Re: Reliability recommendations

Mark,

On 2/24/06 10:10 PM, "Mark Kirkwood" <markir(at)paradise(dot)net(dot)nz> wrote:

> Well, since this is always fun (2G memory, 3Ware 7506, 4xPATA), writing:
>
> $ dd if=/dev/zero of=/data0/dump/bigfile bs=8k count=500000
> 500000 records in
> 500000 records out
> 4096000000 bytes transferred in 32.619208 secs (125570185 bytes/sec)

> Reading:
>
> $ dd of=/dev/null if=/data0/dump/bigfile bs=8k count=500000
> 500000 records in
> 500000 records out
> 4096000000 bytes transferred in 24.067298 secs (170189442 bytes/sec)

Not bad at all! I have one of these cards in my home machine running WinXP
and it's not nearly this fast.

> Hmmm - a bit humbled by Luke's machinery :-), however, mine is probably
> competitive on (MB/s)/$....

Not sure - the machines I cite are about $10K each. The machine you tested
was probably about $1500 a few years ago (my guess), and with a 5:1 ratio in
speed versus about a 6:1 ratio in price, we're not too far off in MB/s/$
after all :-)

> It would be interesting to see what Dan's system would do on a purely
> sequential workload - as 40-50MB of purely random IO is high.

Yeah - that is really high if the I/O is really random. I'd normally expect
maybe 500-600 iops / second and if each IO is 8KB, that would be 4MB/s. The
I/O is probably not really completely random, or it's random over cachable
bits of the occupied disk area.

- Luke