Isilon gets thin with phat storage app
Thin-provisioning. It's all the rage
Storage vendor Isilon Systems has hopped aboard the thin-provisioning express that's chugging through the industry, adding the sought-after technology to its clustered storage products as a part of today's hardware and software revamp.
The new software, called SmartQuotas, combines quota management and thin provisioning into one software application. Isilon reckons its the first in the industry to combine the two for clustered storage. SmartQuotas allows users to partition a single, scalable, shared pool of storage (up to 1.6 petabytes) and assign limits on how much storage a particular user or group can access.
Thin provisioning is the new virtual storage darling, and companies are falling over themselves to add it to their lineup. Originally developed by 3Par, thin provisioning reduces wasted free space on a SAN by allowing a volume to occupy only the physical disk space it immediately needs. For example, a 5GB volume with only 50MB of data will only occupy 50MB on the array. Industry eyeballs will note companies such as EMC, HP, Hitachi and NetApp have lately been busy fleshing out their thin provisioning offerings as well.
SmartQuotas runs on Isilon's OneFS operating system, which powers all of the company's Isilon IQ line of clustered storage systems. The OS uses a single file system, managing and presenting the total capacity to the host as a single disk drive. Similarly, the processors and memory from each node are treated as a single raw capacity.
In addition to the new software, the company has announced a hardware revamp that adds a 50 per cent capacity improvement to its previous high-end IQ offering by replacing 500GB SATA disks with 750GB. This move crams a maximum of 1.6 petabytes into the new IQ 9000 system, which replaces the IQ 6000 as the company's top-of-the-line.
The IQ 9000 holds twelve Seagate 750GB SATA disk drives, increasing the node capacity to 9TB. A total of 96 nodes can be combined into a single cluster. Customers can increase the size of the cluster by adding additional nodes through the 9000's two InfiniBand ports and 2Gb Ethernet ports or by adding expansion cabinets existing nodes.
Isilon has also released the EX 9000, a disk-only expansion node for the IQ 9000. The expansion adds an additional 9TB of raw storage capacity.
The Isilon IQ 9000, which comes as a complete system, is priced $4,100 per terabyte or $37,250 per node. The 9000 requires at least three nodes to run a cluster.
The EX 9000 costs $22,250 per node — which can be bought individually — or $2,500 per terabyte.
SmartQuotas is priced at $1,950 per node. All the hardware and software are available immediately. ®
And shortly after this comes up, there's an article about LeftHand.
thin provisioning is pretty neat
My company bought a 3PAR E200 a few months ago and have been using thin provisioning exclusively. It's pretty cool stuff. Though one thing to keep in mind is the provisioning is one-way(at least with 3PAR, I'd assume the others are the same). e.g. if you create a 1TB volume, and write 300GB to it, it consumes 300GB(+ raid overhead) on the array, if you then erase that 300GB, it still consumes 300GB on the array. Since the array has no way to safely determine if the space as been freed so it cannot reclaim it.
I expect to see in the coming years more intelligence between the array and the file system to allow safe, automatic "un-provisioning" of space when significant amounts of space is deleted.
Our array is fairly small, just 2 shelves with ~8.6TB usable. We have about 24TB of space that is thinly provisioned(29TB if you count snapshots, which 3PARs management tools count as virtual space when showing space usage), with roughly 6.1TB of physical space being used.
3PAR also allows you to set a warning threshold as well as a block I/O threshold, so you can guarantee that a particular volume won't use more than X amount of space if you want. Not sure if the other vendors offer this. An example of this in action is I set an oracle standby database logfile volume to warn at ~50% space utilization and block I/O at ~85%. The file system was using a small fraction of that(under 10%). But due to a long running snapshot, it ate up a lot of space over time, and one night the array hit the limit and it blocked new writes to the volume. The linux host was spewing scsi errors and oracle was bitching for hours until the morning when I saw the errors and removed the restriction. Oracle continued on as if nothing happened(no restart or anything).
3PAR support contacted me as a result of the SCSI errors and decoded the error saying it was reporting an out of space condition(something I wasn't aware was able to be communicated over the scsi protocol, I thought it was purely a file system thing). -- (with 3PAR in thin provisioned volumes snapshot space can be unlimited when it is tied to the parent volume)
Unless you have gobs of physical space it's important to stay on top of space utilization when using thin provisioning until you get a good handle on how it behaves with your applications, because the growth may not be what you expect, since array provisioning and file system utilization may be significantly different. I've rebuilt file systems that were consuming 500GB on the array but using less than 80GB on the file system itself because of lots of adds and deletes(on a 1TB volume).
At one point during talks with 3PAR they told us they were going to have us sign a document that said we understand the thin provisioning technology and agree that if we mis-use it(over allocate without proper planning) and it causes problems(run out of physical space) then it's our fault since we got training on it. Well they only ever told us that once, and we never saw the document. Not sure if they just forgot or maybe changed their minds. But in any case I've been watching it closely as we get closer to our physical capacity limit.
And we're still very much in the learning phase. We have 19 servers connected to the E200, it's been a great array for consolidating our storage needs. Really fast, real easy to use.