From mboxrd@z Thu Jan 1 00:00:00 1970 From: Bill Davidsen Subject: Re: In this partition scheme, grub does not find md information? Date: Sat, 02 Feb 2008 15:17:19 -0500 Message-ID: <47A4CFCF.4000203@tmr.com> References: <479EAF42.6010604@pobox.com> <18334.46306.611615.493031@notabene.brown> <479F07E1.7060408@pobox.com> <479F0AAB.3090702@rabbit.us> <479F331F.7080902@msgid.tls.msk.ru> <479F3C74.1050605@rabbit.us> <479F42A5.8040007@msgid.tls.msk.ru> <479F5177.6060206@pobox.com> <479F557D.20502@rabbit.us> <479F7FCD.7030106@pobox.com> <47A07796.2010805@msgid.tls.msk.ru> <47A0855A.1010901@pobox.com> <47A1E259.8000000@tmr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <47A1E259.8000000@tmr.com> Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org Cc: Moshe Yudkowsky , Michael Tokarev List-Id: linux-raid.ids Bill Davidsen wrote: > Moshe Yudkowsky wrote: >> Michael Tokarev wrote: >> > >> To return to that peformance question, since I have to create at >> least 2 md drives using different partitions, I wonder if it's >> smarter to create multiple md drives for better performance. >> >> /dev/sd[abcd]1 -- RAID1, the /boot, /dev, /bin/, /sbin >> >> /dev/sd[abcd]2 -- RAID5, most of the rest of the file system >> >> /dev/sd[abcd]3 -- RAID10 o2, a drive that does a lot of downloading >> (writes) >> > I think the speed of downloads is so far below the capacity of an > array that you won't notice, and hopefully you will use things you > download more than once, so you still get more reads than writes. > >>> For typical filesystem usage, raid5 works good for both reads >>> and (cached, delayed) writes. It's workloads like databases >>> where raid5 performs badly. >> >> Ah, very interesting. Is this true even for (dare I say it?) >> bittorrent downloads? >> > What do you have for bandwidth? Probably not more than a T3 (145Mbit) > which will max out at ~15MB/s, far below the write performance of a > single drive, much less an array (even raid5). It has been pointed out that I have a double typo there, I meant OC3 not T3, and 155Mbit. Still, the most someone is likely to have, even in a large company. Still not a large chance of being faster than the disk in raid-10 mode. -- Bill Davidsen "Woe unto the statesman who makes war without a reason that will still be valid when the war is over..." Otto von Bismark