From mboxrd@z Thu Jan 1 00:00:00 1970 From: Roman Mamedov Subject: Re: Any pros or cons of using full disk versus partitons? Date: Thu, 14 Apr 2011 14:30:07 +0600 Message-ID: <20110414143007.477e6dcd@natsu> References: <07a801cbfa12$64b8a950$2e29fbf0$@gmail.com> <20110413.132112.102552472.davem@davemloft.net> <20110414181159.48a2086e@notabene.brown> Mime-Version: 1.0 Content-Type: multipart/signed; micalg=PGP-SHA1; boundary="Sig_/EI84oxdiU2KzlsKbHaWKBS5"; protocol="application/pgp-signature" Return-path: In-Reply-To: <20110414181159.48a2086e@notabene.brown> Sender: linux-raid-owner@vger.kernel.org To: NeilBrown Cc: CoolCold , David Brown , linux-raid@vger.kernel.org List-Id: linux-raid.ids --Sig_/EI84oxdiU2KzlsKbHaWKBS5 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: quoted-printable On Thu, 14 Apr 2011 18:11:59 +1000 NeilBrown wrote: > On Thu, 14 Apr 2011 11:57:47 +0400 CoolCold wrote: >=20 > > Just my 2 cents: I've faced problems when newer disk was smaller than > > old disk two or three times, so using partitions now with setting some > > free space at the end - something near 80 or 100 megabytes. There are also some Gigabyte motherboards which like to cut off a small portion of a disk at the end via HPA, and writing a backup of their BIOS th= ere. https://encrypted.google.com/search?q=3Dgigabyte+bios+hpa If you had your user data or mdadm metadata there, bad luck. On earlier motherboards this was done automatically to every new disk on SATA0, on newer ones I think it's optional and can be disabled. But anyway,= I now prefer to leave about 8 MB of space at the end of each drive unpartitioned, just in case. And another point, again related to buggy BIOSes: some of them seem to read first sectors of all attached disks and expect to see an MBR-style partition table there; and if there's something else instead (e.g. basically random data, in case of the whole disk used for RAID), they may become confused and lock-up at boot. I had a couple of such cases where a board would lock-up at HDD detection with a certain drive attached, and would only boot up properly after it was zeroed and repartitioned. >=20 > You don't need partitions to do this. Just use the --size option to mdad= m. But then the 1.x+ metadata is still stored at the very end of the device, which makes it vulnerable to the HPA problem described above. --=20 With respect, Roman --Sig_/EI84oxdiU2KzlsKbHaWKBS5 Content-Type: application/pgp-signature; name=signature.asc Content-Disposition: attachment; filename=signature.asc -----BEGIN PGP SIGNATURE----- Version: GnuPG v1.4.11 (GNU/Linux) iEYEARECAAYFAk2msI8ACgkQTLKSvz+PZwj63ACgh5lGAQiLbTiNbQeVP19I8cCe qqwAn3xwbrJAQUWNv6HnQ+nhqxTGCKVb =hIDH -----END PGP SIGNATURE----- --Sig_/EI84oxdiU2KzlsKbHaWKBS5--