From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: Raid 1 (non) performance Date: Mon, 20 Nov 2006 14:29:04 -0500 Message-ID: <45620200.4010206@tmr.com> References: <455B4609.6090905@kite.se> <4561B7C3.7030000@kite.se> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <4561B7C3.7030000@kite.se> Sender: linux-raid-owner@vger.kernel.org To: "Magnus Naeslund(k)" Cc: dean gaudet , linux-raid@vger.kernel.org List-Id: linux-raid.ids Magnus Naeslund(k) wrote: > dean gaudet wrote: > >> i see you have split /var and / on the same spindle... if your /home is on >> / then you're causing extra seek action by having two active filesystems >> on the same spindles. another option to consider is to make / small and >> mostly read-only and move /home to /var/home (and use a symlink or mount >> --bind to place it at /home). >> >> > > Yes I have it like this now: > /var/bind/home on /home type bind (rw,bind,noatime) > > >> hopefully your swap isn't being used much anyhow. >> >> > > Zero used, infact. > > >> try "iostat -kx /dev/sd* 5" and see if the split is causing you troubles >> -- i/o activity on more than one partition at once. >> >> > > It seems to be roughly the same numbers on the disks. > > >> turning off write caching is a recipe for disasterous performance on most >> ata disks... unfortunately. better to buy a UPS and set up nut or apcupsd >> or something to handle shutdown. or just take your chances. >> >> > > This is a mail server, I would like it to not lose mail if there is an power outage. > Is there anything one can do without buying more hardware? Nothing you can do will prevent loss of mail locally if the power goes out when the mail has gotten to memory and not disk, or the metadata has not been updated on the disk. Unless you want to hack your SMTP interface to not return an "accepted" status until you have flushed everything, get a UPS. Hint, I looked at this for an ISP internal mailer, and performance trying to flush is so bad it's only justified for a very low volume of mail. As in legal or financial stuff. If your mail is that critical you buy expensive hardware when justified. Otherwise spend a few hundred bucks on a good UPS and install the software. -- bill davidsen CTO TMR Associates, Inc Doing interesting things with small computers since 1979