mkhaw@teknowledge-vaxc.ARPA (Michael Khaw) (05/21/87)
Ultrix uses a program called /etc/chpt to set/show the disk partition
tables (on ra81's, anyway). Hidden away in the system administrator's
guide to disk partitioning is a note that:
- a disk MUST have an "a" partition with a filesystem
on it (unless you want to use the default partition
tables built into the device driver)
- you can always grow the "a" partition, but it MUST
begin at sector 0 and once set to a certain size, it
cannot be made smaller.
Why?
Mike Khaw
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USnail: Teknowledge Inc, 1850 Embarcadero Rd, POB 10119, Palo Alto, CA 94303mkhaw@teknowledge-vaxc.ARPA (Michael Khaw) (05/21/87)
I forgot to add that my system runs Ultrix 1.2
To expand a bit more, what if I make the "b" partition *partially* overlap
the "a" partition, and use /etc/newfs to build a 1-cylinder filesystem on
"a" and use "b" for swapping/paging -- am I asking for trouble?
Mike Khaw
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USnail: Teknowledge Inc, 1850 Embarcadero Rd, POB 10119, Palo Alto, CA 94303ems@apple.UUCP (Mike Smith) (06/02/87)
In article <12963@teknowledge-vaxc.ARPA>, mkhaw@teknowledge-vaxc.ARPA (Michael Khaw) writes: > Ultrix uses a program called /etc/chpt to set/show the disk partition > tables (on ra81's, anyway). Hidden away in the system administrator's > guide to disk partitioning is a note that: > > - a disk MUST have an "a" partition with a filesystem > on it (unless you want to use the default partition > tables built into the device driver) > - you can always grow the "a" partition, but it MUST > begin at sector 0 and once set to a certain size, it > cannot be made smaller. One can also cheat and just use a 'c' partition. This makes the whole pack a single filesystem. It seems that since the 'c' partition starts where the 'a' partition starts, it is properly handled. Makes a mighty big partition, though. -- E. Michael Smith ...!sun!apple!ems 'If you can dream it, you can do it' Walt Disney This is the obligatory disclaimer of everything. (Including but not limited to: typos, spelling, diction, logic, and nuclear war)
mkhaw@teknowledge-vaxc.UUCP (06/02/87)
In article <903@apple.UUCP> ems@apple.UUCP (Mike Smith) writes: ]In article <12963@teknowledge-vaxc.ARPA>, mkhaw@teknowledge-vaxc.ARPA (Michael Khaw) writes: ]> Ultrix uses a program called /etc/chpt to set/show the disk partition ]> tables (on ra81's, anyway). Hidden away in the system administrator's ]> guide to disk partitioning is a note that: ]> ]> - a disk MUST have an "a" partition with a filesystem ]> on it (unless you want to use the default partition ]> tables built into the device driver) ]> - you can always grow the "a" partition, but it MUST ]> begin at sector 0 and once set to a certain size, it ]> cannot be made smaller. ] ]One can also cheat and just use a 'c' partition. This makes the whole pack ]a single filesystem. It seems that since the 'c' partition starts where the ]'a' partition starts, it is properly handled. Makes a mighty big partition, ]though. What if I cheat and tell newfs that the "a" partition is, say, only 1 cylinder, and make the b partition start at the second (or do you count from zero and call it the first) cylinder? Will that fly if I use "b" for swapping? What I'm really trying to get at is I want a "b" swap partition near the "front" of the disk, and a fairly large "h" partition "behind" it, but I don't want to waste the 7 odd Mb "a" partition, so can I make "b" overlap with "a" if I tell newfs that "a" is only the part that doesn't overlap "b"? Mike Khaw -- internet: mkhaw@teknowledge-vaxc.arpa usenet: {hplabs|sun|ucbvax|decwrl|sri-unix}!mkhaw%teknowledge-vaxc.arpa USnail: Teknowledge Inc, 1850 Embarcadero Rd, POB 10119, Palo Alto, CA 94303
zemon@felix.UUCP (06/02/87)
In article <12964@teknowledge-vaxc.ARPA> mkhaw@teknowledge-vaxc.UUCP (Michael Khaw) writes: >I forgot to add that my system runs Ultrix 1.2 > >To expand a bit more, what if I make the "b" partition *partially* overlap >the "a" partition, and use /etc/newfs to build a 1-cylinder filesystem on >"a" and use "b" for swapping/paging -- am I asking for trouble? > >Mike Khaw We are running Ultrix 2.0 and I have had no trouble placing a raw database partition in a chunk of disk that partially overlays partition a. I build a file system on partition a so there would be a valid superblock, built my partition tabke with /etc/chpt, and then proceded to clobber most of the file system with my DBMS. Since I never mess with the file system and the DBMS cannot overwrite the partition table at the beginning, all is well. -- Art Z. -- -- Art Zemon FileNet Corporation Costa Mesa, California ...!hplabs!felix!zemon
ems@apple.UUCP (Mike Smith) (06/03/87)
In article <13263@teknowledge-vaxc.ARPA>, mkhaw@teknowledge-vaxc.ARPA (Michael Khaw) writes: > What I'm really trying to get at is I want a "b" swap partition near the "front" > of the disk, and a fairly large "h" partition "behind" it, but I don't want to > waste the 7 odd Mb "a" partition, so can I make "b" overlap with "a" if I tell > newfs that "a" is only the part that doesn't overlap "b"? Why don't you just do your swaping on the 'a' partition? Have it overlap the b and maybe even the g partition, then have your h. (or combine the g with the h...). Making the small a should also work, but is kind of kludgy... -- E. Michael Smith ...!sun!apple!ems 'If you can dream it, you can do it' Walt Disney This is the obligatory disclaimer of everything. (Including but not limited to: typos, spelling, diction, logic, and nuclear war)
mkhaw@teknowledge-vaxc.UUCP (06/03/87)
In article <912@apple.UUCP> ems@apple.UUCP (Mike Smith) writes: >Why don't you just do your swaping on the 'a' partition? Have it Nope, if I use 'a' for swapping then it doesn't have a filesystem on it, therefore no superblock(s), therefore(?) no partition table. (I already tried). The Ultrix ra81 givens are: - you MUST have an 'a' partition WITH a filesystem on it - the 'a' partition must begin at sector 0 and cannot be made smaller - the default size of the 'a' partition is (approx.) 7 Mbytes But others have said that they overlap 'a' with other partitions and build just a tiny filesystem on 'a'. It IS a kludge, but it seems to be my only option. Mike Khaw -- internet: mkhaw@teknowledge-vaxc.arpa usenet: {hplabs|sun|ucbvax|decwrl|sri-unix}!mkhaw%teknowledge-vaxc.arpa USnail: Teknowledge Inc, 1850 Embarcadero Rd, POB 10119, Palo Alto, CA 94303