ZFS raid write performance?

[Quartz]

>> What's sequential write performance like these days for ZFS
>> raidzX? Someone suggested to me that I set up a single not-raid
>> disk to act as a fast 'landing pad' for receiving files, then move
>> them to the pool later in the background. Is that actually
>> necessary? (Assume generic sata drives, 250mb-4gb sized files, and
>> transfers are across a LAN using single unbonded GigE).
>
> That sounds really weird recommendation IMHO.  Did "someone" explained
> with the reasoning/benefit of that "landing pad"?

Sort of. Something about the checksum calculations causing too much 
overhead. I think they were confused about sequential write vs random 
write, and possibly mdadm vs zfs. It was just something mentioned in 
passing that I didn't want to start a debate about at the time, since I 
wasn't 100% sure.


>a single hard drive won't do much beyond 100MB/s (maybe
> 120MB/s max) for sequential 128kB blocks, so that "landing pad" would
> probably not very helpful assuming you can saturate your GigE network

Wait, I'm confused. A single GigE has a theoretical max of like 
100mb/sec. That would imply the drive is probably about the same speed?