How to Confirm DIRECT IO is Getting Used on Solaris

Posted in: Technical Track

Hi! Recently I was working on a task wherein I had to confirm if the direct IO is in use or not.

filesystem_io_option database parameter was set to “DIRECTIO” to make use of directio.

Now in Linux it becomes very easy.you just need to read /proc/slabinfo :

cat /proc/slabinfo | grep kio

In the SLAB allocator there are three different caches involved. The kioctx and kiocb are Async I/O data structures that are defined in aio.h header file. If it shows a non zero value that means async io is enabled.

Initially I was looking for same kind of memory structures in Solaris but could not find so ( bad luck :( ) and so used basic tracing using truss.

First I logged into database and check the filesystem parameter ( Changed the name of the database and host :)  )

SQL> select name from v$database;

NAME
———
MYDB

SQL> show parameter filesystem

NAME TYPE VALUE
———————————— ———– ——————————
filesystemio_options string DIRECTIO

So the  database parameter has been to set to make use of directio. Now I just need to make sure that this directio really is in use (or not).

What I have done here is used truss and created a test table to check if undo and system datafiles are opened with directio or not.( see below the output )

/homedirs/oracle> truss -f -t open,ioctl -u ‘:directio’ sqlplus “/ as sysdba”

27818: open(“/var/ld/64/ld.config”, O_RDONLY) Err#2 ENOENT
27818: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libsqlplus.so”, O_RDONLY) = 3
27818: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libclntsh.so.10.1”, O_RDONLY) = 3
27818: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libnnz10.so”, O_RDONLY) = 3
27818: open(“/lib/64/libkstat.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libnsl.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libsocket.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libgen.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libdl.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libc.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/librt.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libaio.so.1”, O_RDONLY) = 3
27818: open(“/usr/lib/64/libsched.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libm.so.2”, O_RDONLY) = 3
27818: open(“/lib/64/libthread.so.1”, O_RDONLY) = 3
27818: open(“/lib/64/libmd.so.1”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx1boot.nlb”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx00001.nlb”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx20001.nlb”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx10001.nlb”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx40011.nlb”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx40001.nlb”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/sqlplus/mesg/sp1us.msb”, O_RDONLY) = 3
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/sqlplus/mesg/sp2us.msb”, O_RDONLY) = 4
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/sqlplus/mesg/cpyus.msb”, O_RDONLY) = 5
27818/1: open(“/usr/share/lib/zoneinfo/UTC”, O_RDONLY) = 6
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/oracore/zoneinfo/timezlrg.dat”, O_RDONLY) = 6
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/rdbms/mesg/ocius.msb”, O_RDONLY) = 6
27818/1: ioctl(1, TCGETA, 0xFFFFFD7FFFDFF410) = 0

SQL*Plus: Release 10.2.0.5.0 – Production on Wed May 11 12:15:22 2011

Copyright (c) 1982, 2010, Oracle. All Rights Reserved.

27818/1: open(“/proc/self/psinfo”, O_RDONLY) = 7
27818/1: open(“/var/run/name_service_door”, O_RDONLY) = 7
27818/1: ioctl(8, FIONBIO, 0xFFFFFD7FFFDF7F58) = 0
27819: open(“/var/ld/64/ld.config”, O_RDONLY) Err#2 ENOENT
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libskgxp10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libhasgen10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libskgxn2.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libocr10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libocrb10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libocrutl10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libjox10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libclsra10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libdbcfg10.so”, O_RDONLY) = 3
27819: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/lib/libnnz10.so”, O_RDONLY) = 3
27819: open(“/lib/64/libkstat.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libnsl.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libsocket.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libgen.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libdl.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libc.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/librt.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libaio.so.1”, O_RDONLY) = 3
27819: open(“/usr/lib/64/libsched.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libm.so.2”, O_RDONLY) = 3
27819: open(“/lib/64/libpthread.so.1”, O_RDONLY) = 3
27819: open(“/lib/64/libmd.so.1”, O_RDONLY) = 3
27819/1: open(“/dev/null”, O_RDONLY) = 3
27819/1: open(“/proc/27819/psinfo”, O_RDONLY) = 5
27819/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx1boot.nlb”, O_RDONLY) = 5
27819/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx00001.nlb”, O_RDONLY) = 5
27819/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx20001.nlb”, O_RDONLY) = 5
27819/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx10001.nlb”, O_RDONLY) = 5
27819/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx40011.nlb”, O_RDONLY) = 5
27819/1: open(“/dev/null”, O_RDONLY) = 5
27819/1: open(“/var/run/name_service_door”, O_RDONLY) = 7
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/nls/data/lx207d0.nlb”, O_RDONLY) = 9
27818/1: ioctl(0, TCGETA, 0xFFFFFD7FFFDFA9B0) = 0
27818/1: open(“/etc/ttysrch”, O_RDONLY) = 9
27818/1: ioctl(9, SIOCGIFNUM, 0xFFFFFD7FFFDFA2AC) = 0
27818/1: ioctl(9, SIOCGIFCONF, 0xFFFFFD7FFFDFA258) = 0
27818/1: ioctl(9, SIOCGIFFLAGS, 0x00521E90) = 0
27818/1: ioctl(9, SIOCGIFFLAGS, 0x00521EB0) = 0
27818/1: ioctl(9, SIOCGIFADDR, 0x00521EB0) = 0
27818/1: ioctl(9, SIOCGARP, 0xFFFFFD7FFFDFA26C) = 0
27819/1: open(“/dev/zero”, O_RDONLY) = 8
27819/1: ioctl(0, TCGETA, 0xFFFFFD7FFFDF9F20) = 0
27819/1: open(“/etc/ttysrch”, O_RDONLY) = 10
27819/1: open(“/usr/share/lib/zoneinfo/UTC”, O_RDONLY) = 10
27819/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/rdbms/mesg/oraus.msb”, O_RDONLY) = 10
27819/1: open(“/etc/netconfig”, O_RDONLY|O_LARGEFILE) = 11
27819/1: open(“/dev/udp”, O_RDONLY) = 11
27819/1: ioctl(11, SIOCGLIFNUM, 0xFFFFFD7FFFDFA890) = 0
27819/1: open(“/etc/default/nss”, O_RDONLY|O_LARGEFILE) = 11
27819/1: open(“/ora01/homedirs/oracle/admin/MYDB/adump/MYDB_ora_27819_1.aud”, O_RDWR|O_CREAT|O_EXCL, 0660) = 11
27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/rdbms/mesg/oraus.msb”, O_RDONLY) = 12

