From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roy Sigurd Karlsbakk Subject: Re: raid-5 initiated as raid-4? Date: Thu, 7 Feb 2013 18:56:12 +0100 (CET) Message-ID: <23689346.18.1360259772196.JavaMail.root@zimbra> References: <20130207175328.GA5391@cthulhu.home.robinhill.me.uk> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: QUOTED-PRINTABLE Return-path: In-Reply-To: <20130207175328.GA5391@cthulhu.home.robinhill.me.uk> Sender: linux-raid-owner@vger.kernel.org To: Robin Hill Cc: Linux RAID List-Id: linux-raid.ids > > root@raidtest:~# cat /proc/mdstat > > Personalities : [linear] [multipath] [raid0] [raid1] [raid6] [raid5= ] > > [raid4] [raid10] > > md0 : active raid5 vdf[5](S) vde[4](S) vdd[3] vdc[1] vdb[0] > > 4191232 blocks super 1.2 level 5, 512k chunk, algorithm 2 > > [3/3] [UUU] >=20 > Where did vde & vdf spring from? They weren't in your create command = - > did you add those as spares later? Yes > > > Does this mean the raid-5 is actually initiated as a raid-4? > > > RAID-5 is always created with n-1 disks, with the final disk being > recovered afterwards. It's quicker to do a linear read from the other > disks and a linear write onto the final disk (creating parity or > rebuilding the data as needed) than it is to intersperse reads & > writes > on all disks and just create the parity data (for RAID5 anyway - > reconstructing the data on a RAID6 from P & Q parity is far more > expensive, so it's quicker to just generate the parity there). ok, so do I understand correctly that the initial raid-5 build only wri= tes data/parity to a single drive (the 'replacement')? Doing some more = testing now to see what I can find=E2=80=A6 Vennlige hilsener / Best regards roy -- Roy Sigurd Karlsbakk (+47) 98013356 roy@karlsbakk.net http://blogg.karlsbakk.net/ GPG Public key: http://karlsbakk.net/roysigurdkarlsbakk.pubkey.txt -- I all pedagogikk er det essensielt at pensum presenteres intelligibelt.= Det er et element=C3=A6rt imperativ for alle pedagoger =C3=A5 unng=C3=A5= eksessiv anvendelse av idiomer med xenotyp etymologi. I de fleste tilf= eller eksisterer adekvate og relevante synonymer p=C3=A5 norsk. -- 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