From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mario 'BitKoenig' Holbe Subject: Re: Can md/mdadm deal with non-standard size of internal bitmap? Date: Fri, 18 Sep 2009 20:53:41 +0200 Message-ID: References: <1253036371.9142.1.camel@lgelinas> Return-path: Sender: linux-raid-owner@vger.kernel.org To: linux-raid@vger.kernel.org List-Id: linux-raid.ids NeilBrown wrote: > with 1.x metdata there is no "standard size" for bitmaps. Okay, I was just not sure about superblock-updates and things like that. > mdadm chooses an amount of space to reserve based roughly on the > size of the device. > It doesn't take into about the chunksize and alignment and so push the > data region to the very end of the device as suggested, though that > would not be particularly hard to do I suspect. It would not be hard to implement but I'm not sure about all the side-effects it has. Some easy ones are: 1. it breaks backwards-compatibility especially in the --assume-clean RAID-reconstruction case 2. it may harm when the array shall be grown in the future (i.e. to bigger components) by means of a reduction of the grown device's netto capacity compared to the unaligned case So if you (or somebody else) intend to do it, please don't make it default. regards Mario -- wenn die nsa spam filtern wuerde... einfach china kappen *** Signoff: Chinah (ix.irc.at linz.irc.at)