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

27818/1: open(“/ora01/homedirs/oracle/product/10.2.0/db_1/sqlplus/admin/glogin.sql”, O_RDONLY) = 12
SQL> 27818/1: ioctl(0, TCGETA, 0xFFFFFD7FFFDFAC60) = 0

SQL> create table test ( t number);
27819/1: open(“/ora02/oradata/MYDB/undotbs101.dbf”, O_RDWR|O_DSYNC) = 13
27819/1@1: -> libc:directio(0x100, 0x1, 0x0, 0x0, 0xfefefefeffffffff, 0xfefefefeff726574)
27819/1: ioctl(256, _ION(‘f’, 76, 0), 0x00000001) = 0
27819/1@1: <- libc:directio() = 0
27819/1: open(“/ora02/oradata/MYDB/system01.dbf”, O_RDWR|O_DSYNC) = 13
27819/1@1: -> libc:directio(0x101, 0x1, 0x0, 0x0, 0xfefefefeffffffff, 0xfefefefeff726574)
27819/1: ioctl(257, _ION(‘f’, 76, 0), 0x00000001) = 0
27819/1@1: <- libc:directio() = 0

Table created.

SQL> drop table test;

Table dropped.

See the line “ioctl(256, _ION(‘f’, 76, 0), 0x00000001)” above.

The 3rd parameter as shown in the above output/line to the ioctl() call decides the use of direct IO.
It is 0 for directio off, and 1 for directio on and its ON in case of this database.i.e undo and system datafiles are opened with directio.

So with this it is confirmed that filesystem_io_option parameter is in effect and the database is making use of directio.

Now lets try this on a database with async io:

QL> select name from v$database;

NAME
———
MYANOTHERDB

SQL> show parameter filesystem

NAME                                 TYPE        VALUE
———————————— ———– ——————————
filesystemio_options                 string      asynch

data/home/oracle> truss -f -t open,ioctl -u ‘:directio’ sqlplus “/ as sysdba”

