Re: Miserable Disks

this is from memory because I'm not a SAN admin anymore, but the first 4 drives of enclosure 0 grab space for the OS (CX600 - Win NT, CX700 - Win 2000 or XP ) for each SP and space to destage memory if there's a hardware (i.e. bad disk) or power failure.
It works. Our ups failed twice and it destaged the memory and powered down just fine.

steve

On Jun 4, 2006, at 12:17 AM, Henry Poras wrote:

I asked our SA about this and he said that the write cache is non volatile as long as it is enabled and the backup battery system has power. This means that the write cache should be small enough to allow it to flush its contents before the battery depowers, but given this, there is nothing to worry about.

As I am still learning EMC stuff, is this true? Are there other things that can go wrong with write cache?

Thanks.

Henry



Jared Still wrote:

Comments inline.

On 5/25/06, *Mark Brinsmead* <pythianbrinsmead@xxxxxxxxx <mailto:pythianbrinsmead@xxxxxxxxx>> wrote:

    (*) Get the biggest cache you can afford.  (Make sure it's
    *really* non-volatile.  Wolfgang
    never mentioned what happens to your database when you lose the
    contents of the write
    cache, but *I* got a taste!  And it wasn't pleasant!)


Yes, I had experience with that 2 weeks ago on a CX700.
Definitely unpleasant.

EMC claimed that we should have disable the write cache
prior to powering down the SAN.

I have since learned that the support tech in question was blowing smoke.


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Jared Still
Certifiable Oracle DBA and Part Time Perl Evangelist


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