Re: What is the size of arc files

U C wrote:

> Hi All,
> I would like to know few things from about different log files:
>
> 1) What is the size of arc file. When it creates new files and what is
> the maximum size that it can have.

Assuming you mean an archived log file, it's simply a copy of a log file set aside by the archiver process to be available for database recovery if needed. When the database is running with archiving enabled and active, each log switch should not be considered complete until the log file is archived.

Depending on your needs (and assuming you are using archiving), you might decide to keep all the archived log files online or near line.

If archiving is not used, there are no archive files. Otherwise each is the size of the log file it archives, and you have as many online and nearline as are needed for your recovery strategy.

One way to look at log sizes: the size of the log file is the unit of unrecoverable transactions - if your log file is sized for a switch at 10 minutes, the worst case scenario is that you will lose 10 minutes of transactions (assuming all log files die or become corrupt & you are actively archiving). Or you could tell you entry clerks they need to keep 2 hours worth of paper on their desk because you size the log files for a switch every 2 hours. (The time is your decision, the size is determined by benchmarking or observation.)

>
> 2) What is the size of trc files. When it creates new files and what
> is the maximum size that it can have.

Depends on the size you allow. Tracing has many uses and you might decide to allow the trace files to give all the relevant info, or you might decide to restrict the size using MAX_DUMP_FILE_SIZE.

You need to understand the purposes and various kinds of tracing to make that decision though. Many DBAs don't allow trace files. These same DBAs also tend not to understand tuning.

>
> 3) What is the size of core folder and how many files can be in each
> core folder and of what size.

Hopefully zero for both size and count. If you have a core dump, it generally means you are having a difficulty either with the database or with an aplication. A core dump may be the only way to determine the cause of a problem, but it needs to be turned over to a knowledgeable developer. The Core Dump Dest directory is generally only meaningful in unix, as the windows core dumps generally scribble wherever the executable happens to be.

>
> 4) If i am having nearly 250000 transaction a day then what will be
> size of my arch, core and trc.
>

7KB - if archiving is turned off, crashes and core dumps never happen, and only minimal tracing is allowed with MAX_DUMP_FILE_SIZE is set to 7KB (totally useless) ... or maybe 70GB. It depends on your business needs.

While we are at it - 250000 tx/day could result in 10MB/day worth of logs (40 bytes per tx) or 100GB/day. You need to study your transactions in slightly more depth. (Consider benchmarking.)

YOU need to make some decisions about backup/recovery strategies, tuning strategies, interaction between DBAs and Developers and so on. Once you have made those decisions, these questions will be easier to answer. Cnsider loking through the Concepts guide for ideas on these questions.

A question missing here is size of the alert.log (and the other logs) and how/when ot monitor.

/Hans Received on Tue Oct 05 2004 - 00:31:38 CDT