From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Accetta Subject: Re: RAID1, hot-swap and boot integrity Date: Mon, 05 Mar 2007 18:38:17 -0500 Message-ID: <45ECA9E9.3090507@laurelnetworks.com> References: <45E82EF8.9000106@laurelnetworks.com> <12470.45E88FAA.5020106@tmr.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <12470.45E88FAA.5020106@tmr.com> Sender: linux-raid-owner@vger.kernel.org To: Bill Davidsen Cc: linux-raid@vger.kernel.org List-Id: linux-raid.ids Bill Davidsen wrote: > Gabor Gombas wrote: >> On Fri, Mar 02, 2007 at 09:04:40AM -0500, Mike Accetta wrote: >> >> >>> Thoughts or other suggestions anyone? >>> >> >> This is a case where a very small /boot partition is still a very good >> idea... 50-100MB is a good choice (some initramfs generators require >> quite a bit of space under /boot while generating the initramfs image >> esp. if you use distro-provided >> "contains-everything-and-the-kitchen-sink" >> kernels, so it is not wise to make /boot _too_ small). >> > You are exactly right on that! Some (many) BIOS implementations will > read the boot sector off the drive, and if there is no error will run > the boot sector. >> But if you do not want /boot to be separate a moderately sized root >> partition is equally good. What you want to avoid is the "whole disk is >> a single partition/file system" kind of setup. >> >> > Actually, the solution is moderately simple, install the replacement > drive, create the partitions, and **don't mark the boot partition > active** until the copy is complete. The BIOS will boot from the 1st > active partition it finds (again, in sane cases). > > I never have anything changing in /boot in normal operation, so I admit > to using dd to do a copy with the array stopped. No particular reason to > think it works better than just a rebuild. After the partition is valid > I set the active flag in the partition. > I gathered the impression somewhere, perhaps incorrectly, that the active flag was a function of the boot block, not the BIOS. We use Grub in the MBR and don't even have an active flag set in the partition table. The system still boots. -- Mike Accetta ECI Telecom Ltd. Data Networking Division (previously Laurel Networks)