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[83.79.133.54]) by mx.google.com with ESMTPS id e2sm106627794eeo.8.2013.01.03.14.00.59 (version=TLSv1/SSLv3 cipher=OTHER); Thu, 03 Jan 2013 14:01:00 -0800 (PST) Message-ID: <50E5FF99.4040507@gmail.com> Date: Thu, 03 Jan 2013 23:00:57 +0100 From: =?UTF-8?B?VmxhZGltaXIgJ8+GLWNvZGVyL3BoY29kZXInIFNlcmJpbmVua28=?= User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:10.0.11) Gecko/20121122 Icedove/10.0.11 MIME-Version: 1.0 To: grub-devel@gnu.org Subject: Re: bootable RAID, number of member disks limitation References: <23B0E78D-7EF4-46B4-85EA-5986CCD4E157@colorremedies.com> In-Reply-To: <23B0E78D-7EF4-46B4-85EA-5986CCD4E157@colorremedies.com> X-Enigmail-Version: 1.4.1 Content-Type: multipart/signed; micalg=pgp-sha512; protocol="application/pgp-signature"; boundary="------------enig13BBEE6F2CE205BCC16859D1" X-detected-operating-system: by eggs.gnu.org: GNU/Linux 3.x [fuzzy] X-Received-From: 74.125.83.46 X-BeenThere: grub-devel@gnu.org X-Mailman-Version: 2.1.14 Precedence: list Reply-To: The development of GNU GRUB List-Id: The development of GNU GRUB List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Thu, 03 Jan 2013 22:01:05 -0000 This is an OpenPGP/MIME signed message (RFC 2440 and 3156) --------------enig13BBEE6F2CE205BCC16859D1 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: quoted-printable On 03.01.2013 21:28, Chris Murphy wrote: > I'm finding GRUB2 will boot from md RAID 0, 1, 4, 5, 6, with /boot in t= he array, up to six member devices. At device 7, GRUB2 fails to boot the = array, drops to a grub rescue prompt saying the mduuid couldn't be found.= >=20 > With Btrfs single and RAID 0 profiles, /boot on Btrfs is bootable for u= p to 4 devices. At the 5th device in a volume, it's no longer bootable by= GRUB2, I get a grub rescue prompt. I get variable results with RAID 10 f= or some reason where often it works with 5 and 6 disks. >=20 > The question is if this is expected, as-designed, and if it's stable? I= feel like some subjective (certainly objective limits are OK) limit for = number of member devices is acceptable, but needs to be known, so that in= stallers can inhibit or warn users from creating unbootable arrays. And t= hen how to communicate this downstream? GRUB has no limitation on number on devices other than free memory to hold structures and 2^32 for IDs. If there is any other limit it's a bug and please file a bug report with the images in question (no need to install, just use grub-fstest) However BIOS limits the number of disks that can be accessed. Theoretically there could be up to 128 (or 256 if you use floppy numbers as well) accessible through BIOS. The convention is to use only 16 possible IDs for HDD (0x80-0x8f). In practice many BIOSes are limited to less (8 is usual limit). >=20 >=20 > Chris Murphy > _______________________________________________ > Grub-devel mailing list > Grub-devel@gnu.org > https://lists.gnu.org/mailman/listinfo/grub-devel >=20 --=20 Regards Vladimir '=CF=86-coder/phcoder' Serbinenko --------------enig13BBEE6F2CE205BCC16859D1 Content-Type: application/pgp-signature; name="signature.asc" Content-Description: OpenPGP digital signature Content-Disposition: attachment; filename="signature.asc" -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.12 (GNU/Linux) Comment: Using GnuPG with Mozilla - http://enigmail.mozdev.org/ iF4EAREKAAYFAlDl/5oACgkQNak7dOguQgnhmgEAmvCucCA9S4VVrYoF1JZq+rTR rIi01pnPl0rZef/yVUABAITGvUlH3DELfB+bAOC0J5hagcmvtL6Ix6sLTLCPZ8Z1 =RSW4 -----END PGP SIGNATURE----- --------------enig13BBEE6F2CE205BCC16859D1--