RAID Followup

Following up on yesterday’s post about my slow server, I just discovered why the RAID reconstruction was going so slowly. When the disc in question was knocked offline, all of the hdparm settings (most notably DMA) were reset. A simple:

 hdparm -c 1 -d 1 -u 1 /dev/hde 

Instantly quadrupled the speed of RAID reconstruction, and also sped up the whole server noticeably.

So, tip for the future (and for Google searchers): if your RAID is reconstructing very slowly, be sure to check the hdparm settings for all of the member discs.