marselle@research.att.com (03/14/89)
I've got a question about formatting new disks and creating file systems on them. I have a Sun-3/140 with a Ciprico Rimfire 3200 disk controller which serves one diskless Sun-3/50 client now, and will serve 4 more soon (when we get them). I have successfully formatted and partitioned the disk (a Fujitsu 2344) following some local advice and some Ciprico and Sun documentation. However, there are a few places where my knowledge is fuzzy and I can't seem to find any documentation to clear up the confusion. Perhaps this is in the realm of Unix "folklore" and someone in net-land can help (pointers to articles, books, etc. would also be appreciated). My first question concerns the b: partition on the drive, which I understand is the swap partition. Is the b: partition always the swap partition? Is this a Unix convention? How large should it be? Mine is 18 Mbytes. Is there a rule of thumb for estimating the size of the swap partition? Next, what about the space allocated for the /export file system? Is there a rule of thumb that says that for n diskless clients, you need x=f(n) Mbytes of space in the partition which will be used for the /export file system? We use 16 Mbytes for the swap space for each client, which lives in /export/swap/<hostname>. There's also space required to hold each client's root file system, in /export/root/<hostname>. Is there an estimate for this space? On one of our other systems, I see this range from 3500 blocks to 1700 blocks for various clients. I'd rather not play a guessing game and end up wasting a lot of space if I overestimate, or have to re-partition if I underestimate. Another thing I've noticed is that when I use "newfs" to make a file system on a partition and then do a "df", the amount of space shown in the "kbytes" column is less than than the amount I expected when I calculated partition sizes. I know that the the "used" plus "avail" amounts are less than the "kbytes" amount to allow for a 10% (default) reserve. For example, I have a /usr file system on my disk which is 264114 512-byte sectors (blocks), which is 135,226,368 bytes. But when I do a "df", this is what I see: Filesystem kbytes used avail capacity Mounted on /dev/rf0d 129320 107194 9194 92% /usr 129320 * 1024 = 132,423,680 bytes, which is less than 135,226,368. What's going on here? Does Unix snarf up some of the space for inodes and/or other stuff? Is there a rule that I can use to allow for this so I don't get squeezed and end up with less space than I need (this happened to me before and I had to re-partition the disk to make the /usr file system larger; but I was just shooting in the dark when I did it). I've been reading the Sun System & Network Administration manual but all I find is an explanation of how to set up the partitions; not how to estimate how large they should be. Jim Marselle AT&T Bell Labs Naperville, IL att!ihlpf!marselle (312) 416-4108