3ware 9500s - RAID 5 SLOOOOW SPEEDS. Help!

Hi all,

Need some help with slow raid 5 performance on my 3ware 9500s controller.

Currently only getting between 3-15MB (writing between arrays) 10-25MB's (writing from MB attached HD to either array)

This seems very slow. Is there anything I can do to improve read/write speed?

1x RAID-5 (3x 750gb Samsung/Seagate -64b stripe)
1x RAID-5 (4x 1000gb Western Digital 256b stripe)

win7 64bit
6gb ram
Gigabyte ga-x58a-ud3r
i7 920
card is plugged into PCI slot (as MB doesnt have a pci-x slot)

3ware 9500s-12
firmware: fe9x2.06.00.009
driver: 3.00.04.070

Seems like typical 3ware to me. They are really slow with parity raid. On a 3ware 9650se-8i I got up to around 200 megabytes/sec writes for a very short period of time (a couple seconds) and then it would drop to ~ 20 megabytes/sec. If I wrote 0's to the entire array the average speed was maybe 25 megabytes/sec throughout the entire array.

Do you have the BB unit? If not write cache may be off by default. For any hope of performance you need cache to be on. A HW card or even software array with cache off will not perform well at all. They need cache to avoid the need to read each stripe before writing.

As for your numbers that is awful. I get over 200MB/s writes and 300+ MB/s reads with linux software raid on 4 year old desktop systems.

card is plugged into PCI slot

Click to expand...

That is going top limit you to around 100MB/s (slower than a single drive of today) but at this point I guess you will be ecstatic if you can get single drive performance.

Lol - yeah Id love single drive performance
How risky is running without a BBU and having write cache turned on? If something bad happened would I lose all of the data on the array or just the current write (stored in the cache)

Cheers

All stripes that have not been written back to disk would be lost if you had an instant power off. Not a problem if you had a UPS. In either case the controller should flush the dirty (unwritten data) cache in a minute or so. As a result it will not hurt old data. It can cause filesystem corruption if the filesystem structure was part of what was not flushed when the power was lost.

At work on the one windows workstation I have a raid (my other 20 to 30 TB is on linux software raid). I do not have a BBU with my 3ware controller but I forced the cache on using their web page setup. In 3+ years of this I have not lost any data due to this. I do have a UPS attached to the system however.

What is happening to your card is that it sees that you do not have a backup battery supply. It automatically defaults to the very slow read and write speeds because of it to ensure no loss of data in case of a power failure. I very strongly recommend that you have the battery backup unit that can attach to the card or a UPS attached to the computer. You paid a lot of money for the card and drives so you do really need that battery backup to prevent the card from requiring you to do a rebuild of the Raid system if there is an interruption of power to it or a blue screen reboot. But on the other hand you can override the settings in your web based browser. Beware though that if you do not have a battery backup, you may be required to replace a dropped drive in your Raid with a new drive and not allow you to just do a rebuild.

Log in as Management and click the management tab. Under Unit Policies change the following setting to:
Write Cache: checked
Read Cache: Intelligent
Auto Verify: checked
Queuing: checked
StorSave: Performance
It will come up with several warnings that it does not see a battery backup. Override at your own peril to increase your speeds.

what kind of performance increase does write caching provide? are there any other options for increasing write speeds?

Also, go to 3Ware's site and update your Firmware and Driver (it is not current) before you do the above changes.

You should be at 80 to 100 MB/s and there are no other options with this older card.

Thanks rembrandt! Any particular order or "best practice" in terms of updating firmware and drivers?

Not really. I reboot just after I do an update. It is not necessary but gives me peace of mind.

write cache and auto verify turned on - out to pick up a UPS.
currently getting 30-60MB write speeds but also shopping around for an upgrade.
any thoughts on the HP smart array p400? would this be worth getting? Also what are the chances of it running on win 7 64bit?