aw@doc.ic.ac.uk (Andrew Weeks) (11/14/88)
We have recently received a new 4.3 Vax release from MtXinu, which contains a disk-labelling system (probably that from 4.3-tahoe). The question I want to ask is, will writing a label onto the disc affect the file system? i.e. can I label a `live' disc, or should I only label a blank disc which I am then going to restore onto? The documentation we have doesn't say anything about this, which probably means it's safe, but then the label must take up some space, where can it get it except at the expense of files?
chris@mimsy.UUCP (Chris Torek) (11/19/88)
In article <498@gould.doc.ic.ac.uk> aw@doc.ic.ac.uk (Andrew Weeks) writes: >The question I want to ask is, will writing a label onto the disc affect >the file system? i.e. can I label a `live' disc, or should I only label >a blank disc which I am then going to restore onto? You can label disks% that are in use, as long as the new label does not move or resize partitions that are in use (the latter may or may not be enforced by the kernel: it has changed on and off during development of the labelling drivers). ----- % For some reason, while a Frisbee is a `disc', a Winchester drive is a `disk' :-) ----- >The documentation we have doesn't say anything about this, which >probably means it's safe, but then the label must take up some space, >where can it get it except at the expense of files? The label resides on sector zero, after (or in the middle of) the level zero bootstrap code. The label can be anywhere within sector 0, but is normally at offset 64 (bytes). -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris
mouse@mcgill-vision.UUCP (der Mouse) (12/02/88)
In article <498@gould.doc.ic.ac.uk>, aw@doc.ic.ac.uk (Andrew Weeks) writes: > We have recently received a new 4.3 Vax release from MtXinu, which > contains a disk-labelling system (probably that from 4.3-tahoe). > [...] but then the label must take up some space, where can it get it > except at the expense of files? The label won't take more than fifty or a hundred bytes, and for something that small there's lots of room floating around, like at the end of the superblock, or maybe inode 0 or 1.... der Mouse old: mcgill-vision!mouse new: mouse@larry.mcrcim.mcgill.edu
chris@mimsy.UUCP (Chris Torek) (12/02/88)
In article <1372@mcgill-vision.UUCP> mouse@mcgill-vision.UUCP (der Mouse) writes: >The label won't take more than fifty or a hundred bytes .... 4.3tahoe disk labels are 276 bytes long. (This is one reason 4.3tahoe drivers will not install in 4.3BSD systems: 4.3BSD ioctls cannot pass more than 127 bytes.) -- In-Real-Life: Chris Torek, Univ of MD Comp Sci Dept (+1 301 454 7163) Domain: chris@mimsy.umd.edu Path: uunet!mimsy!chris