Oracle-L: Re: db_files and file descriptors on solaris7

From: Shaleen <shgarg_orafaq_at_hotmail.com>
Date: Tue, 31 Dec 2002 11:49:47 -0800
Message-ID: <F001.00524E90.20021231114947@fatcity.com>

Found following on metalink but this does not explain why we never saw the message when we were running on 64 descriptors and 200 files

file descriptor limit. Tune your system to increase this limit to avoid severe performance'

The OS file-opening limit should not be greater than number of files Oracle opens. That is determined by the following

db_files*2 ( twice for equal number of temp files to be opened) + 2* maximum_no_of_log_files_simultaneously_opened + maximum_number_of_controlfiles + safety_margin_for_misc_files (like trace . etc. minimum 32 )

If this is greater than OS Limit , message is flagged and file descriptors are recycled. In your case the calculated limit would be 4000*2 + 2*8 (assuming) + 8(assuming) + 32 = 8056 Since 8056 > 4096 the message is shown. Try a value for db_files, which is little below than ½ the OS limit . Thank you
Giridhar

Original Message ----- From: Shaleen To: Multiple recipients of list ORACLE-L Sent: Tuesday, December 31, 2002 11:40 AM Subject: db_files and file descriptors on solaris7

All,

Yesterday we increased db_files from 200 to 500 and recieved following message in alert log.

Oracle instance running on a system with low open file descriptor limit. Tune your system to increase this limit to avoid severe performance degradation.

Our file descriptors is set to 1024. Reducing db_files to 400 did not give this message. Interesting thing is that we increased file descriptors very recently from 64 to 1024. Does anyone have more information on this?

Thanks
Shaleen

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Author: Shaleen
INET: shgarg_orafaq_at_hotmail.com

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