RAID 0 setup with ssd's

[Deke09]

Hi,

I don't think my setup of RAID 0 with my 2 corsair CMFSSD-32D1's is working properly.

Using HD Tach I'm only getting avg read of 159.2mb/s it has 2 burst during the 62gb test that go up to 300 mb/s.

I have the 2 ssd's connected to sata port 0 and 1.

I have Segate 250gb drive connected to sata port 4 and Sony optiarc DVD on sata port 5 as IDE

I think I don't have something setup right in my BIOS

Can anyone confirm this?

Thanks,
Deke

[wazza300]

Re: RAID 0 setup with ssd's

are you using intel or jmicron controllers/ports?

[Psycho101]

Re: RAID 0 setup with ssd's

Did either of your drives have an OS or data on them, ie were they used for a while, before you set up the aray? If so, and the use was heavy, or even not so heavy, then the usual degradation of performance from having no clean flash blocks left may be happening.

Those speeds certainly are slow. I would expect that for the 32GB version of that drive, RAID0 read should be ~400MB/s and write ~220-250MB/s (remember that the 32GB versions of that drive are a tad slower on writes due to there being physically less NAND IC's onboard.

In any case, What I would do personally is back up your data, image the array, disengage RAID and run either Sanitary Erase (needs to be run in Windows, or on the recovery console booted to with a 32bit Vista/Win 7 install CD) or my personal favorite is HDDErase version 3.3. When running HDDErase, you need to have the Intel SATA ports set to IDE mode and have Ports 0-3 Native mode disabled (ie run in legacy IDE). If you don't set this, HDDErase won't see your drives.

Both these programs will issue the ATA Security Erase command to all NAND flash blocks, causing the NAND to be reset to factory fresh. After this is complete, which should take no more than 1 minute for each drive, you can set the RAID array back up and re-image, or fresh install if you wish.

What stripe size are you using for the RAID aray? SSD's tend to work best with a 128K stripe size. Any lower than this really seems to dent performance. Also if using Vista or Windows 7 Do you have the Advanced Performance (Vista) or "Turn off write back cache buffer flushing" box checked? If not check it (in Device Manager > Disk Drives > Properties > Policies tab).

Just to confirm that the array really isn't up to speed could you please post a couple of screen shots. Download and run AS SSD and run the standard tests (not the file copy ones). Also Download and run ATTO, using the standard settings of a 0.5KB to 8192KB test range, Overlapped I/O and a Queue Depth of 4.

It would be a good idea to create a signature with your full system specs in it. As you say, it could be a BIOS issue or a SATA/RAID driver issue, and not knowing what mother board you have and what southbridge it has means I can't make specific suggestions.

I've included a couple of my own bench mark pics so you know exactly what to include from ATTO/AS SSD. If using Vista/Win 7 the Snipping Tool is great for imaging just a single window.

[Deke09]

Re: RAID 0 setup with ssd's

Ok I have some home work to do.

I have specs in signature.

Thanks for all the great info, I'll have to check all this out.

I'll return with pics and settings.

Thanks alot,
Deke

[Deke09]

Re: RAID 0 setup with ssd's

Hi Psycho101,

Maybe everything is ok, and I'm only seeing results from other ppl who have raid 0 but is not there boot drive like mine is. I'm using Vista 64bit

Here are some pics of things;







As for being able to change the stripe size I did not see that anywhere, all i saw was the allocation size of 64k and it was not editable, is this something that has to be done when the raid was created?

Anyways I'm going to be changing to windows 7 soon, and I want to make sure I get everything correct this time around if it's not.

Thanks,
Deke

[Psycho101]

Re: RAID 0 setup with ssd's

There's definitely some sort of problem. You should be seeing double the read and write performance that ATTO is showing you.

