Hello

Hard drives and SSDs cannot write at 3500 or 6000 MB/s. The speeds you are seeing are cache write speeds. If you are getting significantly faster cache write speeds on one controller then you should look at the memory settings.

Write-back cache is obviously enabled on both controllers. Check to make sure that disk cache is enabled on the slower controller. Enabling disk cache will improve performance, but since it is not battery backed it could lead to data loss/corruption in the event of sudden loss of power.

Any speeds you achieve above around 400-500MB/s is achieved via cache. Check to make sure that both controllers have the same amount of memory/cache and have the same memory/cache settings.

Thanks

Daniel-

Thank you for replying.  I attached screen shots from OMSA regarding controller and virtual disk settings.  

You can see the cache mode and the size of the cache (1024 MB) is the same.  Where else are there settings (and what settings)? 

I would appreciate if you could be more specific - I have spent much time looking at this problem and when you say "memory/cache settings" I think I have looked at them all.

Again, the speed moves with the controller board itself - unrelated to the disks or the server.

Thank you

I would appreciate if you could be more specific - I have spent much time looking at this problem and when you say "memory/cache settings" I think I have looked at them all.

Both cache policies are enabled.

Again, the speed moves with the controller board itself - unrelated to the disks or the server.

That is unlikely. The system configurations are not identical as you have stated. The RAID arrays are different, and they are likely using different disks. You cannot compare performance across different hardware or RAID configurations expecting them to be the same.

Thanks

Daniel-

Please accept the information I provided.  The speed does move with the controller.  Of course there is minor variation across systems due to the disk size, etc but I am asking about almost 100% speed difference.

I found this that is consistent with the fact that it moves with the controller:

Result of Megacli -AdpAllInfo -aALL

Slower H710p

Host Interface : PCIE

Link Speed : 2

Faster H710p

Host Interface : PCIE

Link Speed : 3

This relates to the negotiated link speed on the PCIe bus.  It looks like the slower board is stuck at 2nd generation PCIe which is about half the speed of 3rd Generation PCIe.

Evidently there is a configuration option in the H710(p) that enables 3rd generation link speed but I cannot find it.  Can you please investigate where this is enabled? 

It is called  "Set Link Speed to G3".  I would appreciate if you would direct me to that setting.

Thank you.

 

It is called  "Set Link Speed to G3".  I would appreciate if you would direct me to that setting.

It is an auto-negotiated speed. If the drives are capable of a faster link speed than they are negotiating then it is a firmware communication issue. If you are using non-Dell drives you should expect this type of odd behavior. Our controllers are not designed to work with non-Dell drives.

You can try reflashing the firmware on the slower card. The speed negotiation is a firmware communication issue.

If these are Dell drives then I would suggest contacting support. The controller will likely need to be replaced.

Thanks