Date: Mon, 23 Jan 2012 11:16:58 -0700 From: Ian Lepore <freebsd@damnhippie.dyndns.org> To: Devin Teske <devin.teske@fisglobal.com> Cc: freebsd-hackers@freebsd.org Subject: Re: Parallels v4 regression (aka ada(4) oddity) in RELENG_9 Message-ID: <1327342618.69022.83.camel@revolution.hippie.lan> In-Reply-To: <009501ccd9f9$cad088d0$60719a70$@fisglobal.com> References: <009501ccd9f9$cad088d0$60719a70$@fisglobal.com>
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On Mon, 2012-01-23 at 10:06 -0800, Devin Teske wrote: > I have a Parallels virtual machine and it runs FreeBSD 4 through 8 just > swimmingly. > > However, in RELENG_9 I notice something different. My once "ad0" is now showing > up as "ada0". However, something even stranger is that devfs is providing both > ad0 family devices AND ada0 family devices. > > What's worse is that I can't seem to partition the disk with MBR+disklabel > scheme. > > My procedure goes something like this: > > 1. Boot from RELENG_9 LiveCD > 2. Execute: sysctl -n kern.disks > 3. Notice two items: cd0 ada0 > 4. Look in /dev > 5. Notice several items: ad0 ad0p1 ad0p2 ad0p3 ada0 ada0p1 ada0p2 ada0p3 > 6. Wipe partition table by executing: dd if=/dev/zero of=/dev/ada0 bs=512k > count=256 > 7. Look in /dev > 8. Notice less items now: ad0 ada0 > 9. Execute: sysctl -n kern.disks > 10. Notice nothing changed: cd0 ada0 > 11. Write out standard "whole disk" MBR "slice" > 12. Look in /dev > 13. Notice that nothing changed: ad0 ada0 > NOTE: Where is ad0s1 or ada0s1? > 14. Use fdisk to make sure everything was written successfully > 15. Notice everything looks good (slice 1 is of type FreeBSD, slice 2, 3, and 4 > are unused) > 16. Reboot > 17. Boot back into RELENG_9 LiveCD > 18. Look in /dev > 19. Notice that the old devices are back!: ad0 ad0p1 ad0p2 ad0p3 ada0 ada0p1 > ada0p2 ada0p3 > 20. Use fstab to look at MBR partition table > 21. Notice that things look good (with respect to fdisk'ing): slice 1 is > FreeBSD, 2, 3, and 4 are still unused > 22. Notice /dev still doesn't have ad0s1 or ada0s1 > 23. Use gpart to look at ada0 > 24. Notice "GPT [CORRUPT]" > > ... > > OK!?!? > > ... > > Use same exact RELENG_9 LiveCD on either a physical machine or VMware Virtual > machine. > > SUCCESS!! > > Go back to Parallels 4 > > FAILURE!! > > Go back to RELENG_8 LiveCD with Parallels 4 > > SUCCESS!! > > What's going on here? I think ada(4) is my problem. Can someone please provide > feedback? Willing to dig further and provide any/all feedback to help fix this > regression. I've experienced the part of that scenario where changing a drive from gpt to mbr scheme results in all the gpt partitions reappearing after a reboot. I concluded (but didn't take time to be absolutely certain) that during boot the geom layer was seeing the backup gpt partition info at the end of the disk and concluding that it needed to ignore the mbr and use the backup gpt info instead. Once I quit using dd and similar tools and consistantly used "gpart destroy" to wipe out the gpt before changing to mbr, it stopped happening. -- Ian
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