182 lines
9.4 KiB
Plaintext
182 lines
9.4 KiB
Plaintext
The program 'minit' creates minixfs filesystems. Then can be created on a
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TOS formatted disk or a TOS filesystem, then can also be created to alter
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the parameters of an already existing minixfs partition.
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WARNING: USING MINIT TO CREATE FILESYSTEMS WILL IRRETRIEVABLY WIPE ALL DATA
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ON THAT PARTITION. This includes using it to create a filesystem 'on top' of
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an already existing one. Don't say I didn't warn you.
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FILESYSTEM VERSIONS.
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Before you decide to make a filesystem you must decide which kind of filesystem
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you want to make. There are two kinds at present V1 and V2. These are
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compatible with the equivalent Minix filesystems. V1 filesystems are the
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standard Minix filesystems used with all versions of Minix, they do have a
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number of shortcomings, there is only one kind of file access time and V1
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filesystems can be at most 64Mb in size. V2 filesystems are newer and are
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the same as the V2 filesystems used by Minix 1.6xx (and presumably higher).
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They have three access times and can be any size (if you hard disk software
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will support it). I would strongly advise the use of V2 filesystems.
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If you supply the -V option to minit you will make a V2 filesystem,
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otherwise it will be V1.
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DIRECTORY INCREMENT
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It doesn't quite end there though. There are a couple more parameters
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you should know about. Under Minix itself you can have filenames of at most
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14 characters in length. Minixfs uses this value by default. However there is
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a parameter called 'directory increment' which allows you to use longer
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filenames. This parameter must be a power of two between 1 and 8 (inclusive)
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in other words it can be 1,2,4 or 8. The maximum filename size is given by
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the formula maxlength= increment*16 - 2. Thus increments of 1,2,4,8 will
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result in maximum filename lengths of 14,30,62 and 126 respectively. However
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be advised that every filename whatever length occupies this space, so if you
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set the increment to 8 then a filename of length 1 will still use up the same
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space in a directory as a filename of length 126. Setting this too high will
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slow down directory operations somewhat. 2 is a reasonable value for this
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parameter. NB If you use Minix itself then only the default increment (1) is
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accessible to Minix; other values will seriously confuse Minix, so if you want
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partitions to be accessible to Minix use increment 1 (the default).
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The -n option allows you to set the directory increment, follow it by
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the increment you want. If this option is not present then a value of one is
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assumed.
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PROTECTION
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A couple of options deal with 'protection'. This is a somewhat tricky
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subject. Basically protection is a method I use to prevent TOS from writing
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to a Minixfs partition when MiNT is not running, if TOS did then the partition
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would be damaged (possibly irreparably). If you will always use MiNT and
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Minixfs, or you are absolutely certain you will never write to a Minixfs
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partition without MiNT/Minixfs running then feel free to use no protection at
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all.
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However this is rather unlikely so you usually will need some form of
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protection. There are currently two methods. Null Disk and other partition ID.
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A Null disk makes TOS think it's root directory is full so it
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can't write to a filesystem because it can't create any files.
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If Null disk doesn't work then you can try an alternate partition ID.
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This only works if you have software with an XHDI version of 1.10 or higher,
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if you use the '-t' option to minit you can find out your XHDI version (if any).
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The partition ID is a three character identifier for the partition type. TOS
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uses GEM and BGM for its filesystems; you can use other types to ensure TOS
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will never access the partition and Minixfs can. There are quite a few problems
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though. Not all hard disk software allows the partition ID to be edited. Also
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Minixfs can only automatically access other partitions with XHDI compliant
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software (see the information provided by the '-t' option).
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If you have XHDI compliant software and you can edit the partition ID
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then you can use the ID MIX for Minixfs (you can also use RAW, but I wouldn't
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advise it). After altering the ID, reboot and use minit as normal and all should
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be OK.
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OTHER OPTIONS
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Normally minit tries to find out the size of a partition by itself,
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this can sometimes fail. If it does then you must enter the partition size
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(in K) manually with the -b option.
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Inodes are part of the filesystem. Every file/directory/symbolic link
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on the filesystem uses precisely one inode. If you run out of inodes then you
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can't create any more files/directories/symbolic links without first deleting
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some already there. The default number of inodes is a third the partition size
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in K. If you want to create more then use the '-i' option followed by the number
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you want. You can have at most 65535 inodes on a filesystem. The default will
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almost always suffice, but you can increase this if you will need more.
