based on pools of storage rather than combinations of disk drives, and we will all benefit from improved reliability and performance.

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ZFS really piques my interest, so I just had to include it in my TechTarget storage virtualization seminar series.

Here’s a quick primer for those of you who aren’t familiar with it, and thus are wondering why anyone would get stoked over a filesystem!

ZFS (originally “zettabyte file system” but now just ZFS) takes the essential technolgy from file systems and volume managers and stirs it together into one important new way to manage storage.  It’s an open source project started and managed by Sun, using the CDDL license (so Richard Stallman wouldn’t approve).  It’s loved by both Sun and Apple which makes it much more important.

See, ZFS will probably replace UFS (on Sun), HFS+ (on Mac), and every other file system and volume management product out there, especially on these platforms.  And I expect to see it appear on Linux once the tricky bits are resolved (which have to do with licensing not technology…)

ZFS creates a truly flexible, extensible, and full-featured pool of storage across systems and disks.  No more (of the old) arcane syntax, commands, ridiculous GUIs (ahem, Sun), and unnatural limitations of old system storage management.  With ZFS, you add some disks, get some space, and use it.  But it gets cooler than that…

ZFS “zpools” (file systems) live on “vdevs” with striping and optional RAID-Z/Z2 (which is double-parity kinda like RAID-6).  And, get this, every block is protected with checksums to ensure that the rapidly rising incidence of disk errors won’t bite you.  Want capacity?  128-bit addresses mean near-infinite space (in theory).  Oh, yeah, and all blocks are “copy-on-write” for snapshots and clones, something that barely works on most desktops and workstations.

But alas, there are some limitations…  Adding (and especially removing) vdevs is hard (read: maybe impossible) depending on how your storage was set up.  Stacked RAID is impossible, so no “Z+Z2″ for you!  And, until Sun integrates Lustre, there is no clustering support.

And then there’s the fact that Sun and Network Appliance are actively suinging each other over the fact that the technology in ZFS has ended up looking an awful lot like their bread and butter super file system, WAFL.

So there you have it.  If you’ll be in Washington DC on March 4, or Durham NC on March 6 and are interested in this topic, and the wider world of storage and server virtualization, I’d love for you to register and attend this free seminar!