RE: High "log file sync" Waits in Statspack, - Online Redo Logs on Mounted File system of SAN Storage

  • From: VIVEK_SHARMA <VIVEK_SHARMA@xxxxxxxxxxx>
  • To: "oracle-l@xxxxxxxxxxxxx" <oracle-l@xxxxxxxxxxxxx>
  • Date: Sat, 12 Jan 2008 07:47:33 +0530

Folks

During a Benchmark Run of OLTP Transactions very High "log file sync" wait is 
occuring
Storage Box - Sun StoreEdge 9990V (Hitachi SAN)
Online Redo logfiles exist on Mounted Filesystem on a LUN / Volume of 4+4 Hard 
Disks , (RAID 1+0 Type)
Hard Disk - 15 K RPM
Storage Cache - 128 GB
Online Redo Logfile size 750 MB
log_buffer= 4M

Oracle 10.2.0.3
Solaris 10

Qs On the Storage Box, should a few of its HBA Controllers & respective Ports 
be assigned dedicatedly only to the online Redo LUN / Volume?
Qs Should Online Redo Logiles be moved to RAW Devices on the SAN Storage?
Qs Any advisable init.ora parameters?

Qs How should this issue be approached?

Will share Statspack as needed

Cheers & Thanks

P.S.

Top 5 Timed Events                                                 Avg    %Total

~~~~~~~~~~~~~~~~~~                                                 wait   Call

Event                                     Waits        Time (s)    (ms)   Time

----------------------------------------- ------------ ----------- ------ ------

log file sync                             3,511,274    328,288     93     73.6

SQL*Net break/reset to client             732,491      49,120      67     11.0

CPU time 31,699 7.1

latch: virtual circuit queues             1,099,453    10,695      10     2.4

db file parallel write                    3,253,478    9,535       3      2.1

-------------------------------------------------------------



Host CPU (CPUs: 80)

~~~~~~~~ Load Average

Begin    End      User    System   Idle   WIO     WCPU

------- -------   ------- ------- ------- ------- --------

                9.13    1.79

               16.35   23.30   60.35    0.00    2.79



Load Profile     Per Second Per  Transaction

~~~~~~~~~~~~     --------------- ---------------

Redo size:       3,143,457.88    4,121.10

...

Block changes:   15,320.88       20.09

...

Physical writes: 2,176.56        2.85

...

Executes:        12,950.32       16.98

Transactions:    762.77

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