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I have the following into a crontab and have 7 of these...at range of 15 minutes between one and the other:
50 8 * * * wget -q -O - http://domain.com/path/to/script.php?xxx=3
this script calls mysql, selects every record from a table, does something and updates a certain value...
while usually this script requires about +5minutes to end...and 2 or 3 disappear from running processes...other 3 or 4 do not...it seems they overlap
7020 root 0.0 % wget -q -O - http://domain.com/path/to/script.php?xxx=3
now, can be a priority problem? how to set a priority into crontab (with nice?) ? how priority manages the execution time? with highest priority the process exits before?
if i do mysql > SHOW FULL PROCESSLIST\G
they seem are yet running after 3 hours !
and also...during these sql processes the tables are readable and if not, how to avoid? the pages are served more slowly as usual
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I was currently controlling this through an uptime.
The computer restarts if uptime is greater than 1h.
But I do not know how to control if the computer is one day on or more, because currently I only control the hours.
Is it possible to control days, hours and minutes with uptime?
I need to restart the computer when the power on time is greater than 1h.
If the time is 1 day and 0 hours gives failure.
Sorry for my explanation, it is a script that does a series of things and alfinal exists this function that is responsible for controlling this parameter.
thanks for reading me
Not sure I quite understand your issue.
If you want your computer to ALWAYS reboot after a specific amount of time, which is very unusual, then use cron. Add this to /etc/crontab (alternatively, if there is a /etc/cron.d directory on your machine, you can also create a file /etc/cron.d/reboot with this content) :
#reboot root sleep 1800; /sbin/reboot
(adapt reboot's path to match your system; 1800 is the number of seconds for 30 minutes, change it to whatever delay you need)
On the other hand, you may be writing a script that will reboot your server, and you may want to keep it from working if it is run before 30 minutes of uptime (which makes more sense).
Then, I understand you have difficulties parsing the result of uptime and you should use /proc/uptime which gives your uptime in seconds:
#!/bin/sh
not_before=1800 # Number of seconds - adapt to your needs
uptime=$(cut -d . -f 1 /proc/uptime)
[ "$uptime" -ge "$not_before" ] && exec reboot
echo "Sorry, only $uptime s of uptime; you must wait $((not_before - uptime)) seconds" >&2
exit 1
If you want to do it in a script, use the result of uptime | grep " day"to determine whether to execute things (in anifcondition), then do anything you want inside theif`.
Make that script executable and put it in crontab to run every 5min or so.
More information on Cron: https://wiki.archlinux.org/index.php/Cron
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I installed openstack via devstack on Ubuntu 14.04. I have got 8 gb of ram on my computer and i have created around 8 VM's which i don't use simultaneously as I use the VM differently.
Now i cannot create any more VM's. I get an error message
No Valid Host was found.
there are not enough hosts available.
Can someone advice what should i do?
Since you say that this is a devstack installation, I'm assuming that you aren't running this in a production environment. Openstack allows users to bump up their over-subscription ratio for the RAM. By default, it is kept at 1.5 times the physical RAM available in the machine. Hence, it should be 12 Gb of usable memory. To change the subscription ratio:
sudo vim /etc/nova/nova.conf
#Add these two lines
ram_allocation_ratio=2
cpu_allocation_ratio=20 # Default value here is 16
These values are just a rough estimate. Change the values around to make them work for your environment. Restart the Devstack.
To check if the changes were made, log into mysql (or whichever DB is supporting devstack) and check:
mysql> use nova;
mysql> select * from compute_nodes \G;
*************************** 1. row ***************************
created_at: 2015-09-25 13:52:55
updated_at: 2016-02-03 18:32:49
deleted_at: NULL
id: 1
service_id: 7
vcpus: 8
memory_mb: 12007
local_gb: 446
vcpus_used: 6
memory_mb_used: 8832
local_gb_used: 80
hypervisor_type: QEMU
disk_available_least: 240
free_ram_mb: 3175
free_disk_gb: 366
current_workload: 0
running_vms: 4
pci_stats: NULL
metrics: []
.....
1 row in set (0.00 sec)
The Scheduler looks at the free_ram_mb. If you have a free_ram_mb of 3175 and if you want to run a new m1.medium instance with 4096M of memory, the Scheduler will end up with this message in the logs:
WARNING nova.scheduler.manager Failed to schedule_run_instance: No valid host was found.
Hence, make sure to keep an eye out for those when starting a new VM after making those changes.
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How do I have to configure a cron job to run every morning at 11:00? I know how to make it run at 11, but not 11:00.
Thanks!
Linux Crontab Format
MIN HOUR DOM MON DOW CMD
0 11 * * * filename
Crontab Fields and Allowed Ranges
MIN Minute field 0 to 59
HOUR Hour field 0 to 23
DOM Day of Month 1-31
MON Month field 1-12
DOW Day Of Week 0-6
CMD Command Any command to be executed
For More info: http://www.thegeekstuff.com/2009/06/15-practical-crontab-examples/
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I setup a CentOS 6.3 setup, on which the console loglevel is set to 4, and default log level is set to 4. I know I can change the default console log level using the following steps:
cat /proc/sys/kernel/printk
4 4 1 7
echo 5 > /proc/sys/kernel/printk
cat /proc/sys/kernel/printk
5 4 1 7
However, upon reboot, the console log level reverts back to the original value. Do I need to recompile the kernel, or is there a way I can get the changed value to be persistent across reboot.
Do I need to recompile the kernel,
No.
or is there a way I can get the changed value to be persistent across reboot.
Yes.
Use the kernel command line parameter loglevel:
loglevel= All Kernel Messages with a loglevel smaller than the
console loglevel will be printed to the console. It can
also be changed with klogd or other programs. The
loglevels are defined as follows:
0 (KERN_EMERG) system is unusable
1 (KERN_ALERT) action must be taken immediately
2 (KERN_CRIT) critical conditions
3 (KERN_ERR) error conditions
4 (KERN_WARNING) warning conditions
5 (KERN_NOTICE) normal but significant condition
6 (KERN_INFO) informational
7 (KERN_DEBUG) debug-level messages
The entire list of parameters possible on the kernel command line are in the Linux/Documentation/kernel-parameters.txt file in the source tree.
Depending on your bootloader (e.g. Grub or U-Boot), you will have to edit text to add this new parameter to the command line. Use cat /proc/cmdline to view the kernel command line used for the previous boot.
Addendum
To display everything, the number supplied for the loglevel parameter would have be be greater than KERN_DEBUG.
That is, you would have to specify loglevel=8.
Or simply use the ignore_loglevel parameter to display all kernel messages.
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Problem Is: Some SFTP connections are failing in customer environment
But using sample code if i test with same server no connection is failed.
may be in customer envi many parallel sftp connection started at a time.
I Want to know what is the meaning of MaxStartups 10:30:60
In the above i know only 10 , which means maximum unauthenticated ssh connection allowed.
means at same time 12 sssh connection request comes 2 request fail and 10 success.
What is the mean of 30 and 60 ?
I Want to know what is the meaning of MaxStartups 10:30:60?
10: Number of unauthenticated connections before we start dropping
30: Percentage chance of dropping once we reach 10 (increases linearly for more than 10)
60: Maximum number of connections at which we start dropping everything