[CentOS] Re: raid5 crash

[Bryan J. Smith]

On Sat, 2005-07-09 at 15:46 -0500, Bryan J. Smith wrote:
> Yes, 3Ware cards (prior to the 9000 series) "suck" at RAID-5 writes, 
> because the use a small amount of costly (transistor-wise) SRAM.  But
> using SRAM also means it doesn't need battery backup either.

Let me rephrase that ...

As long as power is delivered to the card, or has been delivered within
the last few seconds, the data in the SRAM remains, and can be flushed.
This is different than DRAM where you need both A) a logic that
refreshes the data B) power to do A

The power usage of SRAM versus DRAM is orders of magnitude.

Now on the Escalade 9000 series, you do need battery backup to guarantee
the DRAM is maintained between freezes and lock-ups.


-- 
Bryan J. Smith                                     b.j.smith at ieee.org 
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