adding BBU relearn support to mfiutil

Wed Nov 6 17:01:58 UTC 2013

Hi, we've been playing with this patch in the context of 8.4-RELEASE-p4 
(we extracted r250483 and r250497 from stable/8 and applied to 
releng/8.4).  I'm seeing some results that make me question whether or 
not caching is really working correctly after a BBU relearn operation 
has completed -- or maybe whether or not the new BBU patch is talking to 
LSI controller properly.

Our test system had a BBU in the failed state (relearn needed).  We used 
the "start learn command" and it seemed to go well, but strangely, when 
process is seems to have completed, and now several days later, status 
is still LEARN_CYCLE_REQUESTED (as seen with "mfiutil show battery").  
This may be entirely normal -- maybe it says that because the autolearn 
feature is now enabled?

The "cache" status command also suggests also is a bit strange. Here is 
the raw output of these status commands:

# mfiutil cache mfid0
mfi0 volume mfid0 cache settings:
              I/O caching: disabled
            write caching: write-back
write cache with bad BBU: disabled
               read ahead: adaptive
        drive write cache: enabled
Cache disabled due to dead battery or ongoing battery relearn

# ./mfiutil show battery
mfi0: Battery State:
      Manufacture Date: 3/18/2010
         Serial Number: 77
          Manufacturer: LS1111001A
                 Model: 3598501
             Chemistry: LION
       Design Capacity: 1215 mAh
  Full Charge Capacity: 65262 mAh
      Current Capacity: 61543 mAh
         Charge Cycles: 120
        Current Charge: 94%
        Design Voltage: 3700 mV
       Current Voltage: 4081 mV
           Temperature: 23 C
      Autolearn period: 30 days
       Next learn time: Tue Nov 26 20:06:40 2013
  Learn delay interval: 0 hours
        Autolearn mode: enabled
                Status: LEARN_CYCLE_REQUESTED

/Why does cache status now say  "Cache disabled due to dead battery or 
ongoing battery relearn"/?  Shouldn't this no longer be the case since 
I've run the "learn" operation?  Does this indicate that the I/O caching 
is really disabled?

I'd appreciate any and all assistance.  Here's a bit of other info that 
might be of interest:

# mfiutil show adapter
mfi0 Adapter:
     Product Name: Integrated Intel(R) RAID Controller SROMBSASMP2
    Serial Number:
         Firmware: 11.0.1-0036
      RAID Levels: JBOD, RAID0, RAID1, RAID5, RAID6, RAID10, RAID50
   Battery Backup: present
            NVRAM: 32K
   Onboard Memory: 512M
   Minimum Stripe: 8k
   Maximum Stripe: 1M

# mfiutil show drives
mfi0 Physical Drives:
  1 (  136G) ONLINE    <SEAGATE ST9146852SS 0005 serial=6TB005JE> SAS E1:S0
  2 (  136G) ONLINE    <SEAGATE ST9146852SS 0005 serial=6TB005JV> SAS E1:S1
  3 (  136G) ONLINE    <SEAGATE ST9146852SS 0005 serial=6TB005KD> SAS E1:S4
  4 (  136G) ONLINE    <SEAGATE ST9146852SS 0005 serial=6TB005BQ> SAS E1:S2
  5 (  136G) HOT SPARE <SEAGATE ST9146852SS 0005 serial=6TB005FJ> SAS E1:S3

The storage volume is 4-drives, RAID10.  System has 16GB RAM, dual Xeon 
E5530 CPUs, on an Intel S5520UR motherboard.

Thanks!

Charles Owens
Great Bay Software

On Fri Apr 5 20:08:09 2013, Mark Johnston wrote:
>
> On Fri, Apr 05, 2013 at 02:22:36PM -0700, Sean Bruno wrote:
>>
>> On Sun, 2013-03-03 at 22:38 -0500, Mark Johnston wrote:
>>>
>>> Hi Everyone,
>>>
>>> I recently needed to add a couple of features to mfiutil related to BBU
>>> relearning. I've pasted a patch below which
>>>
>>> 1. adds extra fields to the output of "mfiutil show battery" showing BBU
>>> properties. This is essentially the output of
>>>
>>> # MegaCli -AdpBbuInfo -GetBbuProperties -aLL
>>>
>>> and consists of info about battery learning: the learn period, the
>>> time at which the controller will start the next relearn, and the BBU
>>> mode (which indicates whether the battery supports transparent
>>> relearning).
>>>
>>> 2. adds a couple of subcommands under "mfiutil bbu" which lets users set
>>> the BBU properties which can be set by MegaCli.
>>>
>>> 3. adds a command "mfiutil start learn" which immediately kicks off a
>>> battery relearn.
>>>
>>> These changes grew out of concern about the fact that the controller
>>> write cache is set to write-through mode during a relearn period (which
>>> usually lasts for several hours). This ended up causing some mysterious
>>> and intermittent performance issues, so I needed a way of getting more
>>> info about what was going on (using MegaCli isn't really an option for
>>> several reasons). Some BBUs support transparent relearning, which
>>> basically means that the controller write cache doesn't get turned off
>>> during a relearn. However, LSI's default config doesn't enable it, and
>>> now mfiutil can be used to do that (through "mfiutil bbu bbu-mode").
>>>
>>> I was hoping someone would be able to review the patch. If anyone's able
>>> and willing to test it, I'd very much appreciate feedback from that.
>>>
>>> Thanks!
>>> -Mark
>>
>>
>> Just to document for the record. Finally got around to testing this
>> today with Mark providing updates. Looks good overall with a couple of
>> nits that he is handling at the moment (man page and variable name
>> collision).
>
>
> The updated patch is here:
> http://people.freebsd.org/~markj/patches/20130405-mfi-bbu.diff
>
> I'll commit it in a few days if there aren't any problems.
>
> Thanks,
> -Mark
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