More notes on the 8 IDE drive raid5 system I built, and the 3ware controller.

Edwin Hakkennes wrote:

May I ask how these ide-ports and the attatched disks show up under Redhat 6.2? Are they just standard ATA33 or ATA66 controllers which can be used in software raid? Or is only the sum of the attatched disks usable as one scsi disk?
The 3-ware site doesn't mention anything like this. Did you need any quirks
to get this running?
The 3ware controller is supported in the latest 2.2.X kernels. I used 2.2.15pre17. It is listed with the scsi modules and indeed, that is how the drives show up. In my case, I had an 9.1GB LVD drive on a tekram dc390u2 controller as my system drive (sda) so the four Maxtor DMA66 drives became sdb - sde. I didn't use 3ware bios or setup at all. 3ware expects you to use the controller as advertised - with their setup software to create a raid0, raid1 or raid1-0 array. I haven't tried that yet. I just wanted a lot of fast dma66 controllers in a single slot. I figured out how to address the individual drives, which as you can see, was pretty straight forward, and let the linux software handle the raid.

3ware doesn't mention anything like this, because it is news to them. They have no experience using their boards with software raid or raid5. Unfortunatedly, their boards are somewhat pricey, reflecting I suppose, there status as raid controllers, as opposed to UDMA66 controllers. At Linux Beach we have just become dealers for 3ware and can offer these boards at slightly less than the 3ware prices:

 QTY       ITEM NO.             DESCRIPTION                                                     PRICE
 ----------------------------------------------------------------------------------------------
RAID-3W5200L     3WARE ESCALADE 2PORT IDE RAID CONTROLLER            $119.00
RAID-3W5400L     3WARE ESCALADE 4PORT IDE RAID CONTROLLER            $219.00
RAID-3W5800L     3WARE ESCALADE 8PORT IDE RAID CONTROLLER            $419.00

So my question basically is: Could you send me the output of
cat /proc/pci
cat /proc/partitions
cat /proc/mdstat
ls -laR /proc/ide
This system currently a production server at my client's site so I don't have easy access to it. So I can't send you the proc outputs you requested. However they have promised to let me have it for awhile at sometime in the future for futher benchmarking and tuning. Hopefully I can get it then. Here is the raidtab:

/etc/raidtab

 raiddev /dev/md0
           raid-level              5
           nr-raid-disks           8
           nr-spare-disks          0
           persistent-superblock   1
           chunk-size              128
           parity-algorithm        left-symmetric

           device                  /dev/hda1
           raid-disk               0
           device                  /dev/hde1
           raid-disk               1
           device                  /dev/hdc1
           raid-disk               2
           device                  /dev/hdg1
           raid-disk               3
           device                  /dev/sdb1
           raid-disk               4
           device                  /dev/sdc1
           raid-disk               5
           device                  /dev/sdd1
           raid-disk               6
           device                  /dev/sde1
           raid-disk               7
 

Benno Senoner <[EMAIL PROTECTED]> wrote:

I went to the 3WARE site.
That is http://www.3ware.com
really nice the 8 IDE channel version and cheap too.
:-)

I noticed that they do not support UDMA/66. (at least the PDF says so).
On second look, this is correct. I know they used UDMA66 drives in their benchmarks:
http://3ware.com/products/3wareEscaladePerformanceAnalysis_kc.pdf
and recommend UDMA66 drives for best preformance.
Do you think that the impact is negligible when there is only one drive per chanel ?(At least I think that there are not that many EIDE disks which can sustain 
33MB/sec all the time). The load (in terms of bandwidth) generated on the bus/CPU by multiple (8) disks is quite high IMHO, therefore 66MB/sec * 8 (even if 
every drive would be able to deliver that kind of bandwidth) , would likely saturate your mobo/CPU, shifting the bottleneck from the disks to the memory/CPU 
subsystem.


The controller ships with single drive 80 wire cables, and the numbers I got were equivalent to those I got from the other DMA66 controllers running master only.
 

BTW, do you need a 2.3.x to work with these 3WARE monsters ? Or are there patches backported to 2.2.x floating around ?
I know it's in 2.2.15pre14 and above and modules are available at the 3ware site for RH6.1, RH6.2 and Suse 6.3.

TTFN

Clay J. Claiborne, Jr., President

Cosmos Engineering Company
1550 South Dunsmuir Ave.
Los Angeles, CA 90019

(323) 930-2540   (323) 930-1393 Fax

http:www.CosmosEng.com

Email: [EMAIL PROTECTED]
 

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