AceDB database.wrm syntax
on the line in interpreted according to the keyword.
Current Keywords:
- PART
- NAME
- SESSION_KEEP_ALIVE
- READLOCK_TIMEOUT
- NOLOCK
- SYNC_WRITE
note :
- lines beginning by // are comments
- a line don't exeed 512 characters.
- PART = partition
Example:
//Keyword : type hostname partition_name file_name max_size offset
PART : 1 local ACEDB block1.wrm 5000 0
PART : 1 local ACEDB block2.wrm 20000 0
- partition types :
- UNIX_FILE_SYSTEM = 1
- RAW_FILE_SYSTEM = 2
- hostname
- partition_name
- full path or "ACEDB" if relative to ACEDB variable.
- file_name
- only for unix file system : name of the partition file.
for other types, "NONE"
-
NAME
- is database name, this is set in the database super block when the database
is rebuilt. It can only be changed by rebuilding the database and can be used
as a reliable identifier for the database. This name is used in the main window
header and in status output.
-
TITLE
- is an additional database name that is reread each time the database is
restarted. It can be used to give a more temporary title to a database to give
more information about the database. This title is used in the main window
and will override the main window title in wspec/displays.wrm, its also used in
the status output.
-
SESSION_KEEP_ALIVE
- is the number of sessions to keep alive after
saving an update to the database. This number must be at least 1,
the code uses the default 2, if this value isn't set. 3 or 4 are also sensible.
If this number is much bigger than that, the amount of diskspace taken
up by data of old sessions that are kept alive, may be a considerable penalty.
-
READLOCK_TIMEOUT
- is the time in hours after which a readlock is regarded
as a left-over from a crash process. Any readlock older than that will
be removed and ignored by the current and all subsequent acedb programs.
For newer version (>= 4.8) which clean up readlocks even after unforseen
crashes this number may be quite small (even as low as 2 or 3), because
readlocks of genuinely running processes are continuously restored.
A recommended safe number is 8 to 12 depending on usage of the database.
-
NOLOCK
- On some platforms the Unix style lockf() system call is either
not supportd or is bugged. In this case you may want to
uncomment the NOLOCK line to prevent it being used.
Note that this disables one of the multiple access
checks. It therefore makes corruption of the database
by simultaneous access over the network more possible.
This is particularly a problem with an nfs mounted
database, because NFS buffering can bypass the other
acedb protections.
-
SYNC_WRITE
- If acedb databases are accessed via NFS, writes to the
database can time out and fail _WITHOUT_ acedb being able to
detect this. This can lead to corruption of the database.
Uncommenting the below line will force acedb to open
database files for writing in synchronous mode. This will
slow down the writes by a factor of at least 5, _but_ acedb
will be able to detect when writes via NFS fail. You may need
to do this if your network becomes very overloaded but you
still need to be able to update the database reliably.