DS4800 intermix FC/SATA

[groener]

Hi, I have a question about intermixing FC/SATA in a DS4800. I would like to have 3 EXP810 drawers with RAID 5 arrays striping down through the drawers. Is it possible with the intermix feature, to say, have 3- 4Gbit FC arrays on the left side of the drawers (striping down, of course) and have 3 SATA arrays on the right side of the drawers, doing the same?

Is this what the intermix feature does for you? Or does it simply allow SATA and FC, in their own respective drawers to live together on the DS4800 controller?

Thanks,

Chad Groen
Good Samaritan Society

 

[gyuzik]

Chad,

The FC/SATA intermix feature set allows your to have SATA and FC enclosures existing together on the came DS4800... not in the same shelf.

Plus, with only 3 drawers... you would be limited to 3 disk arrays is you wanted enclosure redundancy. That means you will be losing 1/3 the useable space for each array which is not very cost effective.

 

[groener]

That's what I kind of thought. The IBM sales manuals and redbooks were kind of fuzzy about the feature. I definitely wouldn't want that short of arrays wasting a third of my array space in parity.....it was more of a simplified example of what I was trying to achieve.

Any thoughts on "enclosure protection"? Right now my arrays are horizontal. Are they in any real danger leaving them that way? Is vertical arrays of 5-8 drives the last step of redundancy for those who have the luxury to afford it?

Thanks again! Your comments are sincerely appreciated.

 

[gyuzik]

Well we just migrated to a vertical array structure, but it is overkill. We went that way because we have the requirement for 8+ 810 enclosures... but keep in mind that enclosure don't fail, components do! and that being said the enclosures are very redundant and you have a much greater chance of suffering a double disk failure on an array than a enclosure failure.

That being said IBM is working on a RAID 6 option to rectify that (2 disk parity), but until then I wouldn't worry about enclosure failures.

 

[krankin]

Important Update
-----------------------

As of DS4800 firmware 9.23, you can intermix FC and SATA in the same tray. That feature came out around April/May 2007. The real shame is that Sun was offering it in the 6540 (their version of the Engenio 6998) as of August 2006.

Mind you, there were probably some bugs if IBM didn't release it for that long.

So now the answer would be, yes, you can do that with a DS4800.

My real question is what sort of streaming performance people are getting with SATA on DS4800's. Anyone?

 

[djchopps0013]

Read my post on ba stg and migration taking there time. We are not getting the best performance despite it being IBM vs Hp in this thread. They are great for online storage just not as primary disks for TSM. Just what I have seen so far and the HP EVA is supposed to be the performer out of the bunch as far as FATA and SATA.

 

[groener]

Thanks to everyone for your help!

DJChopps0013....I read your other thread. I haven't personally measured my SATA yet, but thinking about what I migrate each night and I would estimate my IBM Storage to do about the same rate....unfortunately. :-( (DS4100 for stg pools)

We'll see if the DS4800 does any better. Still setting that up. IBM calls those SATA drives "4Gbit", where they call the DS4100 "2Gbit".

 

[djchopps0013]

Yeah I would definitely want to see what type of performance your getting on your end. I have no doubt the system were using has the capability to perform higher than it is, its just a matter of the right configuration. I am about this close to riding myself of HPUX and going with AIX or SUSE Linux.

Yeah if you go 4GB you should see better performance. We have 4gb hba's and the HP EVA is 4gb but our fabric is at 2gb so my hands are tied at this point.

 

[groener]

the results (with more to come)

10 GB from DS4800 2Gbit FC (5-300GB drives in RAID5)

to

DS4100 2Gbit SATA (10 250GB drives in RAID5)

90 GB an hour. I understand that there is the write penalty to take into effect, but still, not stellar. Sometime this week, I plan on doing some more "LUN shuffling" in AIX and will go the other way to demonstrate SATA read performance. I'll let you know.

BTW.....this is being done with 2 4Gbit HBA's on a 4Gbit fabric.

 

[chuckzul]

As a former LSI employee (technical engineer) of almost 10 years, don't waste your time with the intermix feature. It is more full of bugs than a spring picnic.

 

[cheekmp]

Chuckzul,

Would/could you elaborate? Do you mean that using the intermix in general -or- do you just mean mixing FC & SATA in a single shelf?

I'm using intermix with dedicated FC and SATA shelves on my DS4800. I had no plans to mix FC & SATA in a shelf, but it could be an option in the future.

Matt