Re: [Aoetools-discuss] Page-caching

[Tracy R R. <tr...@ul...>]

Anthony Wright wrote:
> I hate to say it, but page caching isn't actually desirable for vblade
> because it means that if the machine vblade is running on crashes the
> data you thought you're filesystem or raid array thought it had written
> to disk was actually still in memory on the vblade machine. This can
> lead to corrupted raid arrays - look up all the bad experiences of write
> caching on raid arrays.

I beg to differ. I have used various big disk array products from 
StorageTek, EMC, MTI, and others and they all did caching in the disk 
array controller itself (analogous to the AoE server in our case) and 
they had battery backups to guarantee that data would get written to 
disk. On the first sign of power failure these machines would flush 
their cache and power themselves off. My AoE servers have 512M of RAM 
each and I'm sure that 512M of RAM really helps with IO performance on 
the cpu nodes.

-- 
Tracy R Reed                  http://ultraviolet.org
A: Because we read from top to bottom, left to right
Q: Why should I start my reply below the quoted text