Bug : S100i SR doesn't reactivate Physical Drive Write Cache after init - state shows ena

[BritannyTech]

Hello,

I noticed a bug in Physical Drive Write cache enablement of S100i SR controller not enabling the cache after a reboot or power up, with RAID volumes managed (RAID 1/5), in each and every server configuration I could encounter.

Bug scope :
- Windows 2016 / 2019 and 2022 x86-64 are all equally impacted
- All drivers release since 2 years. Current 106.12.6.0 release included.
- All SSA GUI since release 5.30.x and higher
- All type of server with S100i SR controller enabled : ML30 Gen10, ML110 Gen10, Microserver Gen10+
- For every volume managed by the S100i SR, even if the boot OS volume is on a separate NVMe SSD not managed by the S100i SR (as a NVMe SSD on the mainboard M.2 slot if applicable, or a PCIe M.2 NVMe card)

I confirmed the issue on two of each type of ML30/110 Gen10 server and Microserver Gen10+. OS are a mix of Windows Server 2016 Standard, 2019 Standard and 2022 Standard x64. Each has the issue.

The bug is : at boot or reboot, the Smart Storage Administrator utility shows a Physical Drive Write Cache in *Enabled* state.

Performance tests clearly show the cache is not effectively enabled : poor disk performance in multiple I/O, or by simply defragmenting the volume. The impact of 128 MB or 256 MB (usual capacity on 4TB + hard disks) disabled disk cache on the disks is quite huge.

Yes, physical cache loss can be an issue in case of grid power loss with no UPS.
(Physical disk cache must be distinguished from raid controller cache, usually backed up by a battery or flash module. Backed Raid controllers usually disable physical disk cache to avoid cache flush in case of power loss and maintain integrity of data)

Manual fix applicable : by toggling to Disabled then Enabled again the cache state in SSA GUI, the cache immediately works and performance perks up (by a x3 to x10 ratio increase).

Automatic fix applicable to automatically enable the Physical Drive Write cache at Windows startup :

- Install HP SSA CLI 5.30 or more (Command Line Interface of SSA)
- Run a .cmd task at system startup with admin rights (might need to add the account the rights to start as a task with a GPO) :

ping 127.0.0.1 -n 30
cd \
cd "C:\Program Files\Smart Storage Administrator\ssacli\bin\"
ssacli ctrl slot=0b modify dwc=disable
ssacli ctrl slot=0b modify dwc=enable forced
exit

Tests shows the S100i seems to always use slot=0b for its ID, so the fix script should be universal.

[Sunitha_Mod]

Hello @BritannyTech, 

Thank you for sharing the information. I hope this will help the community users. 

[BritannyTech]

Thanks. Fixing the driver's init state issue would be even better.

[tyec]

It's same for me ... really amazing.

Affected server : Microserver gen10 plus

[AlexanderB1]

This is clearly huge bug - how to enable the disks write cache in ESXi? Without enabling the write cache the performance is horrible.

[BPSingh]

Greetings!

Please refer 7.3.38 Enabling or Disabling the Drive Cache on page# 34 of the HPE Smart Storage Administrator CLI User Guide

https://support.hpe.com/hpesc/public/docDisplay?docLocale=en_US&docId=dp00002635en_us