From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Raid5 Read stats for parity cal... Date: Thu, 17 Sep 2009 12:38:48 +1000 Message-ID: <19121.41272.564725.505554@notabene.brown> References: Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from Linux Raid Study on Wednesday September 16 Sender: linux-raid-owner@vger.kernel.org To: Linux Raid Study Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids On Wednesday September 16, linuxraid.study@gmail.com wrote: > Hello: > > I understand that parity calculations are not done as part of Raid5 > read operation in normal running conditions. Correct. > > However, it would be done during disk failure or when a sector is bad. Also correct. > Is there a way (any stats) available to see if parity cal are done > when sector is bad (since this is not as obvious as a disk fail...) > Maybe you want /sys/block/mdX/md/dev-YYY/errors which counts the number of sectors for which md found a read error and had to generate correct data using parity, and then wrote that correct data back. NeilBrown