Additional explanation, why you may need to change that value.
Problem:
Alert log shows:
ORA-27090: Unable to reserve kernel resources for asynchronous disk I/O
Linux-x86_64 Error: 2: No such file or directory
Additional information: 3
Additional information: 128
Additional information: 139817340277512
Reason:
The problem is caused by a lower than recommended value for aio-max-nr. The current value is 1048576, but recommended is 3145728.
Connecting via ssh to the newly created host causes error:
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
@ WARNING: REMOTE HOST IDENTIFICATION HAS CHANGED! @
@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@@
IT IS POSSIBLE THAT SOMEONE IS DOING SOMETHING NASTY!
Someone could be eavesdropping on you right now (man-in-the-middle attack)!
It is also possible that a host key has just been changed.
The fingerprint for the ECDSA key sent by the remote host is
SHA256:AxfpHOVc8NP2OYPGce92HMa5LADDQj2V98ZKgoQHFGU.
Please contact your system administrator.
Add correct host key in /Users/mari/.ssh/known_hosts to get rid of this message.
Offending ECDSA key in /Users/mari/.ssh/known_hosts:315
ECDSA host key for 52.1.130.91 has changed and you have requested strict checking.
Host key verification failed.
Reason:
I had another server with the same Public IP, so when I connected to the old saver the host identification has been saved in known_hosts. After a while I have removed old server and created a new one and assigned the PIP. The host identification has changed, but old entries were still saved in known_hosts.
Solution:
Open /Users/mari/.ssh/known_hosts and delete only the line containing mentioned IP (52.1.130.91 in my case), save file and retry the connection. It should work now.
Databases were crashed and alert logs were showing errors:
Fri Nov 12 13:23:39 2021 Process startup failed, error stack: Errors in file /app/oracle/diag/rdbms/orcl/orcl/trace/orcl_psp0_25852.trc: ORA-27300: OS system dependent operation:fork failed with status: 11 ORA-27301: OS failure message: Resource temporarily unavailable ORA-27302: failure occurred at: skgpspawn5
We’ve implemented a procedure to take process list (by ps -ef), so output during that time was the following:
A large amount of Zombie processes, causing applications to fail.
Solution:
You may find a lot of recommendations about increasing kernel.pid_max, similarly ORA-27300: OS System Dependent Operation:fork Failed With Status: 11 (Doc ID 1546393.1). Of course, you can make this parameter unlimited, but this will not solve the problem, it will just postpone it.
If the number of files you are working on is big, then you need automation as soon as possible. This post describes find -o option, which helps you work on differently named files when their number is big.
For example, if you want to output the content of files physical_block_size and logical_block_size located under /sys/block/*/queue, run the following:
# find /sys/block/*/queue -name physical_block_size -o -name logical_block_size | while read f ; do echo "$f $(cat $f)" ; done
..
/sys/block/dm-0/queue/physical_block_size 4096
/sys/block/dm-0/queue/logical_block_size 512
/sys/block/dm-1/queue/physical_block_size 512
...
I’ve recently heard about this tool , as it is said we are learning things until the death (:
Our company is saving sar output in a text file periodicly and after performance or other issues we need to analyze it’s output to find out which resource was busy and when.. analyzing text file is time-consuming and can also cause eye tension.
I want to send email notification to my Gmail account from Linux server using Postfix client. Mails are not received and /var/log/maillog is full of the following error messages:
Aug 18 17:24:29 rac1 postfix/smtp[17580]: connect to gmail-smtp-in.l.google.com[74.125.69.27]:25: Connection timed out
Aug 18 17:24:29 rac1 postfix/smtp[17580]: connect to gmail-smtp-in.l.google.com[2607:f8b0:4001:c0d::1a]:25: Network is unreachable
Aug 18 17:24:59 rac1 postfix/smtp[17580]: connect to alt1.gmail-smtp-in.l.google.com[173.194.77.27]:25: Connection timed out
Aug 18 17:25:29 rac1 postfix/smtp[17580]: connect to alt2.gmail-smtp-in.l.google.com[173.194.219.27]:25: Connection timed out
Solution:
Configure Postfix and Gmail account accordingly.
1. Confirm that the myhostname parameter is configured with your server’s FQDN:
[root@rac1 ~]# flashgrid-node test-alerts
FlashGrid 21.2.24.58935 #bb6005e9d66650d1996184c38d2fb8a2a78420a8
License: Active, Marketplace
Licensee: Flashgrid Inc.
Support plan: 24x7
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
Test alerts were sent