illumos gate

Some of the LSI chips which are supported by the mr_sas driver can be configured in HBA mode.
When in this mode, the mr_sas driver does not pass mode sense commands through to the hardware. This results in error messages during boot and ZFS being unable to set write caching on drives.

In testing with the Dell HPERC H730p adapter, based on the LSI MegaRAID SAS-3 3108 (Invader) chip, boot looks like:

NOTICE: map sync received, switched map_id to 1

NOTICE: LDMAP sync completed.
WARNING: /pci@0,0/pci8086,2f02@1/pci1028,1f49@0/sd@0,1 (sd0):
        Command failed to complete...Device is gone

WARNING: /pci@0,0/pci8086,2f02@1/pci1028,1f49@0/sd@1,1 (sd1):
        Command failed to complete...Device is gone

Hostname: carolina
WARNING: /pci@0,0/pci8086,2f02@1/pci1028,1f49@0/sd@4,1 (sd6):
        Command failed to complete...Device is gone
... etc.

It is also not possible to view or modify write caching through format -e

carolina# (6) format -e
selecting c0t2d1
format> cache
cache> write
write_cache> disp
Mode sense failed.
write_cache> enable
Mode sense failed.

Nor can any mode sense pages be retrieved using a tool such as <i>sdparm</i>:

carolina# (10) sdparm -a /dev/rdsk/c0t2d1s0
    /dev/rdsk/c0t2d1s0: SEAGATE   ST91000640SS      0004
mode sense (10): pass through os error: I/O error
mode sense (10): pass through os error: I/O error
mode sense (10): pass through os error: I/O error
mode sense (10): pass through os error: I/O error
mode sense (10): pass through os error: I/O error
mode sense (10): pass through os error: I/O error
mode sense (10): pass through os error: I/O error
... etc.

I have an initial patch for this which I'll be sending to the developers' list for review this week.

With the patch:

... Clean boot ...

format -e
...
write_cache> displ
Write Cache is enabled

carolina# (4) sdparm -a /dev/rdsk/c0t2d1s2
    /dev/rdsk/c0t2d1s2: SEAGATE   ST91000640SS      0004
Read write error recovery mode page:
  AWRE        1  [cha: y, def:  1, sav:  1]
  ARRE        1  [cha: y, def:  1, sav:  1]
  TB          0  [cha: y, def:  0, sav:  0]
  RC          0  [cha: y, def:  0, sav:  0]
  EER         0  [cha: y, def:  0, sav:  0]
  PER         0  [cha: y, def:  0, sav:  0]
... many more lines deleted