amediratta

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amediratta

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2014 Posts

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May 3rd, 2009 08:00

Cache Area

We say we have battery protected cache so whatever is in cache is battery protected. What would happen if the battery has lived it's life and the system is still not ON? Do we loose data in cache OR is there any other mechanism that helps protect it?
  • RyanP2

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    Posted May 4th, 2009 08:00

    Cache is immediately destaged to the vault upon a power loss. The Clariion will then begin an orderly shutdown. The batteries are only there to protect cache and dump it when there is power loss, not keep the array up an running for as long as it can hoping power comes back on.
  • Loudenj

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    Posted May 3rd, 2009 14:00

    Hi Anuj,

    During a situation where you have lost power to your SAN, the cache is written to the first set of disk's (the vault). When the power is returned the cache written to the disk is read, and committed to the correct lun.

    Cheers
    John

    Message was edited by: John to correct atypo or two
    Loudenj
  • amediratta

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    Posted May 4th, 2009 08:00

    Does it mean that the time there is a power loss, cache would immediately get destaged to the vault area? OR the cache and the vault area have same length battery backup and it would get destaged when the baterry backup is also over?
  • amediratta

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    Posted May 4th, 2009 08:00

    Thanks Ryan
  • bigjoe1

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    Posted May 4th, 2009 11:00

    If your batteries are faulted then write cashe will be disabled and all write data will go directly to disk, by passing cache.
  • modaslam

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    Posted May 12th, 2009 10:00

    how to check that write cache is disabled or not.
  • kelleg

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    Posted May 12th, 2009 11:00

    In Navisphere, right click on the array icon and select Properties then click on the cache tab - there are three check boxes - two for Read cache and one for Write cache. This is the system cache. Each LUN can also have its read or write cache set individually - again, right click on a LUN and select properties and select the cache tab.

    glen
  • modaslam

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    Posted May 26th, 2009 07:00

    Thanks
    Glen