Messages in this thread | | | Date | Tue, 16 Feb 2010 17:23:48 +0000 | From | John Robinson <> | Subject | Re: Linux mdadm superblock question. |
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On 16/02/2010 14:37, Volker Armin Hemmann wrote: > On Dienstag 16 Februar 2010, John Robinson wrote: >> On 14/02/2010 19:13, Volker Armin Hemmann wrote: >>> On Sonntag 14 Februar 2010, you wrote: >>>> On 14/02/2010 18:40, Volker Armin Hemmann wrote: >>>>> On Sonntag 14 Februar 2010, you wrote: >>>>>> In other words, 'auto-detection' for 1.x format devices is using an >>>>>> initrd/initramfs. >>>>> which makes 1.x format useless for everybody who does not want to deal >>>>> with initrd/initramfs. >>>> True, but afaik every distro uses an initrd/initramfs and bundles tools >>>> making it easy to manage and customise them, so what's the problem? >>> and distros do it because of all the drivers they have to ship. But for >>> example I am not bound by such limitations. Why should I deal with that? >>> It is hard enough not to forget 'make modules_install'. And now add >>> initrd. Autodetecting just works - but if you use an initrd an it >>> doesn't. Where do you start? >>> >>> Initrd's maybe great for distro packagers, but are they really usefull >>> for anybody else? >> Not just for distro packagers, they're useful for distro users, which >> are presumably 99% of Linux users these days, including the vast >> majority of enterprise users who like tested, supported systems. >> >> But even for people building their own kernels, initrd/initramfs are >> useful if you're using LVM, or indeed trying to boot off anything that's >> not a simple device. > > so assume you have an initrd and metadata 1.x without auto assembling. > > You do some changes to the raid and screw up something else. Next boot nothing > works. Mostly because the mdadm.conf in your initrd is not correct. > > You whip out your trusty usb stick with a resuce system - and you are stuck. > If autoassembling would work, you would have working md devices you could > mount and edit the files you have to. But you don't and the mdadm.conf in the > initrd is outdated. > > Sounds like 'you are screwed'.
No; mdadm can assemble arrays without needing a conf file (at least arrays which have superblocks).
And if you have otherwise screwed something up with the RAID, no amount of in-kernel autoassembly is going to help, in fact it's more likely to get it wrong and make things worse; you need a command line and mdadm to sort it out.
Cheers,
John.
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