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SmartArray6400 2TB Limitation

 
Haggisnneeps2
Frequent Advisor

SmartArray6400 2TB Limitation

I have 2x MSA30s with 28 300GB drives attched to a DL380 G5 with Server 2K3 R2 SP2 via a SmartArray6400 and am disappointed to find out that there is an upper limit of 2TB per logical drive (and that if i connect these to a MSA1000 i will be limited to 2TB LUNs too). If, then, these are the limits imposed upon me :-( i wondered about using spanned volumes to create a larger volume which has raised a number of questions i cant find answers to.
1)HP recommends that for the amount of data we are storing we should be using approx 60 (yes sixty) disks in an array to get the sort of read/seek/cache I/O we desire.This is impossible since 7x 300 GB disks reaches the upper limit of the 2TB limitation. How can i do this?
2)If i create 4 logical drives RAID6 maxed out at 1430488MB and then span these in Windows, will 1 disk failure still fail the entire spanned volume?
3)in the scenario above, will software striping (creating a striped volume) add to performance or degrade it?
4) What is the MOST BEST HIGHEST performance it is possible to achieve reading from/ writing to arrays of this size (millions of small files and folders)
5) Will it be possible for me to take an MSA1000 and add 2x MSA30 trays to it and safely and effectively utilise all 42 300GB drives in any kind of supported configuration?

Thanks
8 REPLIES 8
James Muell
Valued Contributor

Re: SmartArray6400 2TB Limitation

You will have far, far better performance using straight SCSI connected disks, and a U320 based array controller (i forget the speed of the 6400).
Also, have you thought of setting up Windows DFS to get disk space you need? I haven't used it you can get larger space with it.
The MSA1000 controllers have an i/o limitation of 160mb/p/sec. If your running Fw v7.00 you could assign luns to the different controllers to optimize thru-put. Version 7.00 would probably do this automatically as it monitors lun i/o and shifts luns accordingly.
But for what you are attempting I would not think the MSA a good fit. We have dozens of MSAs in use but none really needing optimum performance.

gl
Haggisnneeps2
Frequent Advisor

Re: SmartArray6400 2TB Limitation

THe reason we need such optimal performance is because this is our file and print server and and we back up around 2 TB per LUN and it takes 4 days to do it. If i could create 1 big logical volume i would get the benefit of utilising all 42 drives for better read speed (at the expense of reduced redundancy / fault tolerance / data integrity)

The gain though would far outweigh the penalties as i could do a full backup and or restore more quickly

My problem, really, is DR versus Backup. At the moment we backup this data very slowly and DR is out of the question due to the timescales involved in recovering this volume of data. On the other hand, if i sacrifice the integrity and go for performance then i could reasonably do DR and backups fairly quickly but the chance of HAVING to do DR increases (eg currently data is on RAID6 logical drives but i could double read/write speed by using raid 0 but losing 1 drive would require DR or i could increase read/write by using raid5 on a bigger logical drive using more drives)

Unfortunately our data is critical so my choices are limited to RAID6 on 7 Ultra320 15K drives on a 2TB LUN via FC unless there's some way to increase LUN or logical drive size past 2TB
James Muell
Valued Contributor

Re: SmartArray6400 2TB Limitation

You would have to use 3rd party product like verita$ to do the spanning.
SCSI would probably still be faster than the MSA. Did you try a 14 drive Raid6 w/2tb lun?
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Haggisnneeps2
Frequent Advisor

Re: SmartArray6400 2TB Limitation

I cant at the moment. The MSA1000 is the live environment. My test server is a DL380 G4 connected to 2 MSA30s via SA6400EM (ultra320) dual channel (4 slots 2x a&b not sure what the best config is here...)

In a couple of weeks i'm going to connect these 2 MSA30s to the MSA1000 and hoped to re organise the data into 1 big logical volume. I suppose if i can even get all 42 drives configured as RAID6 then each 2TB LUN will be 1/6th of the 12.6 TB spread across all 42 drives - is this correct?
James Muell
Valued Contributor

Re: SmartArray6400 2TB Limitation

Yes, that would be correct. I'd try that too if i were in your shoes. report back!
Haggisnneeps2
Frequent Advisor

Re: SmartArray6400 2TB Limitation

Will do - it will be 3 weeks or so though til i do the change

So is my MSA1000 restricted to 160 Mb/sec even though it has 2 controllers (active/passive and still at firmware version 4.48 with EMU 1.86) and 2Gb HBAs in it? (not that it matters as the read speed is ridiculously low
James Muell
Valued Contributor

Re: SmartArray6400 2TB Limitation

you would get 160 out of both controllers if your running MSA firmware version 7.00 and have the correct HBA driver & fw and multipathing sfwr.
Haggisnneeps2
Frequent Advisor

Re: SmartArray6400 2TB Limitation

Now here's the question.... IF i create an array across all 42 drives, then split it into 6x 2TB chunks, that means that each individual drive has to service 6 different logical drives. So is this really a performance gain over having 7 drives dedicated to each logical drive?