On 08 Jun 2002 07:51:25 +0100 Alex Hudson <home [at] alexhudson.com> wrote: > On Sat, 2002-06-08 at 00:33, Andrew Basterfield wrote: > > So what would happen if you have devfs and more than 128 (IIRC) SCSI > > disks? > > I would extend the kernel to handle more, just like RedHat do now, and > did previously when the limit was 16. And then you hope Linus doesn't allocate your new SCSI block numbers elsewhere. Redhat can get away with this because they have a huge amount of influence on Linux development. > > If you mount a filesystems using NFS it will have no associated /dev > > entry (and hence no majors and minors). > > That argument doesn't follow, I'm afraid. I'm pretty sure NFS clients > get their device numbers from the server - which is why, if you move > an export from one filesystem to another, all the clients need to > remount. So does it return the device number from the server (in which case if the server returns block-8-1 how does it differentiate between /dev/sda1 mounted via NFS and local /dev/sda1) or does it return a unique number (which would require a major/minor allocation space which NFS filesystems don't have in linux/Documentation/devices.txt)? I believe NFS mounted filesystems don't have conventional device numbers. > > This doesn't seem to bother 'find' (or indeed any other POSIX > > utility). > > Really. From the FAQ: > > "Please note that using dynamically allocated block device numbers may > break the NFS daemons [when the numbers change]" (see above :) > > If the NFS daemons break, I suspect very much that the file utilities > will also not work. The point was that 'find' seemed to be perfectly happy on an NFS filesystem (assuming they have no associated major/minor number) as do all other POSIX utilities (in fact they have to work in case / is on NFS). > all that means is that you can't pre-encode the major/minor numbers > you're interested in (both kernel-side or client-side). You can still pre-encode [force] block numbers kernel-side with devfs, should you want to. You have never had the option of pre-encoding the block numbers in userland [client-side??]. --Andrew -- sparc sun4c stuff: http://www.lostgeneration.freeserve.co.uk/sparc PGP key for list [at] lostgeneration.freeserve.co.uk: http://www.lostgeneration.freeserve.co.uk/list.freeserve.co.uk.asc
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