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 manual 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
appropriate headers and a test pattern and then checking the sector by reading 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 too many 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 forward-
ing table is written to the disk in the first five even numbered sectors of the last track. It is also possible to reformat sections of
the disk in units of tracks. Format may be used on any UNIBUS or MASSBUS drive supported by the up and hp device drivers which uses 4-byte
headers (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 used.
Format also has an option to perform an extended "severe burn-in," which makes a number of passes using different patterns. The number of
passes can be selected at run time, up to a maximum of 48, with provision for additional passes or termination after the preselected number
of passes. This test runs for many hours, depending on the disk and processor.
Each time format is run to format an entire disk, a completely new bad sector table is generated based on errors encountered while format-
ting. The device driver, however, 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 formatted; while ``up(10,0)'' indicates that UNIBUS drive 2 on
UNIBUS adaptor 1 should be formatted.
Before each formatting attempt, format prompts the user in case debugging 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 that all sectors with uncorrectable media errors are
remapped. If a drive develops uncorrectable defects after formatting, either bad144(8) or badsect(8) should be able to avoid the bad sec-
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 with boot(8) following a "B/3" command. 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 (up to 48 passes)
Pattern (one of the above, other to restart)? 2
Maximum number of bit errors to allow for soft ECC(3):
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...)
Bad sector: 0
Write check: 4
Hard ECC: 0
Other hard: 0
Marked bad: 0
Total of 4 hard errors revectored.
Writing bad sector table at block 808272
(808272 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 formatting. 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 drive.
bad144(8), badsect(8), newfs(8)
An equivalent facility should be available which operates under a running UNIX system.
It should be possible to reformat or verify part or all of a disk, then update the existing bad sector table.
4th Berkeley Distribution May 22, 1986 FORMAT(8V)