13874:  open(“/var/ld/64/ld.config”, O_RDONLY)          Err#2 ENOENT
13874:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libsqlplus.so”, O_RDONLY) = 3
13874:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libclntsh.so.10.1”, O_RDONLY) = 3
13874:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libnnz10.so”, O_RDONLY) = 3
13874:  open(“/lib/64/libkstat.so.1”, O_RDONLY)         = 3
13874:  open(“/lib/64/libnsl.so.1”, O_RDONLY)           = 3
13874:  open(“/lib/64/libsocket.so.1”, O_RDONLY)        = 3
13874:  open(“/lib/64/libgen.so.1”, O_RDONLY)           = 3
13874:  open(“/lib/64/libdl.so.1”, O_RDONLY)            = 3
13874:  open(“/lib/64/libc.so.1”, O_RDONLY)             = 3
13874:  open(“/lib/64/librt.so.1”, O_RDONLY)            = 3
13874:  open(“/lib/64/libaio.so.1”, O_RDONLY)           = 3
13874:  open(“/usr/lib/64/libsched.so.1”, O_RDONLY)     = 3
13874:  open(“/lib/64/libm.so.2”, O_RDONLY)             = 3
13874:  open(“/lib/64/libthread.so.1”, O_RDONLY)        = 3
13874:  open(“/lib/64/libmd.so.1”, O_RDONLY)            = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx1boot.nlb”, O_RDONLY) = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx00001.nlb”, O_RDONLY) = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx20001.nlb”, O_RDONLY) = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx10001.nlb”, O_RDONLY) = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx40011.nlb”, O_RDONLY) = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx40001.nlb”, O_RDONLY) = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/sqlplus/mesg/sp1us.msb”, O_RDONLY) = 3
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/sqlplus/mesg/sp2us.msb”, O_RDONLY) = 4
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/sqlplus/mesg/cpyus.msb”, O_RDONLY) = 5
13874/1:        open(“/usr/share/lib/zoneinfo/UTC”, O_RDONLY)   = 6
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/oracore/zoneinfo/timezlrg.dat”, O_RDONLY) = 6
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/rdbms/mesg/ocius.msb”, O_RDONLY) = 6
13874/1:        ioctl(1, TCGETA, 0xFFFFFD7FFFDFF460)            = 0

SQL*Plus: Release 10.2.0.5.0 – Production on Wed May 11 12:15:05 2011

Copyright (c) 1982, 2010, Oracle.  All Rights Reserved.

13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/network/admin/sqlnet.ora”, O_RDONLY) = 7
13874/1:        ioctl(7, TCGETA, 0xFFFFFD7FFFDF7DF0)            Err#25 ENOTTY
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/network/admin/sqlnet.ora”, O_RDONLY) = 7
13874/1:        ioctl(7, TCGETA, 0xFFFFFD7FFFDF7E50)            Err#25 ENOTTY
13874/1:        open(“/proc/self/psinfo”, O_RDONLY)             = 7
13874/1:        open(“/var/run/name_service_door”, O_RDONLY)    = 7
13874/1:        ioctl(8, FIONBIO, 0xFFFFFD7FFFDF7FA8)           = 0
13875:  open(“/var/ld/64/ld.config”, O_RDONLY)          Err#2 ENOENT
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libskgxp10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libhasgen10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libskgxn2.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libocr10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libocrb10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libocrutl10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libjox10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libclsra10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libdbcfg10.so”, O_RDONLY) = 3
13875:  open(“/global/opt/oracle/product/10.2.0/db_2/lib/libnnz10.so”, O_RDONLY) = 3
13875:  open(“/lib/64/libkstat.so.1”, O_RDONLY)         = 3
13875:  open(“/lib/64/libnsl.so.1”, O_RDONLY)           = 3
13875:  open(“/lib/64/libsocket.so.1”, O_RDONLY)        = 3
13875:  open(“/lib/64/libgen.so.1”, O_RDONLY)           = 3
13875:  open(“/lib/64/libdl.so.1”, O_RDONLY)            = 3
13875:  open(“/lib/64/libc.so.1”, O_RDONLY)             = 3
13875:  open(“/lib/64/librt.so.1”, O_RDONLY)            = 3
13875:  open(“/lib/64/libaio.so.1”, O_RDONLY)           = 3
13875:  open(“/usr/lib/64/libsched.so.1”, O_RDONLY)     = 3
13875:  open(“/lib/64/libm.so.2”, O_RDONLY)             = 3
13875:  open(“/lib/64/libpthread.so.1”, O_RDONLY)       = 3
13875:  open(“/lib/64/libmd.so.1”, O_RDONLY)            = 3
13875/1:        open(“/dev/null”, O_RDONLY)                     = 3
13875/1:        open(“/proc/13875/psinfo”, O_RDONLY)            = 5
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx1boot.nlb”, O_RDONLY) = 5
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx00001.nlb”, O_RDONLY) = 5
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx20001.nlb”, O_RDONLY) = 5
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx10001.nlb”, O_RDONLY) = 5
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx40011.nlb”, O_RDONLY) = 5
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/network/admin/sqlnet.ora”, O_RDONLY) = 5
13875/1:        ioctl(5, TCGETA, 0xFFFFFD7FFFDFE100)            Err#25 ENOTTY
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/network/admin/sqlnet.ora”, O_RDONLY) = 5
13875/1:        ioctl(5, TCGETA, 0xFFFFFD7FFFDFE160)            Err#25 ENOTTY
13875/1:        open(“/dev/null”, O_RDONLY)                     = 5
13875/1:        open(“/var/run/name_service_door”, O_RDONLY)    = 7
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx2001f.nlb”, O_RDONLY) = 9
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/nls/data/lx207d0.nlb”, O_RDONLY) = 9
13874/1:        ioctl(0, TCGETA, 0xFFFFFD7FFFDFAA00)            = 0
13874/1:        open(“/etc/ttysrch”, O_RDONLY)                  = 9
13874/1:        ioctl(9, SIOCGIFNUM, 0xFFFFFD7FFFDFA2FC)        = 0
13874/1:        ioctl(9, SIOCGIFCONF, 0xFFFFFD7FFFDFA2A8)       = 0
13874/1:        ioctl(9, SIOCGIFFLAGS, 0x00411840)              = 0
13874/1:        ioctl(9, SIOCGIFFLAGS, 0x00411860)              = 0
13874/1:        ioctl(9, SIOCGIFADDR, 0x00411860)               = 0
13874/1:        ioctl(9, SIOCGARP, 0xFFFFFD7FFFDFA2BC)          = 0
13875/1:        open(“/dev/zero”, O_RDONLY)                     = 8
13875/1:        ioctl(0, TCGETA, 0xFFFFFD7FFFDF9F60)            = 0
13875/1:        open(“/etc/ttysrch”, O_RDONLY)                  = 10
13875/1:        open(“/usr/share/lib/zoneinfo/UTC”, O_RDONLY)   = 10
13875/1:        open(“/global/opt/oracle/product/10.2.0/db_2/rdbms/mesg/oraus.msb”, O_RDONLY) = 10
13875/1:        open(“/etc/netconfig”, O_RDONLY|O_LARGEFILE)    = 11
13875/1:        open(“/dev/udp”, O_RDONLY)                      = 11
13875/1:        ioctl(11, SIOCGLIFNUM, 0xFFFFFD7FFFDFA8D0)      = 0
13875/1:        open(“/etc/default/nss”, O_RDONLY|O_LARGEFILE)  = 11
13875/1:        open(“/global/opt/oracle/admin/MYANOTHERDB/adump/MYANOTHERDB_ora_13875_1.aud”, O_RDWR|O_CREAT|O_EXCL, 0660) Err#17 EEXIST
13875/1:        open(“/global/opt/oracle/admin/MYANOTHERDB/adump/MYANOTHERDB_ora_13875_2.aud”, O_RDWR|O_CREAT|O_EXCL, 0660) = 11
13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/rdbms/mesg/oraus.msb”, O_RDONLY) = 12