Intel on their ICH10R have a utility called Intel Matrix Storage Manager. Ran in Windows, this program allows another write back cache to be created and used seperate to Windows cache options. Does your motherboards RAID drivers have anything similar? Here is a pic of the IMSM program. Have a look and see if an AMD/Marvell or what ever brand of RAID controler your board has, has a similar function.




RAID stripe size is specified when you create an array in the RAID BIOS utility. 128K is optimal.

When you get your copy of Windows 7 I suggest doing the following:

Take the drives out of RAID (destroys the data). Run HDDErase 3.3 with the SATA controller set to Legay IDE mode. Perform a Secure Erase of both drives (not an enhanced secure erase). This will completely reset the NAND flash.

Now set up the array from scratch from within the RAID controllers setup utility, selecting a 128k stripe size. When this has been done (obviously you need to set RAID for the controller after using HDDErase to be able to do this) create a partition aligned to 128K. To do this, boot from the Win 7 CD and choose "Repair My Computer" rather than going the usual install route. At this point you need to point windows to your RAID drivers which should be on a floppy or USB stick. After they load you'll be at the "System recovery options" window.

Choose "Command Prompt". Now from the prompt, run Diskpart.

When diskpart has loaded, you first need to select the RAID array. To do this, first type "diskpart list" (without quotes). You will see a list of all drives connected to the PC. The RAID array will be easy to spot as a disc of around 60GB in size. Type "Select disk x" without quotes, x being the number of the raid array shown in the diskpart list. Diskpart will tell you "Disk x is now the selected disk".

Now to create a 128K aligned partition on the array, type "create partition primary align=128. To confirm it's success type "list partition" and you will see a breakdown of the partition you just created, shown as the full size of the array, and with a 128K alignment.

Finally, the partition needs to be set as active so that it's bootable. To do this simply type "active" and hit enter. You'll get a confirmation message for this action. Now type "exit" to close diskpart.

Reboot and run the OS installation as normal. Do not however, delete or alter the partition structure in any way during the install process. When Windows asks where you want to install to, simply point it in the direction of the RAW aligned partition and let Windows Quick Format it and start copying files.


If you still have performance issues, I strongly suggest contacting Corsair via their support forum and see what they suggest. If the board is set up perfectly, the RAID array is optimally configured and you have an optimal alignment then the issue may reside with the SSD's themselves.

Again, removing them from the array and testing them individually using AS SSD and ATTO may be a good idea. Perform a Secure Erase on each drive and Quick Format to NTFS, then run the benchmarks. You will need to either have a third HDD to install the OS to, or you can use one SSD as the OS and bench the other, then swap round.

For completeness, I've attached an ATTO bench of a single X32 drive. As you can see, the drive is almost about beating the performance you're getting from 2 in RAID 0:

[Deke09]

Re: RAID 0 setup with ssd's

Hi Psycho101,

Thanks for taking the time to answer my question. :)

I'm going to have to print your last reply for when I change over to windows 7, next week.

Thanks again Psycho101, you've been alot of help!
Deke

I'm going to start a new thread on another question about memory speed.

[Deke09]

Re: RAID 0 setup with ssd's

Did some research it appears that the SB750 Raid controller is slow, at least when this chip was first released, i'm currently running F5 Bios version, I could go up to F7, just wondering if the SB750 Raid has been improved yet?

Deke

[Psycho101]

Re: RAID 0 setup with ssd's

It depends if the BIOS includes any update for the RAID component of the AMD SB.

To completely troubleshoot your problem, I would do the following (if the system was mine):

• Backup any data on the array and take the array down (delete the drives from the array in the RAID config).
  
• Set Legacy IDE and run HDDErase on each disk seperately choosing option 1, Secure Erase.
  
• Flash Your BIOS to the latest version, then hit "Load Optimised defaults on first boot and restart.
  
• Enter the BIOS again and restore any settings needed. While here it is important to increase AMD SB750 voltage by 2-3 ticks. This can greatly help, and has proved valuable in many posts in many forums including Corsair and OCZ support.
  
