TMS buckles up first MLC flash product
Suffering from smeary stripe? This cleans up in stride
News from the flash front: TMS has a more affordable small flash SAN product that's higher capacity than the RamSan 710 speed rocket.
The multi-level cell (MLC) RamSan-810, has MLC flash replacing the faster single-level cell (SLC) in the 710 which was announced in June.
TMS has its RamSan-630 product for large SANs, the 710 and now 810 for smaller SANs, and RamSan-70 for direct PCIe-attached server flash.
The company is seeing that enterprise-grade MLC (eMLC) is now reliable, fast enough and has a long enough endurance to be used alongside its SLC-based product range. MLC flash, with its 2 bits per cell, is slower than SLC, more affordable, yet has a shorter endurance. Controller technology, such as signal processing to better read data from MLC cells, and over-provisioning, up to 30 per cent, can compensate for this.
TMS has variable stripe RAID (VSR) technology which dynamically varies the RAID stripe length to bypass one or more failed flash chips, dies or planes. Each RamSam NAND chip has 8 dies in it. One or more dies can fail but the controller can carry on using the other dies.
VSR is a technique to bypass single or multiple bad chips, dies or planes anywhere in the RAID stripe. Flash, compared to hard disk drives, is so fast that such RAID system reconstruction can be carried out dynamically.
The 1U rackmount RamSan-810 has up to 10TB of usable capacity, based on Toshiba eMLC NAND, and provides 320,000IOPS with 4GB/sec bandwidth. It has four I/O ports; 8Gbit/s Fibre Channel or quad data rate InfiniBand, and uses the same controller as the 710.
A rack stacked with 810s would have half a petabyte of flash capacity.
In endurance terms the 810 can sustain five full writes a day for ten years. In capacity terms it has double the 710's 5TB and is up with the 630's 10TB. It seems apparent that an eMLC version of the RamSan-630 could come along, with 20TB capacity. TMS CEO Holly Frost said: "It sure looks that way, doesn't it."
We could also conceive of an MLC version of the RamSan-70 with a 1.8TB capacity.
Frost believes that eMLC products will expand TMS's addressable market and not cannibalise the SLC products. He says the 810 is a good for for applications such as data warehousing and acquisition, web content hosting, and other apps needing lots of I/O reads but fewer writes.
TMS seems to have a steady rate of product introductions, with a new product coming along every three or four months. On that basis we can look forward to another RamSan something by the end of the year.
The RamSan-810 is priced at half the cost per TB of the 710, with a 10TB RamSan-810 costing the same as a 5TB 710. ®
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