Hard drives get even harder

Storage Expo If your applications are slow even on Fibre Channel hard disks, Baydel reckons it has the answer - a 3.5-inch 4Gbit Fibre Channel drive full of Flash memory.

The devices are called Maracite and run up to 146GB each. Baydel's also offering four of them in a 1U rackmount chassis called FlashStor, so you can have half a terabyte of super-fast RAID.

Baydel boss Tony Bedingfield claimed FlashStor is capable of over 100,000 I/Os per second. "We build the drives in the UK, using conventional NAND Flash modules," he said. "It looks exactly like a dual-ported Fibre Channel disk, except it's 150 times faster."

He added that some servers may not be able to deliver enough I/Os to fully stretch the Flash storage. "The latest QLogic HBA is the only one we've found fast enough, and for our demo we had to use Veritas as Windows mirroring was too slow," he said.

Baydel's already scored one win for FlashStor, selling a 144GB four-drive unit to the UK Serious Fraud Office. The SFO is using it as working storage for its huge database of scanned documents, and said it has reduced the time needed to re-index the database from weeks to days.

Even with prices as high as £800 per GB - though larger models are cheaper - Maracite costs less than RAM-based solid state disks (SSDs) from the likes of Texas Memory Systems.

It is slower than RAM though, and Flash memory also has a limited lifetime, as each cell can only be written to perhaps 10,000 times before failing.

Bedingfield acknowledged that, but said Baydel has added write-balancing algorithms and 12-bit error checking - along with the Fibre Channel interface and drive emulation, this accounts for the high cost, he said - and claimed this should give the drives a life of 12 years, based on a constant 5000 I/Os a second.

Flash's other problem is that it's good at reads but slow at writes, pointed out Woody Hutsell of Texas Memory Systems, which launched a new low-end DDR RAM-based solid state disk (SSD) at the show.

He said that potential SSD users need to ask: "If they advertise good I/Os per second, can they sustain that, and under what conditions?

"DDR gives better write performance and has no wear limit. All the Flash drive manufacturers do wear levelling, but some of our customers could hit that 10,000-write limit fairly rapidly."

Starting at £15,000 for 16GB, the new TMS RamSan-300 is more expensive than Flash SSD but is several times faster. However, it is also several times larger - the RamSan-300 and its big brother the 128GB RamSan-400 are both 3U rackmount boxes.

Hutsell said this is partly because RAM runs hotter so needs more airflow, and partly because the boxes also contain batteries and hard disks, so if the power fails, the contents of the SSD can be automatically backed up.

He added that different SSDs will suit different uses, with Flash good for read-only or read-mostly and RAM for write-heavy applications.

"Flash has been cheap all year and we've still grown our business 50 per cent, so there's plenty of room for growth," he said. ®