kneifel@bnlux1.bnl.gov (Charley Kneifel) (05/03/91)
Hello,
We just got a Fujitsu M2263 SCSI drive to hook up to a DS3100
running Ultrix (currently 3.1, going to 4.1 next week). I am able to
format the disk using the rzdisk utility and have mounted it
successfully. I made a guess at the disktab entry from the hardware
manual. I have two problems. The first is that the disk uses 512
byte blocks which gives me a formatted capacity of 671.9 MB, which is
what mkfs thinks is there. The docs say that the capacity can be
704.5 MB if I format with a 1 Kb block size. RZ disk would not let me
change the block size parameter. The second problem is that even though
mksees a 671.9 MB disk, the largest size I can see if 628.4 MB. If
I change the disktab entry I can get it as high as 631 MB which was
hardly worth the effort. This is using the c partition which should
be the entire disk.
Here is my disktab entry:
m2263|M2263|M2263S Fujitsu:\
:ty=winchester:ns#54:nt#15:nc#1632:\
pa#32768:ba#8192:fa#1024:\
pb#131072:bb#8192:fb#1024:\
pc#1312300:bc#8192:fc#1024:\
pd#382820:bd#8192:fd#1024:\
pe#382820:be#8192:fe#1024:\
pf#382820:bf#8192:ff#1024:\
pg#1148460:bg#8192:fg#1024:
Are there any archive sites which have a listing of disktab entries for
the major disk manufacturers? I search through the archive database
at McGill with no success. Does anyone have any recommendations for
books which describe the magic neccesary for disktab configuration?
Any and all help is greatly appreciated.
Charley
(kneifel@bnlux1.bnl.gov) or
(kneifel@atoms.chem.sunysb.edu)se@snert.ikp (Stefan Esser) (05/05/91)
In article <1991May3.162032.5909@bnlux1.bnl.gov>, kneifel@bnlux1.bnl.gov (Charley Kneifel) writes: |> Hello, |> |> We just got a Fujitsu M2263 SCSI drive to hook up to a DS3100 |> running Ultrix (currently 3.1, going to 4.1 next week). I am able to |> format the disk using the rzdisk utility and have mounted it |> successfully. I made a guess at the disktab entry from the hardware |> manual. |> Here is my disktab entry: |> |> m2263|M2263|M2263S Fujitsu:\ |> :ty=winchester:ns#54:nt#15:nc#1632:\ |> pa#32768:ba#8192:fa#1024:\ |> pb#131072:bb#8192:fb#1024:\ |> pc#1312300:bc#8192:fc#1024:\ |> pd#382820:bd#8192:fd#1024:\ |> pe#382820:be#8192:fe#1024:\ |> pf#382820:bf#8192:ff#1024:\ |> pg#1148460:bg#8192:fg#1024: Your hardware manual seems a bit different from mine, here are the values for my M2263 (partitions except 'c' deleted ...): m2263|M2263|Fujitsu M2263 (660 MByte):\ :ty=winchester:ns#53:nt#15:nc#1657:\ :pc#1312344:bc#8192:fc#1024: The manual says: 53 sectors per track 15 heads 3 reserved sectors per cylinder (for bad block replacement) 1658 tracks 1 reserved cylinder (for bad block replacement) ==> (53 * 15) - 3 = 792 sectors per cylinder (1658 - 1) * 792 = 1312344 sectors of 512 bytes = 656172 KByte One problem with this is, that the Berkeley Fast File System expects the same number of sectors on each track of a cylinder. But SCSI drives usually have some number of alternate sectors on the last track of each cylinder. The M2263 typically uses sector 1 to 53 on heads 1 to 14 for data storage, but only sector 1 to 50 on head 15 ! That's the reason you can't simply multiply 'SecPerTrk * Heads * Cyl' when calculating the capacity of SCSI disks. (And that's the reason, newfs will complain about unused blocks in the last cylinder of the partitions. The partitions will become multiples of 795 sectors, while the disk size is a multiple of 792 sectors ...) There is another problem with 'Heads * SecPerTrk != SecPerCyl', because the Berkeley FFS expects just this, when allocating blocks for new files. That makes the file layout policies of Ultrix choose rotationally distant blocks, after the disk has been used for a while. This is also a result of other 'features' of SCSI (track skew, cylinder skew). I've made a patch to the file system to avoid this problems, but I think its to much trouble for the average owner of a workstation. I think that Sun has made the necessary changes to the file system to make good use of SCSI disks, but on Ultrix (even 4.1) the file system doesn't know of the special features of SCSI disks. Stefan -- Stefan Esser, Institute of Nuclear Physics, University of Cologne, W. Germany se@ikp.Uni-Koeln.DE [134.95.192.9]