format - how to format disk packs
There are two ways to format disk packs. The simplest is to use the
format program. The alternative is to use the DEC standard formatting
software which operates under the DEC diagnostic supervisor. This man-
ual page describes the operation of format, then concludes with some
remarks about using the DEC formatter.
Format is a standalone program used to format and check disks prior to
constructing file systems. In addition to the formatting operation,
format records any bad sectors encountered according to DEC standard
144. Formatting is performed one track at a time by writing the appro-
priate headers and a test pattern and then checking the sector by read-
ing and verifying the pattern, using the controller's ECC for error
detection. A sector is marked bad if an unrecoverable media error is
detected, or if a correctable ECC error greater than 5 bits in length
is detected (such errors are indicated as ``ECC'' in the summary
printed upon completing the format operation). After the entire disk
has been formatted and checked, the total number of errors are
reported, any bad sectors and skip sectors are marked, and a bad sector
forwarding table is written to the disk in the first five even numbered
sectors of the last track. Format may be used on any UNIBUS or MASSBUS
drive supported by the up and hp device drivers which uses 4-byte head-
ers (everything except RP's).
The test pattern used during the media check may be selected from one
of: 0xf00f (RH750 worst case), 0xec6d (media worst case), and 0xa5a5
(alternating 1's and 0's). Normally the media worst case pattern is
Format also has an option to perform an extended "severe burnin," which
makes 46 passes using different patterns. Using this option, sectors
with any errors of any size are marked bad. This test runs for many
hours, depending on the disk and processor.
Each time format is run a completely new bad sector table is generated
based on errors encountered while formatting. The device driver, how-
ever, will always attempt to read any existing bad sector table when
the device is first opened. Thus, if a disk pack has never previously
been formatted, or has been formatted with different sectoring, five
error messages will be printed when the driver attempts to read the bad
sector table; these diagnostics should be ignored.
Formatting a 400 megabyte disk on a MASSBUS disk controller usually
takes about 20 minutes. Formatting on a UNIBUS disk controller takes
significantly longer. For every hundredth cylinder formatted format
prints a message indicating the current cylinder being formatted.
(This message is just to reassure people that nothing is is amiss.)
Format uses the standard notation of the standalone i/o library in
identifying a drive to be formatted. A drive is specified as zz(x,y),
where zz refers to the controller type (either hp or up), x is the unit
number of the drive; 8 times the UNIBUS or MASSBUS adaptor number plus
the MASSBUS drive number or UNIBUS drive unit number; and y is the file
system partition on drive x (this should always be 0). For example,
``hp(1,0)'' indicates that drive 1 on MASSBUS adaptor 0 should be for-
matted; while ``up(10,0)'' indicates UNIBUS drive 2 on UNIBUS adaptor 1
should be formatted.
Before each formatting attempt, format prompts the user in case debug-
ging should be enabled in the appropriate device driver. A carriage
return disables debugging information.
Format should be used prior to building file systems (with newfs(8)) to
insure all sectors with uncorrectable media errors are remapped. If a
drive develops uncorrectable defects after formatting, the program bad-
sect(8) must be used.
A sample run of format is shown below. In this example (using a
VAX-11/780), format is loaded from the console floppy; on an 11/750
format will be loaded from the root file system. Boldface means user
input. As usual, ``#'' and ``@'' may be used to edit input.
LOAD DONE, 00004400 BYTES LOADED
Disk format/check utility
Enable debugging (0=none, 1=bse, 2=ecc, 3=bse+ecc)? 0
Device to format? hp(8,0)
(error messages may occur as old bad sector table is read)
Formatting drive hp0 on adaptor 1: verify (yes/no)? yes
Device data: #cylinders=842, #tracks=20, #sectors=48
Available test patterns are:
1 - (f00f) rh750 worst case
2 - (ec6d) media worst case
3 - (a5a5) alternating 1's and 0's
4 - (ffff) Severe burnin (takes several hours)
Pattern (one of the above, other to restart)? 2
Start formatting...make sure the drive is online
(soft ecc's and other errors are reported as they occur)
(if 4 write check errors were found, the program terminates like this...)
Write check: 4
Bad sector: 0
Skip sector: 0
Total of 4 hard errors found.
Writing bad sector table at block 808271
(808271 is the block # of the first block in the bad sector table)
(...program restarts to allow formatting other disks)
(...to abort halt machine with ^P)
The diagnostics are intended to be self explanatory.
USING DEC SOFTWARE TO FORMAT
Warning: These instructions are for people with 11/780 CPU's. The
steps needed for 11/750 or 11/730 cpu's are similar, but not covered in
The formatting procedures are different for each type of disk. Listed
here are the formatting procedures for RK07's, RP0X, and RM0X disks.
You should shut down UNIX and halt the machine to do any disk format-
ting. Make certain you put in the pack you want formatted. It is also
a good idea to spin down or write protect the disks you don't want to
format, just in case.
Formatting an RK07. Load the console floppy labeled, "RX11 VAX DSK LD
DEV #1" in the console disk drive, and type the following commands:
DIAGNOSTIC SUPERVISOR. ZZ-ESSAA-X5.0-119 23-JAN-1980 12:44:40.03
DS>ATTACH DW780 SBI DW0 3 5
DS>ATTACH RK611 DMA
DS>ATTACH RK07 DW0 DMA0
Formatting an RP0X. Follow the above procedures except that the ATTACH
and SELECT lines should read:
DS>ATTACH RH780 SBI RH0 8 5
DS>ATTACH RP0X RH0 DBA0(RP0X is, e.g. RP06)
This is for drive 0 on mba0; use 9 instead of 8 for mba1, etc.
Formatting an RM0X. Follow the above procedures except that the ATTACH
and SELECT lines should read:
DS>ATTACH RH780 SBI RH0 8 5
DS>ATTACH RM0X RH0 DRA0
Don't forget to put your UNIX console floppy back in the floppy disk
bad144(8), badsect(8), newfs(8)
An equivalent facility should be available which operates under a run-
ning UNIX system.
It should be possible to define more precisely what a ``hard ECC''
error is; e.g. the maximum unacceptable ECC width.
4th Berkeley Distribution 25 February 1983 FORMAT(8V)