• Now set up your RAID in the usual manner, choosing a 128K stripe size. This may be the maximum you can set. That's fine. You will see an improvement in performance over all other sizes by using 128K.
  
• Install Windows on the array and give it another go, this time using ATTO and also CrystalDiskMark. Remember that every time you bench you will impact performance. Over benching is a good way to effectively "clobber a SSD".

The AMD SB's in general don't perform as well as Intel ICH's etc, but manage performance much better than you are experiencing, even with a 64K stripe.

[Deke09]

Re: RAID 0 setup with ssd's

Set Legacy IDE and run HDDErase on each disk seperately choosing option 1, Secure Erase.

I didn't do this, I did use the Secure Erase from within the RAID BIOS Utility, should I do the HDDErase way?

Flash Your BIOS to the latest version, then hit "Load Optimised defaults on first boot and restart.

I will falsh to the highest to see if there is an improvement to the SB750 RAID Controller.

Enter the BIOS again and restore any settings needed. While here it is important to increase AMD SB750 voltage by 2-3 ticks.

Hmmm, why would I need to do this? I'm not over clocking?

Now set up your RAID in the usual manner, choosing a 128K stripe size. This may be the maximum you can set. That's fine. You will see an improvement in performance over all other sizes by using 128K.

I'm currently at 128K stripe, only have 2 choices 128 & 64.

Looking at your ATTO results of 2 32gb ssd's your around 275mb, I'm not to far off now.



I'll give it another go around next week, see if chaing to IDE and using HDDErase make s a difference, I'm looking at a difference of 25 to 30mb difference when comparing to yours.

Thanks,
Deke

[Psycho101]

Re: RAID 0 setup with ssd's

The banefit of increasing SB voltage is that SSD's have extremely high throughput. The AMD SB isn't very well tuned for SSD's and has to work its little arse off to maintain good throughput. In doing so, it in most cases comes up short on power. Adding SB voltage (just a small amount) has been known to help. It's also repeatable, ie if voltage is lowered again, performance drops, proving voltage makes a difference.

I will find a link to a good thread showing before and after with I think ATTO. The difference with more voltage is quite pronounced.

Definitely use HDDErase or as an alternative run the utulity "Secure Srase". This is a program downloaded similar to HDDErase (use HDDErase 3.3, if not working try 4.0) but SE needs a 32bit (must be 32 bit) Windows envoronment. The only way to run it without using a spare mechanical HDD to load Windows is to use the XP recovery console or the Vista/Win 7 Command Prompt option in the "Repair my Computer" menu, given to you when booting from the install media when Windows is already installed. The RAID utility writes garbage data as itssecure erase. The HDDErase and SE utilities both issue theactual ATA-SECURE_ERASE command, just flagging the block as completely clear. This is vital because "empty" for a SSD block is actually when the block is set to "1", the SE in a RAID BIOS will write a "0".

Keep an eye on your Writes. This is what concerns me. They are currently slower than a single X32/30GB Vertex/32GB Runcore (all the same hardware inside) should be.

Without doing a HDDErase/SE secure erase, the results won't show the true extent of how much they helped, but if you go into the BIOS now and set SB Voltage upward three ticks, then install and use RAIDxpert following the instructions to enable the RX disk cache, you will hopefully see an improvement in those sequential writes. The voltage tweak is well worth it, it's one of those "miracle settings" that can instantly fix some problems. If three ticks won't show a difference you can safely add another two ticks. AMD SB voltage is adjusted in tiny increments on most boards. If unsure, see how much one tick raises it and post here so I can advise you further to the safe limit.

I would also be interested to see what CrystalDiskMark gives for speeds as it also tests random performance. If random performance is good (4K read/write in a butterfly pattern, ATTO is only sequential) then any slow sequential write won't effect performance much, except in file copying.

I will post again when I find the thread concerning SB Voltage. It's quite the magic setting for AMD systems, even with one SSD sometimes.