From mboxrd@z Thu Jan 1 00:00:00 1970 From: Neil Brown Subject: Re: Time to deprecate old RAID formats? Date: Fri, 26 Oct 2007 16:16:29 +1000 Message-ID: <18209.34365.375059.602828@notabene.brown> References: <18200.49267.763509.924873@stoffel.org> <18200.53593.687483.120827@stoffel.org> <1192810534.1666.68.camel@firewall.xsintricity.com> <18200.56684.14194.630264@stoffel.org> <1192813877.1666.79.camel@firewall.xsintricity.com> <18200.63987.514073.184865@stoffel.org> <471E7DC6.7050206@tmr.com> <1193184555.10336.3.camel@firewall.xsintricity.com> <18207.56169.769976.512617@notabene.brown> <471FDEB1.8040401@garzik.org> <47204F45.4010205@dgreaves.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: message from David Greaves on Thursday October 25 Sender: linux-raid-owner@vger.kernel.org To: David Greaves Cc: Jeff Garzik , Doug Ledford , Bill Davidsen , John Stoffel , Justin Piszcz , linux-raid@vger.kernel.org List-Id: linux-raid.ids On Thursday October 25, david@dgreaves.com wrote: > > I didn't get a reply to my suggestion of separating the data and location... No. Sorry. > > ie not talking about superblock versions 0.9, 1.0, 1.1, 1.2 etc but a data > format (0.9 vs 1.0) and a location (end,start,offset4k)? > > This would certainly make things a lot clearer to new (and old!) users: > > mdadm --create /dev/md0 --metadata 1.0 --meta-location offset4k > or > mdadm --create /dev/md0 --metadata 1.0 --meta-location start > or > mdadm --create /dev/md0 --metadata 1.0 --meta-location end I'm happy to support synonyms. How about --metadata 1-end --metadata 1-start ?? > > resulting in: > mdadm --detail /dev/md0 > > /dev/md0: > Version : 01.0 > Metadata-locn : End-of-device It already lists the superblock location as a sector offset, but I don't have a problem with reporting: Version : 1.0 (metadata at end of device) Version : 1.1 (metadata at start of device) Would that help? > Creation Time : Fri Aug 4 23:05:02 2006 > Raid Level : raid0 > > You provide rational defaults for mortals and this approach allows people like > Doug to do wacky HA things explicitly. > > I'm not sure you need any changes to the kernel code - probably just the docs > and mdadm. True. > > >> It is conceivable that I could change the default, though that would > >> require a decision as to what the new default would be. I think it > >> would have to be 1.0 or it would cause too much confusion. > > > > A newer default would be nice. > > I also suspect that a *lot* of people will assume that the highest superblock > version is the best and should be used for new installs etc. Grumble... why can't people expect what I want them to expect? > > So if you make 1.0 the default then how many users will try 'the bleeding edge' > and use 1.2? So then you have 1.3 which is the same as 1.0? Hmmmm? So to quote > from an old Soap: "Confused, you will be..." :-) NeilBrown