Is 15 second for log archiving acceptable ?

Question

Version : 11.2.0.3
Platform : RHEL 5.4
3-Node RAC
DB in ARCHIVELOG mode
Question1
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As you can see below sometimes it takes upto 15 seconds for the archiving of Redo logs.
Online redo log switching is happening fast though . It takes less than 2 seconds (maybe not fast enough for you guys )
Is this acceptable ?
--- Log archiving is slow
SQL> set timing on
SQL> alter system archive log current;
System altered.
Elapsed: 00:00:11.08
SQL>
SQL>
SQL> alter system archive log current;
System altered.
Elapsed: 00:00:10.77
SQL> alter system archive log current;
System altered.
Elapsed: 00:00:15.06
SQL>
SQL>
-- But log switching is fast !
SQL> alter system switch logfile;
System altered.
Elapsed: 00:00:01.89
SQL> alter system switch logfile;
System altered.
Elapsed: 00:00:00.21Question2.
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For a DB in archivelog mode, ALTER SYSTEM ARCHIVE LOG CURRENT and ALTER SYSTEM SWITCH LOGFILE have the same effect . Right ? I mean, both of these commands asks the archiver process to archive the ORL which is being currently written to. Right ?

Answer 1

It's fast enough as long as you don't fill up all the online redo before you are finished archiving the first one. It's a round-robin, so if you get all the way around to the first one which is still being archived, everything will stop until it is done.
The ALTER SYSTEM ARCHIVE LOG CURRENT waits for the archiver to finish archiving, so it is slower than ALTER SYSTEM SWITCH LOGFILE, possibly much much so with larger redo.