From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sebastian Kuzminsky Subject: Raid sync observations Date: Tue, 20 Dec 2005 10:18:26 -0700 Message-ID: Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids I just created a RAID array (4-disk RAID-6). When "mdadm -C" returned, /proc/mdstat showed it syncing the new array at about 17 MB/s. "vmstat 1" showed hardly any blocks in or out, and an almost completely idle cpu. Question 1: Why didnt the raid sync I/O show up with vmstat? Question 2: Why was it limited to 17 MB per second? The maximum was left at the default, 200 MB/s. The min was also at the default, 1 MB/s. I get 60 MB/s per disk with "hdparm -tT" (that's using one disk at a time, but still). The checksumming code does > 3 GB/s. Just curious really. This is with 2.6.15-rc5 and SATA disks via libata. -- Sebastian Kuzminsky