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Xiotech Unveils Disruptive Storage Technology
Lxy writes "After Xiotech purchased Seagate's Advanced Storage Architecture division, rumors circulated around what they were planning to do with their next-generation SAN. Today at Storage Network World, Xiotech answered the question. The result is quite impressive, a SAN that can practically heal itself, as well as prevent common failures. There's already hype in the media, with much more to come. The official announcement is on Xiotech's site."
Just to clarify, SANs generally aren't used primarily for backups - they're just used for server storage to have a centralized and more thoroughly redundant setup than local disks (i.e. put your 40TB document repository on the SAN and connect it over fiber to the server, or have your server boot off the SAN instead of local disks, etc). They're treated like local disks by the OS, but are in a different location connected via fiber or nowadays via iscsi.
While you can sometimes do some neat tricks with backups and a good SAN infrastructure, it's by no means its primary purpose in life.
well, RTFA. For mod points, it's disruptive because it runs Linux!
The second article describes this very well. One big extra is that this system can perform all of the standard drive-repair operations that typically only OEMs can. This helps to keep you from replacing drives that aren't bad, but had a hiccup.
It's also not just two drives in an ISE, but more like 10-20 (3.5" and 2.5" respectively) with a bunch of Linux software to give each ISE a pretty robust feature-set in itself. Then they also up the block size to 520 bytes, leaving space for data validity checks in order to keep the silent corruption problem from sneaking into the system.
In the end, it's probably not wholly revolutionary. It does seem like an evolutionary jump though; with great performance, great feature set, and a very well thought out system that brings new technology and ideas to bear.
Let's see now... ah! I've got it. Here's an exact link for you: http://www.google.com/search?hl=en&q=san
You could use it for that, but thats not the main use.
It *is* a network like your ethernet network (with switches, adaptors, etc), but usually its a FC (fibre channel) rather than ethernet. You use a SAN to put your servers disks in another box to the server.
But why would I do that? heat, consolidation, redundancy.
A typical setup is to have a few 1u or 2u (rack heights are measured in u, which iirc is about 2") servers attached to a 3u storage controller.
This is a box with lots (typically 14 in a 3u box) of drives. There will be a small computer controller in there too as well as some raid chips.
Typically in a 14 drive box you might configure it as a pair of 5+1 raid 5 arrays and a couple of hot spares (5+1 means 5 drives of data and one parity drive). Effectively your 6 drives appear as one with 5x the capacity of 1 of the component drives. You can survive the loss of one drive without losing data. If you do have a drive go offline, the controller should transparantly start rebuilding the failed disk on one of the hot spares (and presumably raise a note via email or snmp that it needs a new disk).
The controller is then configured to present these arrays (called volumes in storage speak) to specific servers (called hosts).
The host will see each array as a single drive (/dev/sdX) that it uses as per normal, oblivious to the fact that its in a different box.
Now to revisit the why we do this:
1. heat - by putting all the hot bits (drives) together we can concentrate where the cooling goes
2. reliability - any server using the above setup can have a disk fail and it simply won't notice. With the hot spare setup, you can potentially lose several drives between maintainance (as long as they don't happen at once).
3. cost - you can buy bigger drives, then partition your array into smaller volumes (just like you partition your desktop machine's drive) and give different chunks to different hosts, reducing per GB cost (which when you are potentially talking about tera and peta bytes worth of disk space is rather important).
as for what these guys are up to, I've not had a chance to look yet. I might post back.
"Success is based on knowing how far to go in going too far"