From mboxrd@z Thu Jan 1 00:00:00 1970 From: "George Spelvin" Subject: RAID6 syncing at 24 MB/s? Date: 18 Apr 2012 00:35:40 -0400 Message-ID: <20120418043540.19923.qmail@science.horizon.com> Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: linux@horizon.com List-Id: linux-raid.ids I'm putting together a 7x2TB RAID6 for a home media server, and after encountering a fun kernel bug building the array (old kernel, a new one fixed it), I fot things working, but now notice that each disk is syncing at 23.8 MB/s. hdparm -t reports they can do well over 100 MB/s each, and the processor, while only an i3, is spending about 20% of one core in the raid6 task. Basicall, it was created with: mdadm -C -l 6 -n 7 -c 128 -b internal /dev/md0 /dev/sd[b-h] (The kernel bug was in 2.6.35, and was triggered by forgetting the "/dev/md0"; one of the RAID ioctls it tries confused up the /dev/sd driver quite thoroughly) It's an Intel chipset motherboard with a jmicros 2xSATA+PATA chip, and one port on a SiI3132 plug-in card. And mostly cheap Caviar green EARS drives (yes, I know about the lack of TLER). Note that I didn't partition the drives, so there's no risk of a 4K-unaligned partition. A friend with his own Linux media server said he saw the exact same speed building his RAID6 array. The speed_limit_max is set to the default, the system is idle, and the resultant md drive is not mounted. Is there a web page somewhere with speed tuning suggestions? Thank you!