edward@comp.vuw.ac.nz (Ed Wilkinson) (11/19/87)
We're about to install Ultrix 2.0 & are taking the time to con- sider repartitioning our disk. Currently there are 5 partitions: root, /tmp, /usr, /usr/users and /usr/cs. Unfortunately, this means that we run out of space on one partition or another quite frequently. Thus, we'd like to rearrange the disk to have as few as possible - possibly just a root partition and a users parti- tion. How do other systems setup their disks? If we did have these 2 partitions, we might have to use chpt - I've heard that having non-standard partitions is not a good idea. Is that right? If so, why? BTW, our disk is an RA81 on a Vax 750. Any experiences of repartitioning disks + pros & cons would be most appreciated. Thanks in advance. Please reply via email. -- Ed Wilkinson ...!uunet!vuwcomp!edward or edward@comp.vuw.ac.nz
mbr@aoa.UUCP (Mark Rosenthal) (11/25/87)
In article <13086@comp.vuw.ac.nz> edward@comp.vuw.ac.nz (Ed Wilkinson) writes: >We're about to install Ultrix 2.0 & are taking the time to con- >sider repartitioning our disk. . . . >If we did have >these 2 partitions, we might have to use chpt - I've heard that >having non-standard partitions is not a good idea. Is that right? >If so, why? BTW, our disk is an RA81 on a Vax 750. I installed Ultrix 2.0 on our 8650 last July. The partitioning was one of the most annoying problems. I already had non-standard partition sizes on drive 0, which I was using with Ultrix 1.2. However, the installation script insisted on overwriting these with the standard partition sizes. I was able to re-create my old non-standard partition sizes, but it required a lot of shuffling things back and forth between disks. I allowed the installation script to do its thing, and create a system on drive 0 with standard size partitions. I used this system to create a minimal system on drive 1. This allowed me to boot a system from drive 1 which did not depend on anything on drive 0. (Actually, this took a few tries because I forgot to change the config file to make the kernel swap on drive 1. Oops.) Having done this, I could use chpt to change partitions on drive 0 and not have to worry about depending on data coming from partitions of the disk I was trying to repartition. After this, I restored drive 0 from backup tapes. A related problem is the fact that chpt will allow you to increase the size of the 'a' partition, but will not allow you to decrease it. Nowhere could I find this documented. And the error message is (I don't remember exactly; it's been a while) something like "invalid partition size", which did not necessarily lead me to suspect that there is a special restriction on how you can change partition sizes on drive 'a'. Once I had this explained to me by the people at the Ultrix support line, I came up with a kludge which gets around this. Write a small C program which outputs 1K bytes of zeroes and run it with standard output redirected to the partition 'a' of the raw disk device, e.g. /dev/rra1a. This will clobber the partition table on the disk. The next time you run chpt, it will think it is looking at an uninitialized disk, and will happily change the partition sizes to anything which will fit on the disk. -- Mark of the Valley of Roses ...!{harvard,ima}!bbn!aoa!mbr