Date: Fri, 4 Mar 2011 06:00:15 -0800 From: Jeremy Chadwick <freebsd@jdc.parodius.com> To: Dr Josef Karthauser <joe@tao.org.uk> Cc: Tom Evans <tevans.uk@googlemail.com>, freebsd-fs@freebsd.org Subject: Re: ZFS on a single disk? Message-ID: <20110304140015.GA27523@icarus.home.lan> In-Reply-To: <0A0632A0-24C3-4B11-8542-37A58DCA6390@tao.org.uk> References: <0E00DAFC-C39F-47DC-B9AF-16419C20997F@tao.org.uk> <615F1346-E830-42E2-B229-4181B8BC56BD@exonetric.com> <53FA69D2-2EF0-4CBF-985B-6E710F15FE02@tao.org.uk> <20110302001650.GB49147@icarus.home.lan> <27423168-85BE-41B1-8E14-94F01310EFE4@tao.org.uk> <20110302121612.GA61020@icarus.home.lan> <9EAE56CB-0CE9-4A08-B783-3EF9B1059E62@tao.org.uk> <AANLkTinp5-kHGePPtyiruxKVhWcioRrGwMAYe%2BygK76M@mail.gmail.com> <20110304131849.GA26774@icarus.home.lan> <0A0632A0-24C3-4B11-8542-37A58DCA6390@tao.org.uk>
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On Fri, Mar 04, 2011 at 01:49:15PM +0000, Dr Josef Karthauser wrote: > On 4 Mar 2011, at 13:18, Jeremy Chadwick wrote: > > > > Not to mention, as I understand it, PAE induces all *sorts* of driver > > incompatibilities and technical hurdles when it comes to the kernel. I > > believe there are features/drivers/etc. which also do not build/work if > > PAE is used in the kernel. If something suddenly starts acting "oddly" > > on a PAE system, it wouldn't surprise me if PAE was to blame. > > > > Joe should be aware that amd64 does offer i386 compatibility libraries > > (referred to as "lib32") so you definitely can run i386 binaries on > > amd64. > > Hey Jeremy, > > I don't believe that that's an issue anymore. The XEN kernel comes > configured with PAE as a default option, and I've seen elsewhere that > there is no technical problems running ZFS in a PAE environment. (The > PAE docs are out of date when they say we can't use kernel modules, > and any 64 bit aware kernel model should run with PAE with no > difficulties). XEN isn't something I'm familiar with, which is obviously a huge part of the problem with me trying to give you advice on the matter. :-) The only virtualisation "system" I'm familiar with is VMware Workstation, which isn't anything like XEN. What I'm going off of is /sys/i386/conf/PAE vs. /sys/i386/conf/XEN. Be sure to notice all the "nodevice" lines in /sys/i386/conf/PAE, and the comment directly above those. The XEN configuration file has "options PAE", which is ultimately what a driver/piece of kernel code would use for compile-time detection for supporting/working under PAE. For example, arcmsr(4) will flat out panic() (intentionally) if PAE is used. bge(4) and twa(4) appear to have a 4GB boundary on DMA; I don't know the implications of this. -- | Jeremy Chadwick jdc@parodius.com | | Parodius Networking http://www.parodius.com/ | | UNIX Systems Administrator Mountain View, CA, USA | | Making life hard for others since 1977. PGP 4BD6C0CB |
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