From mboxrd@z Thu Jan 1 00:00:00 1970 From: Reindl Harald Subject: Re: Recovery on new 2TB disk: finish=7248.4min (raid1) Date: Thu, 27 Apr 2017 21:42:27 +0200 Message-ID: References: <590117CD.1000009@tesco.net> <22785.65375.947842.648174@quad.stoffel.home> <5492628.c8B43Z4h0G@matkor-lenovo> <22786.16524.435313.304834@quad.stoffel.home> Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <22786.16524.435313.304834@quad.stoffel.home> Content-Language: de-CH Sender: linux-raid-owner@vger.kernel.org To: John Stoffel , Mateusz Korniak Cc: Ron Leach , linux-raid@vger.kernel.org List-Id: linux-raid.ids Am 27.04.2017 um 21:03 schrieb John Stoffel: > Mateusz> They will be synced one by one, just like one big md device. > > No, big MD devices are sync'd in parallel assuming MD thinks they're > on seperate devices if they are on sepearte drives it's no problem and no "seek storm" > Now in this case I admit I might have jumped the > gun, but I'm mostly commenting on the use of multiple MD RAID setups > on a single pair of disks. > > It's inefficient. It's a pain to manage. You lose flexibility to > resize. which don't matter if you have LVM on top > Just create a single MD device across the entire disk (or possibly two > if you want to boot off one mirrored pair) and then use LVM on top to > carve out storage. More flexible but you can't boot from a RAID5/RAID6/RAID10 so you have a single point of failure of a single boot disk or need at least two additional disks for a redundant boot device frankly on a proper designed storage machine you have no need for flexibility and resize because for it's entire lifetime you have enough storage at all and in case of LVM it don't matter how many md-devices are underlying the LVM