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can these enclosures be populated with SATA or SAS drives purchased elsewhere?

recently Dell has made custom size slots on their PE T710 servers on which you could only place drives purchased from Dell !

is there an opensource way of doing ATA over ethernet? Coraid seems to do some flashing on HBAs? SAN HBA's http://www.coraid.com/products host_bus_adapters_hba?

are not they proprietary?

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sorry to ask, but what has AoE to do with SATA and SAS caddies? –  Hubert Kario Oct 10 '10 at 8:55
    
AoE is en.wikipedia.org/wiki/ATA_over_Ethernet - really good way to get blistering performance without the bulky iscsi stack penalty. –  Khushil Oct 10 '10 at 9:38

2 Answers 2

up vote 3 down vote accepted

I have several Coraid boxes, working flawlessly for several years. They're Supermicro chasis and mainboards, very good quality. The Coraid 'magic' comes in a flash IDE module, containing a Plan9 OS and their AoE 'target' software. The 'initiator' has been for some years in Linux kernel, but usually it's better to compile your own module to get the latest one.

They don't seem to be doing any custom HD firmware, and do support any brand. Of course, now it's saner to recommend 'enterprise SATA' disks, that have better MTBF, bigger buffers and other goodies over 'cosumer SATA'. Or, you can say that it's consumer disks getting worse and not 'enterprise' ones getting better.

There are several implementations of AoE targets; but the basic reference code is single tasking and doesn't perform well with multiple hosts. Other ones are much better and compare favorably with iSCSI targets. In the Xen user's list some users have reported great performance and scaling well to 10GE.

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hi, so do you mean "#1:it is feasible to plug in any enterprise SATA in a Coraid box, #2 magic is in the OS not firmware and #3 opensource implementations of AOE targets are single tasking and do not scale well" please correct me if required, thx –  John-ZFS Oct 11 '10 at 1:08
    
what about HBA's coraid.com/products host_bus_adapters_hba? are not they proprietary? –  John-ZFS Oct 11 '10 at 2:06
    
Wow.. Plan 9! That's interesting –  Tom O'Connor Oct 11 '10 at 9:43
    
@maruti: #1 yes, #2 magic is in 'box' firmware (small IDE flash), not HD firmware, #3 all (non-firmware) AoE targets i've seen are OSS, some very good, some not so. haven't heavily tested myself, though. –  Javier Oct 11 '10 at 14:39
    
@maruti. haven't used the HBAs; they seem to be embedded implementation of the AoE initiator. i guess it's proprietary, at least, that makes it easier to certify for VMWare. useless for me, since Linux already includes it in the kernel. –  Javier Oct 11 '10 at 14:42

So here's how it works:

Storage vendors sell array controllers, which are often "tuned" or locked to only work with a certain brand/firmware version of disk. The basic reason being, that they're selling support (and making a massive stack of money on that, and the disk sales.) If you stick in any old disks, there's no way they can sensibly follow the support side of things, and there may be seriously unpredictable results.

SAN vendors don't like unpredictable results, it looks bad for them. There'd be no way to stop the media (and that's who they're interested in) from saying "PQRST Storage went wrong causing massive data loss for XYZCorp", and not mentioning "Because they used uncertified disks".

See what I mean?

Basically, it's a lot easier and cost effective if you buy their disks, then you get their warranty, their support, and their coverage when it all goes to shit.

If you want to save money on disks, I think you're playing in the wrong pool. SAN storage is EXPENSIVE, and reliant on warranties, SLAs and support. If you don't want to pay for these, then you could build your own storage server, but you've only got yourself to blame when it all goes wrong.

With regards to your question about AoE, I googled, and came up with this https://help.ubuntu.com/community/ATAOverEthernet

Seems to do some of what you mentioned. I'm sure there are similar packages/tools available for other OSes. Not too sure on the Redmond bunch, though. That said, I've not used any of the linked materials, nor have I played with AoE, so YMMV.

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+1 Tom. I especially agree with the comments on uncertified disks. If something is important enough to need SAN level performance and reliability then its important enough not to undermine that by installing whatever was on sale this week at "crazy joe's place of hard drives - ask to see our special pricing on IBM deskstars for your SAN" –  RobM Oct 10 '10 at 10:59

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