SaaS data loss: The problem you didn’t know you had
The research team produced a paper in 2010 describing such use with a project called ChunkStash (pdf). That paper said:
ChunkStash uses one flash read per chunk lookup and works in concert with RAM prefetching strategies. It organises chunk metadata in a log-structure on flash to exploit fast sequential writes. It uses an in-memory hash table to index them, with hash collisions resolved by a variant of cuckoo hashing.
Having gained his PhD, Debnath joined EMC last November, as a senior software engineer. He is working in the Backup and Recovery Systems division, the one that houses Data Domain and Avamar. Debnath's LinkedIn entry says his "main focus is to build a scalable index to support large-capacity deduplication systems".
EMC doesn't currently employ servers with cache installed. It does have storage arrays with an enterprise flash drive (EFD) storage tier and this can be used as a general FastCache (flash cache) for the array, caching the array's I/Os in pretty much the same was as NetApp's controller-located FlashCache, and caching both reads and writes unlike the NetApp technology which is a read cache only.
What we might look for from EMC is the provision of Data Domain controllers which have PCIe-connected flash, possibly using Fusion-io, STEC or Violin Memory flash product, and having faster deduplication performance.
As an aside there is potential here for Microsoft to use FlashStore in its own storage products, such as Windows Storage Server. That would require, as per the Microsoft server model, server suppliers to step up with X86 servers incorporating a flash memory tier. Noting that Dell is using Fusion-io in this way already and has bought specialised image and file deduper Ocarina, it isn't too much of a stretch to imagine Dell could be shipping FlashStore-like systems in the future.
In fact, El Reg prognosticators think deduplication system controllers and servers for IOPS-intensive applications could have a flash memory tier as a matter of course in a year or two. ®
COMMENTS
Oye... Not this againnnnnnnn
"NetApp's controller-located FlashCache, and caching both reads and writes unlike the NetApp technology which is a read cache only."
From: http://blogs.netapp.com/efficiency/2011/02/flash-cache-doesnt-cache-writes-why.html
NetApp’s Data ONTAP does something uniquely different from the majority of other storage vendors’ products; it’s optimized for writes. Indeed, write optimization was one of the original design criteria for Data ONTAP back in 1992. Dave Hitz himself explained this many years ago in TR-3001 (since updated). In brief, Data ONTAP eliminates the “Disk Parity Bottleneck” through its use of WAFL to coalesce a group of temporally located write IOs; pre-emptively “defrag” if you will this group of I/Os based upon the best possible allocation unit or “tetris” available; calculate parity for the entire lot while in memory, and stripe the lot of them across all available drives during the next write event (aka consistency point, CP).
"Data ONTAP eliminates the “Disk Parity Bottleneck” through its use of WAFL to coalesce a group of temporally located write IOs" -- That part is done via a write cache battery-backed DIMM(s)...
FlashCACHE isn't FlashSTORE©
Except FlashCACHE isn't FlashSTORE©, see FlashSTOREs got almost totally different letters in its name ..
AC Beat me to it
Oh lookie, Microsoft "inventing" something that NetApp started doing more than 16 years ago and claiming it as new. No surprise that EMC have now decided to use the technology. Ohh Ohh, me too.
I wonder if they will shut up with the WAFL frag FUD.
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