Why P840 or H240 not support 4Kn HDD in Raid mode ,but work for HBA mode

[mysy]

I try set a file server with 4 x 6TB SAS 4Kn HDD, it was seagate v5 SAS 12gb interface.

I try use P840 and ML110 Gen9 to get OS and test the HDD,  in HPE SSA, the card fine those 4Kn SAS HDD, and show them as 4Kn group other that SAS HDD.

I run the diag from SSA, it show some sense feature is 4k raid not support. 

I try H240 card too,  when it was HBA mode, HDD could see in the Win 2016 server OS or Esxi 6.7 .

But when I switch H240 to smart array mode , it also show the driver not supprt in raid mode, couldn't set those 4Kn HDD to any Raid 0 or Raid 1 volume.

Any one know why the Raid card couldn't support 4K HDD for Raid mode , but support it in HBA mode?

[sudhirsingh]

Hi,

Not sure, but seems like controller limitation.

4K native block size is not supported by the controller in RAID mode however in HBA mode drive is directly exposed to OS so it depends on OS whether it support 4Kn blocks or not.

But please do check with latest SSA version and Controller firmware, 

Download offline SSA from below link:

https://support.hpe.com/hpsc/swd/public/detail?swItemId=MTX_321a88714bff4279abf175b9bd#tab3

also ensure that controller firmware is updated to latest.

Hope this help!

Regards,

Sudhir

[mysy]

I already update the two Card fw to least version and My HPE server use least version bios and ssa .

[Rami1979]

HPE is yet to certify 4kn hard disks for their servers & the Raid cards & hence it's saying unsupported. 4kn drives are still getting tested for compatibility & commercial acceptance is yet to come through.

[Eric Zimmerman]

The reason they work for HBA mode, is because the software operating system doesn't care about the 4Kn. Recent Windows server, and Linux environments have been updated to include support, or it is now native. It is interesting to note that as far back as 2005, HP was promoting the advantages of Advanced 4Kn format drives and development in a white paper. However, 15 years later, and about that many years of increasingly marketed 4Kn manufactrue, there has never been support for them in the RAID controllers used in their Proliant (and AFAIK other) server offerings. I'm running Gen 10 equipment, and we still have yet to understand why. In short, HP, HPE and other server manufacturers seem to continue to favor the older/current 512k/512e formats. Understandably some improvements don't seem to offer quite the promised panacea that they touted. For all the storage woes that were predicted in the passed in hard drive/sector development of 4K, they now seem to be more of a past prediction of some time further (than the last 15 years) in the future. A couple of HDD manufacturers started promising/offering 512e/4Kn drives that can be switched-to-suit the controller hardware. That would have been nice previously, before people found out the hard way (by purchase). It can be argued that, those that purchased should have checked with HP first. Justifiably, some can say that it was never stated that they wouldn't support it, or point to the fact that they supported the development in other literature. But, that's just buyer's remorse. We purchased and tested four 4Kn drives some time ago, and used another manufacturer's RAID controller to evaluate the advantages as applied to the various programs and database types that our clients use. For our clients requirements and needs, there were no cleaer advantages overall. About that time, Flash storage had come-to-age and was more affordable for those that needed noticeably higher performance in their environments. Still, we have seen some opportunities to procure 4Kn drives at lower prices, than their 512K counterparts, so it can look tempting if you have the hardware that could support it.