Connected to:
Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

13874/1:        open(“/global/opt/oracle/product/10.2.0/db_2/sqlplus/admin/glogin.sql”, O_RDONLY) = 12
SQL> 13874/1:   ioctl(0, TCGETA, 0xFFFFFD7FFFDFACB0)            = 0

SQL> create table test( t number);
13875/1:        open(“/global/db/data01/MYANOTHERDB/undotbs01.dbf”, O_RDWR|O_DSYNC) = 13
13875/1@1:      -> libc:directio(0x100, 0x0, 0x0, 0x0, 0xfefefefeffffffff, 0xfefefefeff726574)
13875/1:        ioctl(256, _ION(‘f’, 76, 0), 0x00000000)        = 0
13875/1@1:      <- libc:directio() = 0
13875/1:        open(“/global/db/data01/MYANOTHERDB/system01.dbf”, O_RDWR|O_DSYNC) = 13
13875/1@1:      -> libc:directio(0x101, 0x0, 0x0, 0x0, 0xfefefefeffffffff, 0xfefefefeff726574)
13875/1:        ioctl(257, _ION(‘f’, 76, 0), 0x00000000)        = 0
13875/1@1:      <- libc:directio() = 0



Table created.

SQL> drop table test;

Table dropped.

SQL> exit
Disconnected from Oracle Database 10g Enterprise Edition Release 10.2.0.5.0 – 64bit Production
With the Partitioning, OLAP, Data Mining and Real Application Testing options

In above output, ioctl(257, _ION(‘f’, 76, 0), 0x00000000)  , 3rd parameter to ioctl call  is 0 i.e. direct IO is not in use.

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2 Comments. Leave new

Francois Marcoux
June 14, 2011 8:32 am

You may also use DTrace. See for instance http://blogs.oracle.com/apatoki/entry/ensuring_that_directio_is_active (I have not tested those scripts since 2009).

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Alex Gorbachev
June 24, 2011 5:08 pm

Kyle Hailey commented via Facebook here – http://www.facebook.com/notes/the-pythian-group/how-to-confirm-direct-io-is-getting-used-on-solaris/10150207590160841

good timing – I just looking on Google for this yesterday! Wish there was an easier way. Also another good question is why DIO is not used when it is set in the database. ZFS doesn’t support DIO. I believe for Veritas, vxfs, DIO is not available by default and requires some extra steps. What’s the easiest way to see the filesystems? Not sure but I was looking at /etc/vfstab

nice examples here: http://yong321.freeshell.org/oranotes/DirectIO.txt

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