Hangs with mrsas?

[Garrett Wollman]

I have a new Dell server with a typical Dell hardware RAID.  pciconf
identifies it as "MegaRAID SAS-3 3008 [Fury]"; mfiutil reports:

mfi0 Adapter:
    Product Name: PERC H330 Adapter
   Serial Number: 5AT00PI
        Firmware: 25.3.0.0016
     RAID Levels:
  Battery Backup: not present
           NVRAM: 32K
  Onboard Memory: 0M
  Minimum Stripe: 64K
  Maximum Stripe: 64K

Since I'm running ZFS I have the RAID functions disabled and the
drives are presented as "system physical drives" ("mfisyspd[0-3]" when
using mfi(4)).  I wanted to use mrsas(4) instead, so that I could have
direct access to the drives' SMART functions, and this seemed to work
after I set the hw.mfi.mrsas_enable tunable, with one major exception:
all drive access would hang after about 12 hours and the machine would
require a hard reset to come back up.

Has anyone seen this before?  The driver in head doesn't appear to be
any newer.

-GAWollman