[dundee] ESATA Linux Support

[Lee Hughes]

I've not used any esata, I *presume* it's looks like a normal sata device, and should use normal sata drivers. I doubt esata uses a different protocol or device driver than normal sata,.
Why would it,  the the cable run's 'outside' of your machine. ..
(and probably has about 17 different connectors(!) I think..... i may be wrong!!  I'm sure
any multiplexing that's going on, is done in hardware (i.e 1 cable, 4 disks)

If things are doom and gloomy on the esata , don't rule out using aoe over gigabit ethernet, give you flexible storage over the network, and combine that with some clever drdb -ing you can add as much fault tollerance as you want.

http://mike.neir.org/weblog/619 is interesting.

You don't exactly say what your going to use the storage for, gigabit ethernet cards and switches are cheap, and you can bond (if your using linux) gigabit together, some people I've heard have got over 300mb/s of read/write performance using this method, and striping aoe over different  disk and systems. using drdb would add a layer of fault tollerance to the gig.
If you go this route use PCIE gigabit adapters, not those made in pci format, they are cheaper, but you'll only ever get around half the speed that gigabit ethernet can go, as they just eat all the pci bus bandwidth....








iscsi is interesting, but I just get more success with aoe at the moment in terms of raw performance......

when you get it out of your head that storage is no longer attached to system, but just
out there on the network somewhere, you can start doing some very clever things.

you don't need to bring a server down to add sata storage, just configure it somewhere 
else and import it. Hotswap sata driver bays are nice, but expensive.

Replicate your storage array somewhere else, may to anothe building, now your data
is safe from falling asteriods.

 Using loopback devices, 'partitions' can be simple linux files (all beit large), thus you can
do clever thing with cow's .. mooooo.


here some links....check em..

http://www.drbd.org/

http://www.linuxjournal.com/article/8149

http://en.wikipedia.org/wiki/ATA_over_Ethernet

http://www.mjmwired.net/kernel/Documentation/networking/bonding.txt



A guide I wrote on using aoe vblade's with cow's. 

http://www.etherboot.org/wiki/appnotes/cow

on the other hand, if you want to get a lot of storage, and want support etc don't forget these people....

http://www.coraid.com/

http://www.coraid.com/PRODUCTS/SR2421

24 Terrabytes anyone, almost enough space to store azmodie 'film' collection ;-).

Cheers,
Lee

--- On Mon, 9/3/09, Simon Wells <swells at computing.dundee.ac.uk> wrote:
From: Simon Wells <swells at computing.dundee.ac.uk>
Subject: [dundee] ESATA Linux Support
To: "Tayside Linux User Group" <dundee at lists.lug.org.uk>
Cc: "Simon Wells" <swells at computing.dundee.ac.uk>
Date: Monday, 9 March, 2009, 6:56 PM

Does anybody have any experience of using eSATA with Linux?

I have been looking at something like the following:
http://www.amazon.co.uk/EdgeStore-DAS801T-Bay-eSATA-Enclosure/dp/B001H54JWW/ref=cm_cr_pr_sims_t

My plan would be to organise it as two separate JBOD arrays, using LVM, and
connected via eSATA. The two arrays will give me some measure of redundancy and
will make backing up my data much simpler. There is also a second remote server
that holds backups and very important data is also archived to DVD.

At the moment I am using a whole pile of separate external USB drives and want
to simplify the system by getting all of the drives into a single unit. Am I
missing anything? I have not used eSATA with Linux myself and would like to know
if there are any gotchas or things that I should be aware of.

Thanks,
Simon

Dr. Simon Wells
=============

E-mail: 	swells at computing.dundee.ac.uk
IM: 		sw3lls at yahoo.co.uk
Mail: 	School of Computing,
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		University of Dundee,
		Dundee, DD1 4HN.
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Fax:		+44 (0)1382 385 509 (FAO: Simon Wells)




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