Re: File system compression, not at the block layer

[Timothy Miller]

Ben Greear wrote:
> Richard B. Johnson wrote:
>
> > Actually not. You need a FIFO to cache your bits into buffers of bytes
> > anyway. Depending upon the length of the FIFO, you can "rubber-band" a
> > lot of rotational latency. When you are dealing with a lot of drives,
> > you are never going to have all the write currents turn on at the same
> > time anyway because they are (very) soft-sectored, i.e., block
> > replacement, etc.
>
>
> Wouldn't this pretty much guarantee worst-case latency scenario for 
> reading, since
> on average at least one of your 32 disks is going to require a full 
> rotation
> (and probably a seek) to find it's bit?


Only for the first bit of a block.  For large streams of reads, the 
fifos will keep things going, except for occasionally as drives drift in 
their relative rotation positions which can cause some delays.


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