[comp.sys.sun] Disks space under SunOS 4.1

lidl@eng.umd.edu (Kurt J. Lidl) (07/08/90)

I had a small problem setting up and formatting a Wren-III 91 megabyte
drive under SunOS 4.1.  To be short about it, some of the disk space
disappeared.  Any pointers would be appreciated.

# newfs /dev/rsd4c
/dev/rsd4c:     178350 sectors in 870 cylinders of 5 tracks, 41 sectors
        91.3MB in 55 cyl groups (16 c/g, 1.68MB/g, 768 i/g)
super-block backups (for fsck -b #) at:
 32, 3360, 6688, 10016, 13344, 16672, 20000, 23328, 26272,
 [etc...]
 177440,

#mount /dev/sd4c /mnt
#df /mnt
Filesystem            kbytes    used   avail capacity  Mounted on
/dev/sd4c              82998       9   74689     0%    /mnt

What happened to that 9 megabytes of space that newfs reported on being
there and wasn't after I mounted the partition?  There is a ten percent
differnce between the kbytes/avail columns from "df", but that is to be
expected using the Berkeley FFS.  Where did the space go between the newfs
and the df?  (Thanks in advance!)

/* Kurt J. Lidl (lidl@eng.umd.edu) | Unix is the answer, but only if you */
/* UUCP: uunet!eng.umd.edu!lidl    | phrase the question very carefully. */

smart@hp-sde.sde.hp.com (07/18/90)

| # newfs /dev/rsd4c
| /dev/rsd4c:     178350 sectors in 870 cylinders of 5 tracks, 41 sectors
|       91.3MB in 55 cyl groups (16 c/g, 1.68MB/g, 768 i/g)
| super-block backups (for fsck -b #) at:
|  32, 3360, 6688, 10016, 13344, 16672, 20000, 23328, 26272,
|  [etc...]
|  177440,
| 
| #mount /dev/sd4c /mnt
| #df /mnt
| Filesystem            kbytes    used   avail capacity  Mounted on
| /dev/sd4c              82998       9   74689     0%    /mnt
| 
| What happened to that 9 megabytes of space that newfs reported on being
| there and wasn't after I mounted the partition?  There is a ten percent
| differnce between the kbytes/avail columns from "df", but that is to be
| expected using the Berkeley FFS.  Where did the space go between the newfs
| and the df?  (Thanks in advance!)

  You really didn't lose any space.... the newfs output show Millions of
  Bytes, not MegaBytes -- ie.
      178350 sectors * 512 bytes/sector = 91315200 bytes
         which is  91.3 Millions of Bytes 
            (where Millions of Bytes = 1000 bytes * 1000 bytes)
         OR
         which is  89175 K bytes   
            (where 1 K = 1024 bytes)
            (any data lost here is filesystem overhead)
         OR
         which is  87.1 MegaBytes 
            (where MegaByte = 1024 bytes * 1024 bytes)

  Ultimately, the marketting people had their say when it came to the
  battle over what MB really means......