23 jan 90 The first step is to determine your drive's name, geometry and available sectors. Right? So, you call your vendor, order the product specification manual, call the manufacturer. Right? Wrong. This got me nowhere. The NeXT comes with a cute little program (/etc/scsimodes) that tells you all you need to know. Disconnect your 40 MB accelerator drive (if you have one) and plug in your Wren V jumpered for SCSI target 0. Boot off the optical drive. Execute scsimodes (no disktab entry is required for scsimodes.) ---------------------------------------------- localhost# scsimodes /dev/rsd0a SCSI information for /dev/rsd0a Drive type: CDC 94181-15 512 bytes per sector 52 sectors per track 15 tracks per cylinder 1546 cylinder per volume (including spare cylinders) 1 spare sectors per track 30 alternate tracks per volume 1173929 usable sectors on volume ------------------------------------------------- Voila! Everything you need to know. The disktab entry must have the appropriate name (CDC 94181-15). Twiddle with nc, nt, ns to get as close as possible to "sectors on volume". (Or just use mine.) With this entry in /etc/disktab you are ready to do a builddisk. The NextStep builddisk utility ran fine. Notice that my partition sizes are an integral number of cylinders each, thus avoiding the "..... xxx sectors unallocated in last cylinder group ..." message from newfs. My raw partitions add up to 586MB, which boil down to 573MB once the inodes are allocated by newfs, which leaves 518MB with a 10% minfree. I don't have any programs to reformat this pup with 1KB sectors, although I suppose an expert with Sun's format program could have gotten some more space by reformatting at 512B/sector and fewer spare sectors. (Imprimis claims maximum raw formatted size is 639MB with 1KB sectors and no spares.) Partition sizes + front porch <= usable sectors on volume (I think, ...what is front porch?) For comparison, the Maxtor 8760S gives the following: ----------------------------------------------- localhost# scsimodes /dev/rsd0a SCSI information for /dev/rsd0a Drive type: MAXTOR XT-8760S 1024 bytes per sector 28 sectors per track 15 tracks per cylinder 1632 cylinder per volume (including spare cylinders) 4 spare sectors per cylinder 45 alternate tracks per volume 676415 usable sectors on volume ---------------------------------------------- Sequential reads with the disk program shows the Maxtor to be slightly faster: MAXTOR disk> read starting block? 0 # sectors per transfer? 16 number of transfers? 1000 sector increment? 16 16384000 bytes in 51996 ms = 315137 bytes/s <<<<<<<<<<<<<<< disk> read starting block? 0 # sectors per transfer? 16 number of transfers? 1000 sector increment? 16 16384000 bytes in 51190 ms = 320062 bytes/s <<<<<<<<<<<<<<<< WREN V disk> read starting block? 0 # sectors per transfer? 16 number of transfers? 1000 sector increment? 16 16384000 bytes in 63871 ms = 256521 bytes/s <<<<<<<<<<<<<<<< disk> read starting block? 0 # sectors per transfer? 16 number of transfers? 1000 sector increment? 16 16384000 bytes in 63471 ms = 258137 bytes/s <<<<<<<<<<<<<< Random seeks with the disk program show the Wren to be slightly faster. (Sorry, no way to show you the graph of seek times.) The Wren is significantly louder during seeking. I've a hunch that the system is not accessing the Wren V optimally. This drive has a 32KB internal data buffer, and sequential reads should really scream. Anyone who can shed light on the cryptic "tuning the file system rotational latency parameter" phrase at the beginning of /etc/disktab; please elucidate. Keep in mind -- the Wren V is 13% smaller than the Maxtor, and 52% cheaper. The hardest part of the whole job was peeling off the Wren's front panel. It's held on with double sided sticky foam. Don't try to undo the folds in the NeXT's SCSI cable. The glue they use is stronger than the flat cable. The cable splits before the glue lets go. Paul O'Neill pvo@oce.orst.edu Coastal Imaging Lab OSU--Oceanography Corvallis, OR 97331 503-754-3251
These are the contents of the former NiCE NeXT User Group NeXTSTEP/OpenStep software archive, currently hosted by Netfuture.ch.