Wednesday, July 30, 2008

DB block size VS File system block size

2:00 AM  Niramit Soonthawong  No comments

In oracle tuning there is one turning concept were discussed about, the topic was about oracle DB Clock Size, how much should it be.
As I read through I came up with the conclusion that

DB block size = File system block size

and the db block size should be 8K on windows.

How do you find what file system block size you system is using on windows.
On dos prompt enter
1. chkdsk partition (ie. c:, d:)
the result may be something similar to this

20482874 KB total disk space.
8898184 KB in 12301 files.
5652 KB in 461 indexes.
0 KB in bad sectors.
116126 KB in use by the system.
65536 KB occupied by the log file.
11462912 KB available on disk.

4096 bytes in each allocation unit.
5120718 total allocation units on disk.
2865728 allocation units available on disk.

the 4096 bytes in each allocation unit, third last row is the one telling what file system block size is.

or you could use

2. fsutil fsinfo ntfsinfo partition (ie. c:, d:)
the result may be something similar to

NTFS Volume Serial Number : 0x8aec1303ec12e8e9
Version : 3.1
Number Sectors : 0x0000000002afd736
Total Clusters : 0x000000000055fae6
Free Clusters : 0x000000000013f71b
Total Reserved : 0x0000000000000040
Bytes Per Sector : 512
Bytes Per Cluster : 4096
Bytes Per FileRecord Segment : 1024
Clusters Per FileRecord Segment : 0
Mft Valid Data Length : 0x00000000102cc000
Mft Start Lcn : 0x00000000000c0000
Mft2 Start Lcn : 0x00000000002afd73
Mft Zone Start : 0x0000000000253980
Mft Zone End : 0x0000000000253a00


Bytes Per Cluster is the one telling what file system block size your system is using.

To find out what db_block_size your oracle uses use the following command.
log in as sysdba and enter

show parameter db_block_size.



Resource:

Posted in: ,

0 comments:

Post a Comment