Date: Wed, 05 Dec 2001 20:40:31 -0800 From: Terry Lambert <tlambert2@mindspring.com> To: Brooks Davis <brooks@one-eyed-alien.net> Cc: hackers@freebsd.org Subject: Re: marking disks Message-ID: <3C0EF6BF.743D0E96@mindspring.com> References: <20011204175626.A21463@Odin.AC.HMC.Edu> <3C0DD6CB.F76666D0@mindspring.com> <20011205111236.B21593@Odin.AC.HMC.Edu>
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Brooks Davis wrote: > > It would be easiest for you to create a partition table on the > > disk, and steal a table entry with a "magic" partition type to > > indicate that either the LBA or CHS data was actually version or > > type information, etc.. > > The thing I'm worried about there is that some "smart" bios or os might > sanity check the values and refuse to work with the drive. Is that a > likely scenerio? As long as you never marked the entry active, or ever used the data in it for other than your "magic" application, I don't see a problem. The BIOS only cares about active partitions, and then only when it is trying to boot ffrom them. If you want to play it safe, use entry #4 (if it's free) instead of entry #1 (option base 1). I have seen a number of RAID products that used partition table entries for stripe set identifiers before. While it's theoretically possible for something to care about it, it's incredibly unlikely. New partition types happen all the time, and most partition types are "spoken for". At a bare minimum, you should be able to use a very old partition type, make it valid, and then use the LBA fields (32 bit sector offset and length) to save your data, since very old things like the original FAT types, never referenced those fields at all. If you plan on hacking up fdisk, please teach it about partition type 27 (decimal), which is "Partition Magic". It doesn't affect its operation or FreeBSD's ability to mount the things as FAT32 drives, but it is moderately annoying to see "unknown" out there... 8^). -- Terry To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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