Date: Sat, 16 Jan 1999 22:53:23 -0800 (PST) From: Matthew Dillon <dillon@apollo.backplane.com> To: asami@cs.berkeley.edu (Satoshi Asami) Cc: current@FreeBSD.ORG Subject: Re: mounting double-ended SCSI disks Message-ID: <199901170653.WAA47033@apollo.backplane.com>
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:Another problem is if A is mounting it read-only and then B tries to :mount it read-write. This succeeds and is dangerous for the same :reason as the last example. Since A can't write anything to the disk, :I guess there is no way we can avoid this situation. (The only way I :could think of avoiding a crash due to stale cache data was to have A :check the clean flag before every read, but that seems excessively :expensive.) : :Satoshi You have to be able to mount an unclean filesystem read-only -- otherwise the system would not be able to mount root and then fsck it from /etc/rc, nor would you be able to mount a corrupted partition in order to attempt to recover some of it. The clean flag was never designed to handle multi-headed configurations and should not be used for such. The filesystems - even read-only mounts, are also not designed to handle multi-headed configurations. You need a separate mechanism ( like a tcp connection or perhaps you can even use the SCSI reservation stuff manually ) to control access to the filesystems. -Matt Matthew Dillon <dillon@backplane.com> To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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