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The -S option writes out part of the filesystem called the 'super
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block' only. If you accidentally wipe out the start of a partition then this
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option may allow some data to be salvaged. If the start of a partition is
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wiped out then the partition may not be even recognised as minix, so the -S
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option can help under these rare circumstances. Note: you must use exactly the
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same pararmeters you used to create the fileystem in the first place.
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The -t option is a test option. It does almost everything needed to
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create a filesystem without writing anything. It also gives a status report
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of any options (e.g. XHDI support) the driver software may have. Use of '-t'
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is recommended before actually creating the partition; it wont harm anything.
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HUGE PARTITIONS
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A *huge* partition is a partition where the logical sector size is
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bigger than 1K. In practice this means bigger than 64Mb (or 32Mb with some
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partitioning software). Unlike TOS filesystems when you create a Minixfs
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filesystem bigger than 64Mb the filesystem is still accessed in 1K blocks.
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In this sense if you create a 1 byte file when the logical sector size is
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e.g. 4K you use up 1K of the disk not the 8K (2 sectors) TOS filesystems
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would use.
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If the partition you are creating is huge then you may have some
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problems. This is basically down to bugs and inconsistencies in driver
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software. I've tried to work around these as much as possible, but I can't
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guarantee anything. The rules are explained below, which should help if you
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want to create such a partition and minit complains. Generally minit will
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complain if it can't find a work around for your software.
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If the drive letter is A-P (inclusive) you should always be OK. If
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you are using software which conforms to XHDI then you should also have no
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problems (and you might want to set the partition ID to MIX as well). If
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neither is the case then you may need to either obtain XHDI compatible disk
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software or repartition/reorder (set the ID's so the large partition is on
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the first hard drive) to make the large partition drive A-P.
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The A-P restriction may be fixed in future versions of Minixfs if there
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is any demand (however it is rather tricky to do).
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RECREATING A TOS PARTITION
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If you decide you want to turn a Minixfs partition back into a normal
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TOS partition then you can use the '-r' option. This will recreate a blank
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TOS filesystem on the partition selected. Certain hard disk software may not
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recognise the new filesystem, so always reboot after you use this option.
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Note: This option only works at present if you created the filesystem with
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a newer version of minit. If there is any demand I may add an option for it
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to work if the filesystem is older, by 'improvising' a bit.
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Some hard disk software (e.g. ICD) and disk tools have an option to
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rebuild a single partition without disturbing the others. If you have such
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sofware then please use as opposed to the '-r' option. Such software will
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probably work under all circumstances (e.g. filesystems made with older minit
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versions). The primary reason I added the '-r' option was to allow people
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without partition rebuilding software to be saved the effort of reformatting
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or repartitioning their hard disks to get a TOS filesystem back.
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USING MINIT
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After all the options must come a drive letter (either case) followed
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by a colon. You will then be given a warning, if you type 'y' or 'Y' then the
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process continues, otherwise it is aborted. If you are running Minixfs/MiNT
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the partition should be instantly recognisable. To check try using 'mfsconf'
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and you should get some status info about translation modes (see minixfs.doc).
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If you get the message 'drive X: is not minix' then there may be a problem.
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Try rebooting, if that doesn't work try recreating a TOS partition (there
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should be an option in you hard disk driver sofware to do this) and using
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minit without any protection options. If this still fails then your system
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hard disk driver software currently cannot use Minixfs partitions. Send me
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a report (see the file 'bugs.doc') and I'll see what I can do.
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WARNING: you should not make the partition you boot from or the partition that
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you load MiNT and minix.xfs a Minixfs partition. This is because TOS cannot boot
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a Minixfs partition or run MiNT/minix.xfs from a Minixfs partition.
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EXAMPLES
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Create a minixfs filesystem on drive A:
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minit A:
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Create a V2 filesystem on E:
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minit -V E:
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Create a V2 filesystem with increment 2 and null disk protection on drive D:
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minit -V -d 2 -P D:
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Test the disk driver software used to access drive F:
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minit -t F:
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