New Seagate SSD and Hard Disks

re: New Seagate SSD and Hard Disks

Greg Linwood — Wed, 16 Mar 2011 12:29:33 GMT

Interesting update Joe - why don't you cover Fusion-io?

re: New Seagate SSD and Hard Disks

jchang — Wed, 16 Mar 2011 12:53:19 GMT

Because this is an update for very recent news. Fusion-IO came out with PCI-E gen 2 products last year?, way before anyone else. But I don't believe they released anything very recently. Last fall, I did a survey of SSD, from NAND to controllers to SSD, which mentioned the Fusion-IO.

Now other players are coming out with PCI-E gen 2 or SAS/SATA 6Gbps SSDs.

re: New Seagate SSD and Hard Disks

Greg Linwood — Wed, 16 Mar 2011 20:45:56 GMT

Fair enough.. Fusion-io recently released "direct cache" which isn't a hardware device but is a pretty big innovation. It's basically a software driver that allows a Fusion-io device to be used as an I/O cache, effectively enhancing the size of a storage system's cache by using the Fusion-io's flash locally..

re: New Seagate SSD and Hard Disks

jchang — Thu, 17 Mar 2011 02:54:26 GMT

well, on the subject of Fusion-IO, they had a paper at Flash Memory Summit, arguing that given main memory is mostly used a disk cache, it would be better implemented in NAND flash instead of DRAM.

My take is that true memory, ie, not the buffer cache, should be moved closer to the procesor. Then buffer cache, regardless of whether it is DRAM or Flash, becomes block storage instead of byte addressable.

re: New Seagate SSD and Hard Disks

Greg Linwood — Thu, 17 Mar 2011 19:34:40 GMT

I haven't seen the paper but maybe by "better" they mean "more"? because you can certainly get a lot more memory closer to the processor through flash than regular memory - eg, Fusion-io offers 5TB on a single PCIE presently.

re: New Seagate SSD and Hard Disks

Tom — Thu, 17 Mar 2011 20:40:02 GMT

Joe, I like you balanced approach, you cover all vendors and not just Fusion-IO like other reviewers do.

Keep up the good work, I real all your blogs

re: New Seagate SSD and Hard Disks

Greg Linwood — Thu, 17 Mar 2011 21:07:22 GMT

Tom - I agree its good to get a balanced article covering all vendors, which is why I asked why he left out Fusion-io :)

re: New Seagate SSD and Hard Disks

jchang — Thu, 17 Mar 2011 22:34:41 GMT

Greg, I meant bring memory really really close. Lets revisit. Most of memory today is used for caching. Only a small amount is used for program code and "data structures" for managing the program. So the object is not to get more "memory", but to get memory closer to the processor core than it is today, even if it means giving up memory size.

The capacity given up, would be implemented as block access structures at comparable latency, or even a little more.

So by bring memory closer to the processor, what I am really thinking is to have the memory on the processor package itself. The Intel idea is to mount the DRAM chip directly on top of the processor die. The connection is with thru connections, meaning the path between memory and processor would be many thousands of bits.

re: New Seagate SSD and Hard Disks

anonymous — Mon, 28 Mar 2011 23:21:25 GMT

Greg Lets revisit:

http://www.theregister.co.uk/2011/02/25/intel_westmere_ex_sandy_bridge_ep_xeons/page3.html

re: New Seagate SSD and Hard Disks

jchang — Tue, 29 Mar 2011 01:33:33 GMT

What I meant is described in Figure 7 below

http://www.realworldtech.com/page.cfm?ArticleID=RWT050207213241&p=4

re: New Seagate SSD and Hard Disks

Joe User — Tue, 17 May 2011 18:43:58 GMT

ALL FLASH EMC?

http://www.theregister.co.uk/2011/05/16/all-flash-arrays/