On Dec 20, 2010, at 8:58 AM, Brian Mathis wrote: > Doesn't the fact that they have to do this prove the "generalized" > statement? If they need to put RAM in front of the flash, that means > the flash is slower. It sounds like you're talking specifically about > "SSDs", while the conversation is about flash chips which would be > integrated on a RAID card.
The other way that they get ultra high speed out of Flash devices is to use Sandforce (and similar) controllers that effectively do the equivalent of RAID in the background and write out to multiple flash chips simultaneously -- the more chips you have in your array, the higher bandwidth the system can handle. Getting back to Doug's point, not all Flash devices are the same. SLC is not the same as MLC, consumer-grade is not the same as Enterprise-grade, and a great deal depends on the particular Flash controller that is used and how it is implemented. OS support for features (e.g., TRIM) are also a factor. The folks at Sun knew all this when they were putting ZFS together in their storage system hardware, but then unfortunately they got bought. -- Brad Knowles <[email protected]> LinkedIn Profile: <http://tinyurl.com/y8kpxu> _______________________________________________ Tech mailing list [email protected] https://lists.lopsa.org/cgi-bin/mailman/listinfo/tech This list provided by the League of Professional System Administrators http://lopsa.org/
