Diggin' technology every day

November 24, 2010

More inefficient storage

Filed under: Storage — Tags: , , — Nate @ 8:32 am

Another random thought, got woken up this morning and wound up checking what’s new on SPC-1, and a couple weeks ago the Chinese company Huawei posted results for their Oceanspace 8100 8-node storage system. This system seems to be similar to the likes of HDS USP/VSP, IBM SVC in that it has the ability to virtualize other storage systems behind it. The system is powered by 32 quad core processors or 128 CPU cores.

The thing that caught my eye is in every SPC-1 disclosure is the paragraph

Unused Storage Ratio: Total Unused Capacity (XXX GB) divided by Physical
Storage Capacity (XXX GB) and may not exceed 45%.

So what is Huawei’s Unused storage ratio? – 44.77%

I wonder how hard it was for them to get under the 45% limit, I bet they were probably at 55-60% and had to yank a bunch of drives out or something to decrease their ratio.

From their full disclosure document it appears their tested system has roughly 261TB of unused storage on it. That’s pretty bad, 3PAR F400 has a mere 75GB of unused capacity (0.14%) by contrast. The bigger T800 has roughly 21TB of unused capacity (15%).

One would think, that for Huawei, they would be better off using 146GB disks instead of the 300GB, 450GB and 600GB disks (another question is what is the point in mismatched disks for this test, maybe they didn’t have enough of one drive type which would be odd for a drive array manufacturer – maybe they mixed drive types to drive the unused capacity perhaps after having started with nothing but 600GB disks).

Speaking of drive sizes, one company I know well has a lot of big Oracle databases and are I/O bound more than space bound, so it benefits them to use smaller disk drives, their current array manufacturer no longer offers 146GB disk drives so they are forced to pay quite a bit more for the bigger disks.

Lots of IOPS to be sure, 300,000 of them (260 IOPS per drive) and 320GB of cache (see note below!), but certainly seems that you could do this a better way..

Looking deeper into the full disclosure documents(Appendix C page 64) for the Huawei system reveals this little gem

The creatlun command creates a LUN with a capacity 1,716,606 MiB. The -p 0 parameter, in the creatlun command sets the read cache policy as no prefetch and the -m 0 parameter sets the write cache policy as write cache with no mirroring.

So they seem to be effectively disabling the read cache and disabling cache mirroring making all cache a write back cache that is not protected? I would imagine they ran the test and found their read cache ineffective so disabled it and devoted it to write cache and re-ran the test.

Submitting results without mirrored cache seems, well misleading to say the least. Glad there is full disclosure!

The approximate cost of the Huawei system seems to be about $2.2 million according to the google exchange rate.

While I am here, what is it with 8 node storage systems? What is magical about that number? I’ve seen a bunch of different ones both SAN and NAS that top out at eight. Not 10? not 6? Seems a strange coincidence, and has always bugged me for some reason.

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