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Conference ssag::ask_ssag

Title:Ask the Storage Architecture Group
Notice:Check out our web page at http://www-starch.shr.dec.com
Moderator:SSAG::TERZAN
Created:Wed Oct 15 1986
Last Modified:Fri Jun 06 1997
Last Successful Update:Fri Jun 06 1997
Number of topics:6756
Total number of notes:25276

6496.0. "Battery Conditions and Failover in HSZ" by TROOA::HAZLETT (Bob Hazlett @KIT) Wed Mar 19 1997 12:33

    I have some questions from a customer. I'm pretty sure that 1 and 2 are
    true but I'm not sure about 3.
    
    1. If the battery is "low" and the cache policy is set as B, please
    confirm that the controller will automatically go to write through cach
    mode.
    
    2. If the battery is "bad", the manual indicates that raid sets /
    mirrored sets will be inoperative - is this true?
    
    3. Ken has a redundant controller setup. In the case of a bad or low
    battery condition on one controller, will it not failover to the second
    controller so he doesn't need to be concerned about bad or low
    batteries?
    
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6496.1CSC32::M_DIFABIOMOVL #OPINION,EXE$GL_BLAKHOLETue Mar 25 1997 14:169
    You don't mention your firmware version. Is it V27Z? If batteries are
    low and Cache Policy is B, the mirrorsets,raidsets, jbods... operate in
    write through mode. Batteries are only low upon controller power up. If
    the batteries do not charge fully within 10 hours (I think it is 10
    hours) the batteries transition to a Bad state. Depending on the
    firmware you have, that may cause Raid and Mirrorsets to become
    unavailable to the os.
    
                   Mark d.
6496.2Cache battery failuresSSDEVO::THOMPSONPaul Thompson, Colorado SpringsWed Mar 26 1997 16:5030
Another shot at the same answers.  my comments by the >>>

    1. If the battery is "low" and the cache policy is set as B, please
    confirm that the controller will automatically go to write through cach
    mode.

>>>	Low conditions can only exist in the first ten hours after the controller
>>>	is booted.  If this condition exists and cache policy B is selected, 
>>>	access to RAID and Mirror sets will be allowed through the write back
cache.
    
    2. If the battery is "bad", the manual indicates that raid sets /
    mirrored sets will be inoperative - is this true?

>>>	With UNIX and HSOF V2.7, access to RAID and mirror sets is denied.  With
>>>	VMS and 2.7, device failover to the redundnant pair of the controller 
>>>	should occur.  With UNIX and 3.0, the battery failure should cause the 
>>>	controller to shut itself down, initiating failover of the devices to the
>>>	good controller in the pair, assuming that there is one.  If no 
>>>	operational member is available to failover to, or if this is a single 
>>>	controller, access to RAID and Mirror sets will be denied and access to
>>>	JBOD will be permitted.
    
    3. Ken has a redundant controller setup. In the case of a bad or low
    battery condition on one controller, will it not failover to the second
    controller so he doesn't need to be concerned about bad or low
    batteries?

>>>	See 2 above.