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Questions tagged [latency]

Latency is the time period between a signal being sent and a signal being received

Latency is the time period between a signal being sent and a signal being received. In computer networking this can be the time between a sending of a packet and receiving of a packet.

To illustrate we can use the ping command:

PING google.be (173.194.66.94) 56(84) bytes of data.
64 bytes from google.be (173.194.66.94): icmp_req=1 ttl=47 time=76.6 ms
64 bytes from google.be (173.194.66.94): icmp_req=2 ttl=47 time=74.8 ms
64 bytes from google.be (173.194.66.94): icmp_req=3 ttl=47 time=79.6 ms

The latency here is 76.6 ms.

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OpenVPN + Scrambled patch on Amazon EC2

Yesterday I deployed a regular OpenVPN installation on Debian Squeeze / Amazon EC2. The VPN server is in Singapore and I connect to it from China Mainland. Later on, after some tests I had to start thinking on patching OpenVPN with the "Scrambled"…
Chroma Funk
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MySQL replication across availability zones in AWS resulting in lag

I have 3 EC2 instances, each running MySQL. 2 are slaves replicating from the master. The master is located in the availability zone eu-west-1b. One of the slaves is in the same zone, and the other is in eu-west-1a. The slave located in eu-west-1a…
Outspaced
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Lotus Notes Error - "Specified Network name no longer available"

I work for a bank who is using Lotus Notes email and during the transition from Windows XP to Windows 7 the Lotus Notes client was upgraded from Client 8.0.2 to 8.5.3. Given that these were the only two things that changed, our clients now randomly…
nullByteMe
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Why is my server so slow to accept connections?

I've noticed that my server seems to be very slow to accept connections - i.e. when analyzing the load time using the Chrome event map, it shows that some tasks can spend multiple seconds waiting for the server to accept a connection. For example…
Sam Heather
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How do I troubleshoot latency issues with elastic load balancer (ELB) in Amazon AWS?

We have a web app and API hosted at Amazon AWS, with three environments - development (dev), testing/staging (uat), and live. Each environment has a load balancer, two EC2 instances and an RDS database. We're relatively new to AWS and learning as we…
Dylan Beattie
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How to investigate initial server response latency (2.9s) of wordpress/nginx site?

I infer it takes roughly 3 seconds to build HTML and send it back. Is there something obvious that I am missing? Hardware: 2 CPU, 4 GB RAM, 100 gb HDD Stack: Fresh CentOS, Nginx, Wordpress DD perf averages 200-300 MB/s EDIT: Getting "Unable to…
Thale
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How do I choose servers to minimize latency to a critical third-party service?

I would like to spin up a cloud server that has the minimum possible ping to a third-party service. Do you just get on AWS and keep making servers in new Availability Zones until the ping is good enough? Are there easier ways to do this? Am I likely…
Christian Oudard
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ESXi - What could be the cause of high write latency on a local datastore?

I have a ESXi 5.5 server and I'm experiencing high write latency on a local datastore. This datastore is on a virtual disk provided by a RAID card (two SATA disks on RAID 1). When I copy large files, it takes ages to complete the transfer and write…
mimipc
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Amazon Ec2 with LAMP and RDS: how to easely replicate in different regions

I'm a newbie about Amazon cloud and I need an help in order to reduce the geographically latency of a website. I have an Amazon Ec2 with LAMP and RDS in EU Irland. I wish to have the same information (php files, css, images, database, ...) on new…
Luca
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CentOS Latency High Troubleshooting

I have two CentOS servers connected via a 10 Gb fiber optic cable with a network emulator connected between them. All three units sit on a desk in the lab. There is also a regular 1 Gbit Ethernet cable connected to each of the machines, which…
Sarah Weinberger
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Why my 2nd ip from traceroute is not answering the ping anymore?

My Internet is really laggy today, I did a tracerout and I realize that I'm having no answer from an ip at the beginning of the traceroute. see: Tracing route to 12.129.202.154 over a maximum of 30 hops 1 <1 ms <1 ms <1 ms 192.168.0.1 …
Pedro77
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Unexplained Packets being dropped

I have two servers one sending large amounts of data to the other, we are noticing that one server is sending data to the other but the receiving server is missing some of the data or packets. I am currently comparing nic's they are setup as…
JJJJNR
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Unicorn rails server with Apache

I'm looking for the best setup to use in conjunction with Unicorn. Are there clear advantages or disadvantages to using Unicorn rails server with Apache? Should I consider using NGINX? I'm concerned most with low latency, and my current setup has…
JZ.
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Is it bad for latency to have ping running 24/7?

I want to display my avg latency time for whatever connection I currently have to the internet in a widget. Would having ping run continuously make my connection suffer?
Elijah Lynn
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35 times increased latency between data send rate of 1 millisecond vs 100 microseconds. WHY?

Experiment hping -S --data 100 -c 100 10.56.1.2 -i u100 round-trip min/avg/max = 0.5/14.0/15.8 ms hping -S --data 100 -c 100 10.56.1.2 -i u1000 round-trip min/avg/max = 0.3/0.4/4.8 ms Observation: When the packet send rate increases from 1…
Vikas kedia
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