From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roberto Spadim Subject: Re: What's the typical RAID10 setup? Date: Thu, 3 Feb 2011 14:07:10 -0200 Message-ID: References: <20110203154305.GA27356@www2.open-std.org> <20110203160245.GD27356@www2.open-std.org> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20110203160245.GD27356@www2.open-std.org> Sender: linux-raid-owner@vger.kernel.org To: =?ISO-8859-1?Q?Keld_J=F8rn_Simonsen?= Cc: Drew , Linux-RAID List-Id: linux-raid.ids 2011/2/3 Keld J=F8rn Simonsen : > On Thu, Feb 03, 2011 at 01:50:49PM -0200, Roberto Spadim wrote: >> hummm, nice >> keld (or anyone), do you know someone (with time, not much, total ti= me >> i think it?s just 2 hours) to try develop modifications on raid1 >> read_balance function? > > maybe our very productive Polish friends at Intel could have a look. > But then again, I am not sure it is productive. I think raid1 is OK, > You could have a look at raid10, where "offset" has been discussed as > being the better layout for ssd. ok, i think that there=B4s no 'better' layout for ssd since ssd don=B4= t have a variable access time like head on hard disk it=B4s better because today read balance is optimized for minimal distance (nearest head) but it=B4s not true that layout for ssd is better >> what modification, today read_balance have distance (current_head - >> next_head), multiply it by a number at /sys/block/md0/distance_rate, >> and make add read_size*byte_rate (byte_rate at >> /sys/block/md0/byte_read_rate), with this, the algorithm will make >> minimal time, and not minimal distance >> with this, i can get better read_balance (for ssd) >> for a second time we could implement device queue time to end (i thi= nk >> we will work about 1 day to get it working with all device >> schedulers), but it?s not for now > > Hmm, I thought you wanted to write new elevator schedulers? no, it=B4s not a elevator, it=B4s a raid1 read balance, based on time (each sda,sdb,sdc,sdd can have you elevator without problem) it=B4s lik= e a elevator for raid1 (mirror), some other raid could use it too (raid10, i don=B4t know if raid5 have mirror, but if yes, could use too= ) > > best regards > keld thanks, keld --=20 Roberto Spadim Spadim Technology / SPAEmpresarial -- To unsubscribe from this list: send the line "unsubscribe linux-raid" i= n the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html