mdraid RAID1 write performance issues

[CHONG Yu Meng]

> From: "Lonni J Friedman" <netllama at gmail.com>
> 
> Another oddity to add to the situation is that occasionally and
> unpredictably the performance will spike up to 'normal' levels. For
> example, I can copy large (5 - 40GB) files to the array and it will
> hover around 8 or 10MB/s for a while, then spike to 40 or 50MB/s for a
> few seconds, then fall back to 8MB/s for a minute or more.

Are you using Intel Storage Matrix Chipset? (I can't remember the exact 
name for it, but it is Intel and it is commonly found in Dell systems)

I've found this same behaviour when the Intel SATA/RAID controller 
starts to fail - the normal spikes, followed by the slow performance.

pascal chong