High End SSD RAID help

[pennyfan87]

Hi dudes.

I'm putting together an I/O intensive server for a client. The guy is willing to spend for the best. I need some input from you guys as to the RAID situation.

The variables to play with are as follows:

X25-m (80gb, 2G) or X25-e (64gb)?

RAID 10 or RAID 5? We need 200GB of space.

What (PCIe x16/8) controller do you recommend? Will any controller be able to handle the RAID 5 calculations? I hear Areca and Adaptec are good. Any preferences? Any others I should think about? How much RAM should the controller have?


So far I'm leaning towards 6x X25-m (comparable performance to X25-e, better performance for the money) in RAID 10 (less stress on controller) and a mediocre controller (only a RAID 10, after all)

A coworker is convinced that RAID 5 with 5x X-25e and a top controller is the way to go, but I'm not convinced.

About the workload of the server: database access for many LAN clients. Its custom software so its kind of hard for me to know about the data patterns.

Yeah, I'm a noob at this stuff. Recommended reading is appreciated.


Thanks!

 

[pennyfan87]

I'm leaning towards the Adaptec 5805 (http://www.newegg.com/Product/...?Item=N82E16816103099)

It only has 512mb RAM. Will more help?

 

[pennyfan87]

Okay, it seems you guys aren't so fully versed in the enterprise side of things. Its okay. I'm not either.

Any forums you know about where I can ask?

inb4 4chan

 

[Cr0nJ0b]

first, slow down...

Now...back to your question. You want a fast array for high IO. ssd will give you lots of IO. I think that the numbers I saw were like 14MB/s for rand write and 230MB/s for seq read.

So what are you planning to do with this? Lots of seq reads? rand reads? rand writes?

what is the application?

what is the OS?

what is your budget?

What is your tolerance for faults? Can the system be down for hours? can you stand to lose some or all of the data? What are production hours for you? 7x24? Are you planning to use this as a revenue source like a etailer web site?

All of these questions will let us know whether you need RAID0, RAID1, RAID10, RAID5 or RAID6.

Without all of that I can take some guesses...

I'm partial to Areca, but according to Tom's AMCC has a really fast controller link

I haven't seen any RAID tests that have been done with SSD, but i would suspect that at some point you saturate a PCI bus or SATA chipset before you top out a RAID stripe.

Raid 5 will be much slower, but will give you some degree of fault tolerance...and the cost of only one additional drive...but you still need to back things up.

 

[pennyfan87]

Thanks for the help dude.

Here's some more info:

Application: Proprietary Visual FoxPro database accessed by 30 workstations over LAN. Heavy on Rand Read and Writes

OS: Win Server 08

Budget: Less than $5,000, but I'd rather save than splurge for diminishing returns.

Can't stand to lose data.

System should be up 9-5, 7 days a week. If the system is down, employees can't do their work.


Anything else you need?

 

[Cr0nJ0b]

OK, that helps.

I'm thinking with 30 WS over a LAN, you would probably be fine with a mirrored pair of ssds for the database. you need to look at the expected random IO that these people will generate divide that by the IO of a single flash drive.

I think a single Intel 64GB ssd can do like 7,000 IOP/s in the small block range. so figure that every user will get around 200 IO/s sustained. This seems like a lot of IO for regular users. If they are people and not worker processes, then I would say they would be happy with that kind of IO with a 2ms response time.

You would definitely want to mirror the drives for availability, though ssd drives have a pretty good reliability factor since there is no spinning disks.

add to that a 1TB drive (they are cheap) and have a backup process take a nightly full backup.

I'm assuming that 64GB would be enough capacity for the DB. if not, buy a bigger ssd. You don't necessarily have to go with intel. The IO performance will be similar. But keep in mind the performance aging of ssd drives. prepare to TRIM them or do some other clean up on a regular basis.

If the DB is small, you will probably also want to pay for a service like mozy.com and backup everything to an offsite server in case your Data center gets hit by a stray laser or something.

 

[pennyfan87]

Is the X25-E worth the price difference over the x25-M?

Thanks.

 

[Emulex]

yes in a server it is. however the next gen x25-e with battery backup will be far superior.

you should buy into a product like fusionio; they can do raid and xfer over pci/express bus. there's a few others out there too.

i'm not sure there are any trim compatible hardware raid controllers. let me know if you find one though. reputable is something like the hp ccissm which has pretty much used the same driver layer for the last 10 years of raid controller. vmware hcl certified would be nice too.