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SSDs: Your mileage almost certainly will vary

Maybe this is what happens with any brand-new technology, but so far there’s been such wide variability in the solid-state drives that have been announced for the enterprise since EMC added STEC drives to Symmetrix last January that I can’t help but be curious about it. Here are the specs available on some of the latest SSDs rolled out:

  • STEC (as used by EMC):  73 GB and 146 GB, FC interface, 52,000 sustained random read IOPS; 17,000 sustained random write IOPS; 250 MBps sustained, sequential reads; and 200 MBps sustained, sequential writes.
  • Intel X-25 E: 32 and 64 GB, 170 MBps sequential write; 4 KB random-read IOPS 35,000; random writes at 3,300. 10 I/O channels on controller. Claims smaller write amplification than other drives.
  • pureSilicon: SLC capacities of 256 and 512 GB. MLC capacity of 1 TB. Up to 50,000 random read IOPS. 32 channels on controller.
  • Samsung: 100 GB; 25,000 random read IOPS; 6,000 random write IOPS; read data sequentially at 230 MBps and write sequentially at 180 MBps. Also claims to have a new ‘recipe’ for NAND Flash material itself that could boost SSD durability, but hasn’t decided when, where, or how to release it to OEMs.

This week I’ve also come across Toshiba, which announced a new SAS interface SLC drive in a 100 GB capacity this week. But it’s the darndest thing–another drive, another very different claim about random read and write IOPS–for Toshiba, the numbers are much closer together than they are for others with these two specs: 25,000 random read IOPS, and 20,000 random write IOPS.

The problem is trying to get any of these vendors to drill down further. Most of them won’t because it’s getting into proprietary information, which I understand, but I wish it was somehow otherwise. At most, I’m told it has to do with the number of channels in the controller, the Flash recipe, how many channels are dedicated to reads vs. writes, how data streams are interleaved and/or cached with DRAM on their way into or out of the Flash capacity. It gives me some idea, but I can’t wait until users start testing these in volume, in real world environments.

I also wonder whether the “biodiversity” of creatures in the SSD habitat will continue, or whether eventually enterprise SSDs will commoditize like any other storage medium. There’s some debate about this in the industry so far.