Read/Write speed issues with PERC 5/i running 10 - 1TB WD1002FBYS

I have 3 identical Dell Power Edge servers with with all the same specs. Each units uses a PERC 5/i controller to run 10 - 1TB WD1002FBYS drives. All drives are in RAID 5 and initialized. My DRAC 5 cards shows that all raid batteries are good. On the first 2 servers the read write is great and the third has terrible write speed. see pictures. The PERC 5/i was set to write through when i setup the VD, but it is now write through instead. From what i read this can be caused be bad battery for raid or hard drives. The drives in this units are partial HP drives with the firmware of HPG0. Can this be the issue? I was told these drives were the same just the TLER difference. I can't dismantel the good servers since the data is too important to loose. There are posts on here about the WD1002FBYS and firmware upgrading, but i cant tell if anyone every actaully got the firmware. I am willing to try firmware change in one of the drives is someone has it.

i have broken the VD, removed the HP drives from the raid and started to setup a new raid 5. Initalization is running now. If this works then i will try the HP drives by themseves.

FYI. 30 TB of storage total..

have you checked the firmware on the raid controllers?

Firmware is up to date on all 3 servers on everything including the perc 5/i. I am baffled.

just ran crystal disk mark 2.2 on the 4 raid 5 drives and got a write speed above 121. i will now install 4 of the hp drives and see if i have the same issue...

After hours of initialization i have found that the only way the PERC 5/i will go to write back is to force with no BBU unit. I am now confused becasue the DRAC shows batteries are good for the storage controller, unless it is wrong? I am going to purchase a new battery dell OEM from Ebay and test again.

I think i have this figured out. The drac pretty much considers all batteries good if they have some voltage retention regardless if they are strong enough to operate. The Perc 5/i card performs an endurance test on the battery and will switch to write through apon the batteries not being strong enough. There is no feedback from the perc card that the batteries need to be changed!!! I purchase a new battery, first 30 minutes the perc tested, and then the write speeds are about 600 MB/sec now...What a pain in the ass...but worth it to have my now 36TB system running...

Very cool. Thats interesting that DRAC sort of falls short. Thanks for the update.