From mboxrd@z Thu Jan 1 00:00:00 1970 From: Paul Clements Subject: Re: Software RAID level 1 issue Date: Fri, 30 May 2003 16:31:19 -0400 Sender: linux-raid-owner@vger.kernel.org Message-ID: <3ED7BF97.BAB11B12@SteelEye.com> References: <1054403067.14818.280.camel@testlin.hades> <3ED7B898.4409555F@SteelEye.com> <01f101c326e7$c9084890$7b07a8c0@pluto> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: To: 3tcdgwg3 <3tcdgwg3@prodigy.net> Cc: Stef Telford , 'Greg Rasberry' , 'Linux raid mailing list' List-Id: linux-raid.ids 3tcdgwg3 wrote: > If there is a plan to do a "intelligent resync", like some of the raid > controller > vendors offer? The resync process will be hold on, if there are IO requests > from upper level, and resumed when there is no IO. By doing that, the > system > performance always be on the top. I am very interested in having something > like that. This wasn't exactly what I meant by intelligent resync, but...I think what you're asking about is something that the md driver already does to some extent. It will slow down a resync if there is active I/O on the device. This can even be tuned by the user by manipulating a couple of kernel sysctls: apache:~# cat /proc/sys/dev/raid/speed_limit_min 100 apache:~# cat /proc/sys/dev/raid/speed_limit_max 10000 apache:~# echo 1000000 > /proc/sys/dev/raid/speed_limit_max apache:~# cat /proc/sys/dev/raid/speed_limit_max 1000000 These are in KB/s. The "min" refers to the maximum I/O bandwidth that will be consumed by resyncs before the resyncs get throttled, when there is other I/O activity on the device. The "max" refers to the maximum I/O bandwidth that will be consumed by resyncs before the resyncs get throttled, even if there is no other I/O activity on the device. -- Paul