KVM/libvirt: How to disable clock sync for guests? - kvm

is there any possibility to completely disable the clock synchronization for a guest virtual machine? The VM is disconnected from the network but retrieves the current time from the KVM host.
After deleting the line:
<clock offset='utc'>
from the virtual machine's definition file, the line is automatically recreated. Redhat's documentation just handles with the possible offset attributes, but unfortunately not how to disable time sync (Maybe it's not possible?).
Thanks for any advices!

When a guest is booted QEMU needs to initialize the BIOS clock to some value. There's a choice of UTC, localtime (ie UTC adjusted to current timezone), an alternate timezone, or an offset relative to UTC. There's no way to disable BIOS clock initialization altogether. Possible options are described in more detail at http://libvirt.org/formatdomain.html#elementsTime

Related

Splunk 7.2.9.1 Universal forwarder on SUSE Linux12.4 not communicating and forwarding logs to Indexer after certain period of time

I have noticed Splunk 7.2.9.1 Universal forwarder on SUSE Linux12.4 is not communicating to deployment server and forwarding logs to indexer after certain period of time. "splunkd" process appears to be running while this issue persists.
I have to restart UFW for it to resume communication to deployment and forward logs. But this will again stop communication after certain period of time.
I cannot see any specific logs in splunkd.log while this issue occurs.
However, i noticed below message from watchdog.log
06-16-2020 11:51:09.055 +0200 ERROR Watchdog - No response received from IMonitoredThread=0x7f24365fdcd0 within 8000 ms. Looks like thread name='Shutdown' is busy !? Starting to trace with 8000 ms interval.
Can somebody help to understand what is causing this issue.
This appears to be a Known Issue. From the 7.2.9.1 release notes:
Universal Forwarders stop sending data repeatedly throughout the day
Workaround: In limits.conf, try changing file_tracking_db_threshold_mb
in the [inputproc] stanza to a lower value.
I did not find a version where this is not listed as a known problem.

Issue when playing DashCast live stream

I'm trying to capture desktop and stream it live in an Apache server using DashCast. It captures and plays correctly when I do it on demand, however when I do it live and then play with MP4Client it shows only a black screen, not even getting any error message while capturing it. The commands I’m using are:
DashCast -vf x11grab -vres 1280x720 -v :0.0 -npts -live -out /public_html/
And then I play with:
MP4Client http://localhost/vitor/dashcast.mpd
Which results in the following output:
MP4Client http://localhost/vitor/dashcast/dashcast.mpd
Using config file in /home/vitor directory
System info: 11948 MB RAM - 8 cores
Modules Found : 36
Loading GPAC Terminal
[Thread MediaManager] Couldn't set priority(2) for thread ID 0x9b55a700
[Thread MediaManager] Couldn't set priority(2) for thread ID 0x9b55a700
Terminal Loaded in 35 ms
Opening URL localhost/vitor/dashcast/dashcast.mpd
[DASH] Slight drift in UTC clock at time 2015-08-05T12:38:45Z: diff AST - now 3563501 ms
Service Connected
So what am I doing wrong? The client apparently connects correctly to the server, open the player but then it doesn't show anything on screen. I'm using Ubuntu 14.04 with GPAC version 0.5.0.
[DASH] Slight drift in UTC clock at time 2015-08-05T12:38:45Z: diff AST - now 3563501 ms
This message indicates that there is a difference ('slight' is a wrong word here given the actual difference !) between the UTC time indicated in the MPD in the availabilityStartTime attribute and the current time that MP4Client uses to compute which segment to fetch. This is only relevant for live because for on demand, all segments are assumed to be available all the time.
MP4Client uses different strategies to determine the 'current' time. The system time on the client may be different from the system time on the server, if they are using different NTP servers for instance. System time is not reliable. So MP4Client tries to get the time from the server. It first tries to use a specific HTTP "Server-UTC" header that the server may set. See for example this code. If this header is not set, it looks at the HTTP "Date" Header, even if it's not very precise. In your case, your HTTP server probably has a time configuration that does not match the system time. You can tell MP4Client to stop using the server information and to rely on its system time. Since you are using client and server on the same machine, that should work. The documentation of that option is here. For that, use:
MP4Client http://localhost/file.mpd -opt DASH:UseServerUTC=no
Alternatively, you can try to play the MPD locally without going through the web server.
MP4Client file.mpd
If that is not working, open an issue on GPAC's GitHub providing as much information as possible, in particular the result of MP4Box -version.

Twitter APIs - Twitter4j - sync issue?

I am using Twitter4J to retrieve user timelines, but it stopped working. The number of accepted requests is fine, but I get a autentication problem, probably related to clock sync?
INFO: Error while querying Twitter: 401:Authentication credentials (https://dev.twitter.com/pages/auth) were missing or incorrect. Ensure that you have set valid consumer key/secret, access token/secret, and the system clock is in sync.
{"request":"/1.1/statuses/user_timeline.json","error":"Not authorized."}
401:Authentication credentials (https://dev.twitter.com/pages/auth) were missing or incorrect. Ensure that you have set valid consumer key/secret, access token/secret, and the system clock is in sync.
{"request":"/1.1/statuses/user_timeline.json","error":"Not authorized."}
rateLimitStatus=RateLimitStatusJSONImpl{remaining=178, limit=180, resetTimeInSeconds=1432305852, secondsUntilReset=899}, version=3.0.5}
Not sure what to do then. ive tried already to sync my server with ntpdate ntp.ubuntu.com with no luck.
I think you are using SandBox(Build-in VM) of Cloudera/Hortonworks etc
I was also getting the same problem and was trying to sync my clock with 'time.windows.com' clock but I was failed to do. So I moved to 4 nodes cluster which was already existing in my case and there my clock was in sync and I could run my request to Twitter successfully.
Conclusion: Move from Cloudera/Hortonworks VM to own installed OS and make the clock sync.
Hope this help!!!

What do handle_external_interrupt (in vmx.c) do?

In theory, external interrupts of guest VM are injected by KVM through "interrupt window", then what do handle_external_interrupt (in vmx.c) do? From the perspective of source code, it does nothing but recording.
One possible use is to trigger a vmexit for remote guest tlb flush IPIs.
You can check the kvm_vcpu_kick function in the kvm kernel module.

Idle Session in aix

where in AIX is timeot set for a telnet session?
I need to keep each session open indefinitely.
I check the following files
/etc/security/login.cfg
/etc/security/.profile
/etc/profile and my login files
either TMOUT=0 or i remove it form these files, but idle session still went out?
there is any services to start and stop for that?
Thanks
See this Tek-Tip forum post for the same issue.
In short:
check your TMOUT and TIMEOUT environment variables, if set, they could initiate closing of idle sessions
check /etc/security/login.cfg for a shell timeout in "logintimeout"
check your firewall, if it drops idle tcp connections after some time
Maybe you could also configure your clients to send null-packages from time to time to keep sessions alive.
GNU Screen is a more general solution to this problem.