tru64 cluster file system是direct IO嗎

[watermelonyu]

請問在tru64 cluster 的cluster file system 是

direct IO嗎

node1: tru51a

node2: tru51b

因為我在tru51b mount 起來的時候,我在tru51a就可以看到該mount point,在tru51a 並不需要做再mount的動作

這時候假如我在tru51a 對u01 做寫入的動作,到底是直接寫入u01還是透過tru51b做寫入

example

Domain or filesystem name = u01 u01

Mounted On u01

Server Name = tru51b

Server Status : OK

[watermelonyu]

not direct i/o, the i/o request will from your tru51a though tru51b to /u01. if the i/o request is large amount, this will lower your tru51b system performance.



suggest you can split the i/o by use the customise script add in "/etc/inet.local" each node, when system boot up, your script need to check if the filesystem mount at correct host.

[watermelonyu]

我在一篇文章上看到(requires O_DIRECTIO)就可以做到direct io,請問O_DIRECTIO是怎樣做到的



write (an AdvFS file was opened with the O_DIRECTIO flag) or when an

application performs asynchronous Direct I/Os to files using the aio_raw library,

[watermelonyu]

全文如下

Tru64 CFS is a layer on top of the Advfs file system. When direct I/O is enabled for a file by opening the file with the o_directio flag, read and write requests on it are executed to and from disk storage through direct memory access, bypassing AdvFS and CFS caching. This improves I/O performance for database applications that do their own caching and file region synchronization.

[watermelonyu]

Oracle uses the direct I/O feature available in CFS. Direct I/O enables Oracle to bypass the buffer cache (no caching at file system level). Oracle manages the concurrent access to the file itself as it does on raw devices. Direct I/O does not go through the CFS server. File creation and resizing is seen as a metadata operation by Advfs and this has to be done by the CFS server. Consequently, file creations and resizes must be run on the node where the CFS server is located. File operations might take longer when the CFS server is remote.

這樣看起來oracle 可以使用到directio 的功能,那一般在非資料庫對於file 的存取有辦法做到directio嗎

[watermelonyu]

Hi Joey,



> 請問在tru64 cluster 的cluster file system 是 direct IO嗎

> node1: tru51a

> node2: tru51b



The CFS is default supported the DirectIO without

defined "O_DIRECTIO" on TCR V5.1B.



PS: Please don't join the different TCR OS version into a same cluster. Hope both tru51a and tru51b just is a hostname.



Best regards,

Richard.

[watermelonyu]

Hi Joey,



In Oracle vendor:

1) 8.1.7.x last official standard supported 8i release Supports AdvFS and CFS DirectIO

2) ORACLE 9i: 9.0.1/9.0.2 only supported on V5.x Support AdvFS/CFS DirectIO



Feature enabled DirectIO just as on single system Application must specify O_DIRECTIO flag on open().

But Oracle 8.1.7 (or above) automatically opens all AdvFS files within the database with the O_DIRECTIO

flag if the RDBMS is running on Tru64 UNIX V5.0A and above.



On Tru64/TruCluster V5.1

Support for CFS Concurrent Direct I/O

Supported for files open with O_DIRECTIO in AP.

Non-allocation read/write operations can go directly to storage

..

..



On Tru64/TCR V5.1A

CFS Direct I/O for regular file access

CCR - code name for Cached Direct Access Reads

CFS clients now read AdvFS files directly from storage - no interconnect traffic

..

CFS still does readaheads

Optimization does not require O_DIRECTIO directive

Cached direct access reads



Because some metadata operations (file size changes) must go to CFS server via function shipping

In an ORACLE environment this would operations such as Table Space resize, extends and creates

Changes of existing database blocks will use CFS Direct I/O Targeted for data base applications

===> So please using cfsmgr to re-allocate its own file systems at the correct cluster member before

Oracle DB running. Otherwise, you will be encountered some performance impact.



PS: Both "drdmgr" and "cfsstat directio" displays statistics on reads, writes, hole writes,

extending writes, aios, etc for reference.



About the DirectIO development in TCR cluster, please see the attachment!



Best regards,

Richard.

[watermelonyu]

yes,tru51a tru51b just a hostname

os version is 5.1B