ARCHIVE LOG --- All transactions either rolled back or
committed/externalized to table.
ACTIVE LOG --- At least one transaction either in flight or
committed/not-externalized.
NEXT ACTIVE LOG --- File id of next log to be used and currently empty.
Say:
S0000001.log and S0000002.log are ARCHIVE, S0000003.log is FULL and ACTIVE
and S0000004.log is NOT FULL and ACTIVE and Current; and S0000005.log is
NEXT ACTIVE.
If S000004 fills up and S0000003 is still ACTIVE then logging will happen in
S0000005. If the situation does not change and S0000005 fills then S0000006
will get allocated and so on.
If you are in LOG RETAIN=RECOVERY and USEREXIT=ON then DB2 will have
archived logs 1,2,3. In that case, DB2 will rename log 1 to log 5 instead
of allocating a new one and reuse its space. It will do the same for log 2.
You would now have log 3 and 4 and 5 (Old No. 1)ACTIVE and 6 (Old No.2) NEXT
ACTIVE.
If DB2 cannot rename and reuse, then it will allocate new files on demand.
Your limit therefore for the log space in total becomes the file systems
capacity.
Now, if LOGSECOND is NOT set to -1 but to a positive integer, then the limit
is: from the the first acitve (Log3), the space used cannot be more than the
total number of files=Lofprimary+logsecond. Assume they are set to 10 and
15 respectively. Then if if Log3 is active and you have a very long running
transaction and 3 stays active, you would get a log full condition when DB2
attempts to open S0000028. The db will go automatically in crash restart
mode.
If LOGSECOND=-1, then DB2 will keep opening logs on demand until it runs out
of file system space (This V8 only).
HTH, Pierre.
"hank" <gang36@hotmail.com> a écrit dans le message de
news:8d54c48d.0402041012.19801ad2@posting.google.c om...[color=blue]
> "Fan Ruo Xin" <fanruox@sbcglobal.net> wrote in message[/color]
news:<ajZTb.3$PY.1@newssvr26.news.prodigy.com>...[color=blue][color=green]
> > "hank" <gang36@hotmail.com> wrote in message
> > news:8d54c48d.0402030919.640c76e9@posting.google.c om...[color=darkred]
> > > "Fan Ruo Xin" <fanruox@sbcglobal.net> wrote in message[/color]
> > news:<%4FTb.274$Gr6.89@newssvr26.news.prodigy.com>...[color=darkred]
> > > > "hank" <gang36@hotmail.com> wrote in message
> > > > news:8d54c48d.0402021058.6985d36a@posting.google.c om...
> > > > > Hi All
> > > > >
> > > > > In the Circular Logging when the Primary Log file fill up, the
> > > > > database manager will creat a secondary log files for the[/color][/color][/color]
transaction;[color=blue][color=green][color=darkred]
> > > > > when this transaction finished, the secondary log files still
> > > > > allocated in log directory; when all application disconnect from
> > > > > database or database reactive or database restart the secondary[/color][/color][/color]
log[color=blue][color=green][color=darkred]
> > > > > files will be deleted from log directory. For each transaction log
> > > > > request, database manager always first look primary log, if it is[/color][/color][/color]
no[color=blue][color=green][color=darkred]
> > > > > reuseable in primary log, then move to secondary log.
> > > > >
> > > > > My question is
> > > > > how database manager use the already allocated secondary log file?[/color]
> > Just like db2 server use the primary log files[color=darkred]
> > > > > if one transaction log is using 10% of one secondary log file, and
> > > > > same time will another transaction log use the rest of 90% of same
> > > > > secondary log file?
> > > > Either the log file is primary or secondary, they should be used by[/color][/color][/color]
the[color=blue][color=green]
> > all[color=darkred]
> > > > the transactions/agents. Let's say you have three primary log files[/color]
> > log01,[color=darkred]
> > > > log02, log03. If db2 server find out when the log03 is full, but the[/color]
> > log01[color=darkred]
> > > > still hold the active transactions, then db2 will allocate the[/color][/color][/color]
secondary[color=blue][color=green][color=darkred]
> > > > files and switch the current log file to the first secondary log[/color][/color][/color]
file.[color=blue][color=green][color=darkred]
> > >
> > > So, does it mean in the high cocurrent and long running transaction
> > > processes, the database manage only can handle 126 tansaction in DB2
> > > UDB v7.2 and 256 in DB2 UDB v8.1?[/color]
> > =========
> > No. First, the active log file doesn't mean it is current log file.[/color][/color]
There[color=blue][color=green]
> > may be a couple of active log files, when all the primary + secondary[/color][/color]
files[color=blue][color=green]
> > is used, then you will get "log full". But there is only one current log
> > file (it might be primary log file, or seconday log file). All the[/color][/color]
active[color=blue][color=green]
> > transactions will write to the current log file. And db2 server will[/color][/color]
know[color=blue][color=green]
> > which transaction corresponse which session.
> > How many concurrent transactions can db2 server handle? This is not
> > determined by the number of log files. This will be determined by the[/color][/color]
number[color=blue][color=green]
> > of concurrent db2 agents, which will be the min(max_agents,
> > max_applications), of course there is also os limits ....
> > =========[/color]
> Thank you for you response, but one log file become reuseable when it
> is not a current log file and not a active log file, if all log file
> is used now but not all fill up, which log file is reuseable? if not,
> where to allocate the log space for this transaction?
>[color=green][color=darkred]
> > >
> > > > > if one transaction log need to move to secondary log, does it use
> > > > > existed one or to allocate new one?[/color]
> > the existed one.[color=darkred]
> > > > >
> > > > > Any help will be very useful
> > > > >
> > > > >
> > > > > Hank[/color][/color][/color]
