Date: Wed, 23 Jan 2008 09:19:22 -0500 From: John Baldwin <jhb@freebsd.org> To: freebsd-stable@freebsd.org Cc: scottl@freebsd.org, Aldas Nabazas <freebsd.stable1@gmail.com>, ambrisko@freebsd.org, David Wood <david@wood2.org.uk> Subject: Re: Dell Perc 6 disk geometry problem with RAID5 (both 6.3 final and 7.0 RC1) Message-ID: <200801230919.23681.jhb@freebsd.org> In-Reply-To: <35cWA$Gqi5kHFAjh@wood2.org.uk> References: <9c1614e00801200608k49195944mf241b7b0aa6a48@mail.gmail.com> <20080120175819.GA52965@owl.midgard.homeip.net> <35cWA$Gqi5kHFAjh@wood2.org.uk>
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On Sunday 20 January 2008 01:53:30 pm David Wood wrote: > Hi there, > > In message <20080120175819.GA52965@owl.midgard.homeip.net>, Erik > Trulsson <ertr1013@student.uu.se> writes > >On Sun, Jan 20, 2008 at 04:48:56PM +0000, David Wood wrote: > >> In message <9c1614e00801200608k49195944mf241b7b0aa6a48@mail.gmail.com>, > >> Aldas Nabazas <freebsd.stable1@gmail.com> writes > >>> We bought a new Dell PowerEdge 2950III with Perc 6/i and have the disk > >>> geometry problem using 6.3 final or 7.0 RC1. Seems that we are not alone at > >>> least one guy has similar problem reported earlier: > >>> > >>>http://unix.derkeiler.com/Mailing-Lists/FreeBSD/questions/2008-01/msg0 > >>>0506.html > > > >I do not know if the mfi(4) driver has any problems with large disks, but it > >is however well known that fdisk(8) and bsdlabel(8) (the tools normally used > >to partition disks) have problems with volumes larger than 2TB. > > > >If you want to use volumes larger than 2TB then gpt(8) is the recommended > >way to partition the disks. It is however doubtful if the BIOS in your > >system will allow you to boot from a gpt(8) parttioned volume which is > >best solved with having a separate - smaller - boot volume where the OS > >itself is installed. > > Erik's reminder is timely for those with >2TB volumes. > > You must use gpt and not fdisk on any disk, be it a single drive (in the > future, at least!) or a virtual disk on a RAID setup that are bigger > than 2TB. It may be wise to use gpt on any virtual disk that you might > grow to 2TB or larger in the future, so long as you're not needing to > boot from that virtual disk. > > fdisk will not work properly with 2TB and larger volumes - the MBR / > partition table setup can't cope with these large volumes. > > > You can't boot from a GPT volume - that's a limitation of the BIOS > architecture. There is some thought about using EFI on x64 hardware in > the future (EFI is used on ia64 hardware; GPT is part of EFI), but we're > not there yet. This isn't just about adding GPT support to the BIOS - > the whole BIOS setup is wedded to MBR. > > If you need to boot from a >2TB array, create two virtual disks - one > smaller than 2TB to boot from (and use MBR on that), then the residue > can be GPT. Actually, using gptboot in HEAD you can now boot from GPT on large volumes (I've booted from a > 2 TB volume on a PERC5 using mfi(4) with it). I will see about getting that merged back to 6.x and 7.x in CVS. We use it for large volumes on 6.x and all volumes on 7.x at work. > When I said there was nothing relevant waiting for MFC, I was aware of > the change that Tom mentioned, but that seems to be about Dell PERC 6 > being identified as such rather than a MegaRAID. It doesn't seem that it > will change the behaviour of the driver in any way. In our testing at work the 2950 rev 3's worked fine with mfi(4). -- John Baldwin
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