Date: Wed, 19 Nov 2014 15:43:18 +0000 From: "Pokala, Ravi" <rpokala@panasas.com> To: "jose@we.lc.ehu.es" <jose@we.lc.ehu.es>, Borja Marcos <borjam@sarenet.es> Cc: "freebsd-fs@freebsd.org" <freebsd-fs@freebsd.org> Subject: Re: BIOS booting from disks > 2TB Message-ID: <D091F577.12467D%rpokala@panasas.com>
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>Date: Wed, 19 Nov 2014 10:06:43 +0100 >From: Jos? Mar?a Alcaide <jose@we.lc.ehu.es> >To: freebsd-fs@freebsd.org >Subject: Re: BIOS booting from disks > 2TB >Message-ID: <17A2AC72-AD70-480A-9BAC-9CC8EAFD572F@we.lc.ehu.es> >Content-Type: text/plain; charset=3Dus-ascii > >On Nov 19, 2014, at 8:06 AM, Pokala, Ravi wrote: > >> When you perform your installation, just make sure to select the GPT >> option for partitioning. The installer (either `bsdinstall' (for stock >> FreeBSD), or `pc-sysinstall' (for PC-BSD / FreeNAS)) should create both >> primary (near start-of-disk) and backup (at end-of-disk) GPT tables, and >> install the appropriate bootstrap code in the proper locations. >>=20 > >Yes, bsdinstall flawlessly creates both primary and backup GPT tables >even using disks > 2 TB, by virtue of the FreeBSD kernel. The problem >arises at the first stages of booting, when gptboot tries to compare the >primary and backup tables *using the BIOS disk services*, which are not >able to reach anything after the 2 TB limit. As a consequence gptboot >fails, stating that it did not find the GPT backup table. Jos=E9: Ah, I see what you're saying. That sounds reasonable. I never saw those warnings, because the version of the PMBR that I'm using at work is fairly old; it pre-dates the code to check the backup GPT if the primary is invalid [r239060]. The fact that this message is coming up at all means the primary GPT is broken. :-( Borja: I'd try booting from a different device (network, USB), then see if `gpart show' is able to list the partitions on the drive in question. If it is, then the secondary GPT is okay, and you may be able to use `gpart backup' to save out the parsed partition table. You could then use `gpart restore' to re-write the partition table to both primary and backup locations. I say that having never actually *done* it, so proceed with caution, and let us know what happens. Good luck! -Ravi >-- >Jose M. Alcaide
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