Joerg Schilling wrote:
> Andrew Gabriel <[EMAIL PROTECTED]> wrote:
>> Andrew Gabriel wrote:
>>> Interesting idea, but for 7200 RPM disks (and a 1Gb ethernet link), I
>>> need a 250GB buffer (enough to buffer 4-5 seconds worth of data). That's
>>> many orders of magnitude bigger than SO_RCVBUF can go.
>> No -- that's wrong -- should read 250MB buffer!
>> Still some orders of magnitude bigger than SO_RCVBUF can go.
>
> It's affordable e.g. on a X4540 with 64 GB of RAM.
I guess the architectures with limited 256MB and 512MB kernel address
space are mostly retired now.
> ZFS started with constraints that could not be made true in 2001.
>
> On my first Sun at home (a Sun 2/50 with 1 MB of RAM) in 1986, I could
> set the socket buffer size to 63 kB. 63kB : 1 MB is the same ratio
> as 256 MB : 4 GB.
>
> BTW: a lot of numbers in Solaris did not grow since a long time and
> thus create problems now. Just think about the maxphys values....
> 63 kB on x86 does not even allow to write a single BluRay disk sector
> with a single transfer.
I have put together a simple set of figures I use to compare how disks
and systems have changed over the 25 year life of ufs/ffs, which I
sometimes use when I give ZFS presentations...
25 years ago Now factor
------------ --- ------
Disk RPM 3,600 10,000 x3
Disk IOPS 30 300 x10
Disk Data rate 0.96MB/s 75MB/s x80
Capacity 100MB 1TB x10,000
System MIPS 4 400,000 x100,000
--
Andrew
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