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

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My redis' fork time is slow and impact query performance a little. What should I do to check?

I used redis with RDB option only. It used 2GB of memory. When it forked, it used about 10 seconds to completely save the file. When I check up with redis.io site, I found this latency stat: - Linux ...
1
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0answers
31 views

Can CDN overcome cross country latency?

I have my servers in US while my customers are purely from India. Currently, my customers are facing a latency around (250 - 300ms) If I use CDN for static content caching would it help? My site is ...
1
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2answers
46 views

SMB Latency Issue with Multiple Users

We have a program that works by being shared over the network as a normal Windows Mapped Drive. You run the program from the mapped drive and it stores its files in flat file databases in that mapped ...
28
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7answers
54k views

Why is the response on localhost so slow?

I am working on a tiny little PHP project for a friend of mine, and I have a WAMP environment setup for local development. I remember the days when the response from my local Apache 2.2 was immediate. ...
0
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0answers
28 views

Should I be concerned about AWS inter-zone latency?

I have an app hosted on heroku and I just set up an AWS RDS database. The app and the database are in the same region (US East) but I can't tell whether they are in the same zone or not. Server ...
4
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5answers
3k views

finding the best network latency between two countries

I know there are many tools to test for bandwidth and latency, but they all rely on having at least one host from which you can run those tests. I wonder whether there's an online source or some ...
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4answers
3k views

What kind of latency numbers are reasonable for a corporate network?

I am a software developer and I sometimes want to work from home but to write code over on a VPN is just tortuously slow. I have tried several different things to try and make it more reasonable. On ...
0
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0answers
31 views

Windows Azure VHD Upload Inconsistencies

I'm a little over 2 days deep into a 5 day .vhd upload using the Add-AzureVHD in Windows Azure Powershell and I'm perplexed to the speed (or lack thereof) of this operation. The .vhd is a 300GB file ...
0
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0answers
220 views

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 ...
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3answers
70 views

What network performance is required for thin clients?

I am building a network with approx. 1000 thin clients. I intend to run them over VNC. What type of LAN bandwidth and latency are required? What type of hardware will provide that? If, instead of ...
0
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1answer
66 views

how to choose right SFP 1000BASE-T transceiver? [closed]

I want to connect SFN7122F network card to 1000BASE-T (1 GB cooper Ethernet). I've found a lot of transceiver and I don't understand how should I choose one: ...
0
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2answers
473 views

Why is the latency on one LVM volume consistently higher?

I've got a server with LVM over RAID1. One of the volumes has a consistently higher IO latency (as measured by the diskstats_latency munin plugin) than the other volumes from the same group. As you ...
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3answers
2k views

Terminal server performance over high latency links

Our datacenter and head office is currently in Brisbane, Australia, and we have a branch office in the UK. We have a private WAN with a 768k link to our UK office and the latency is at about 350ms. ...
1
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1answer
149 views

difference between taskset and cpuset

I'm trying to reduce the latency of my linux network application. I've learned that there are two tools for "binding" a program to particular CPU core: taskset and cpuset. Which one should I prefer? ...
0
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0answers
68 views

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 ...
2
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2answers
686 views

Low latency TCP settings on Ubuntu

There is a server for measurements running on Ubuntu in my lab . And there is C program, which receives data through TCP connection and should as soon as possible send a reply. Network latency when ...
-4
votes
1answer
45 views

multiple domains, one static IP address and latency [closed]

how is latency affected when multiple domains are using one single static IP address ? The scenario is in shared web-hosting By latency meaning the DNS lookup the client has to do. As far as I ...
1
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6answers
4k views

MySQL performance over a (local) network much slower than I would expect

MySQL queries in my production environment are taking much longer than I would expect them too. The site in question is a fairly large Drupal site, with many modules installed. The webserver (Nginx) ...
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0answers
19 views

Syncing client and server time for latency comparison

I'm struggling to sync my server's time (an EC2 instance in Dublin) with my local machine. I'm using sudo ntpdate ntp.ubuntu.com to sync my server's time with Ubuntu's time server. I'm then using the ...
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0answers
86 views

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 ...
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1answer
33 views

Users unable to connect due to an unknown plausible reason [closed]

========================= Warning: Long thread; includes a lot of information to give you some basic understanding of my issues. If you rather not read it, then here are my questions: 1) Does Linux ...
0
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0answers
38 views

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 ...
6
votes
1answer
3k views

Limit incoming and outgoing bandwidth and latency in linux

I realise many similar questions have already been asked, but so far I've yet to find a solution to my problem. I have a virtual linux server (running Debian Squeeze) that I use for testing of ...
0
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1answer
137 views

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 ...
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2answers
100 views

Trans-atlantic VOIP

We're a Canadian business on the east coast and will soon be opening up a new call centre in Australia. This new call centre will be handling our graveyard shift and will be overlapping with the ...
4
votes
1answer
787 views

Hyper-V guests: intermittent latency

I am seeing latency on a Hyper-V host and its guests lately. When I run ping -f from a Linux prompt, I see the dots "pulsate" like a heartbeat indicating 2 successive latency spikes within 1 second ...
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0answers
1k views

upstream timed out (110: Connection timed out) while connecting to upstream

I have my backend in France and one of my frontend servers is in Japan. This issue doesn't happen with any other of my frontends, only this Japan server, which already has about 2s latency from most ...
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2answers
122 views

SMB2 over 1GB PTP Link - 10ms latency

Maybe I'm expecting way more from SMB2 than what's realistic. Here is the scenario. Windows 7 Client (Local) A) Win2008R2 Server (LAN -- 1GB, <1ms) B) Win2008R2 Server (WAN -- 1GB, 10ms) ...
1
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1answer
488 views

UDP bandwidth calculation based on packet size, request rate and latency [closed]

I need to estimate the bandwidth for a measurement application to be written that uses UDP. I have a good sense of the numbers but am not sure how to put them together. I checked a few throughput ...
1
vote
1answer
107 views

Network ping replies: latency alternates low and high

I'm experiencing some troubles with one machine in my network. When I ping it the ping replies rotates like this : 64 bytes from 10.0.100.10: icmp_seq=156 ttl=62 time=100 ms 64 bytes from ...
3
votes
1answer
10k views

what is acceptable datastore latency on VMware ESXi host?

Looking at our performance figures on our existing VMware ESXi 4.1 host at the Datastore/Real-time performance data Write Latency Avg 14 ms Max 41 ms Read Latency Avg 4.5 ms Max 12 ms People ...
3
votes
2answers
598 views

Is there anything I can do to decrease waiting time for my static http requests (in chrome's network panel)?

I am running amazon aws ec2 micro instance on Ubuntu 14.04 with apache 2.4.9. The reason for having this instance is just to test and to solve some bugs before rolling up the project. Currently there ...
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2answers
246 views

Apache has a long lag before responding

I have an Apache server on CentOS that occasionally takes 1-5 seconds to serve a file, including a text file that is 2 characters. I have a JMeter test that gets a few different types of files, and ...
3
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1answer
878 views

Diagnose cause of long running requests in IIS 7.0

We are running an ASP.NET web application on IIS 7.0, Windows Server 2008 R2, with SQL Server 2008 R2 for DB. On weekends, when the traffic is high, the request queue length in the IIS servers ...
0
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2answers
248 views

How can I determine the fastest memory based on latency and bandwidth?

I've got some older hardware that needs a memory upgrade, and I was trying to determine what RAM would be the fastest on the platform. My platform takes DDR2 667MHz which is (slightly) more ...
4
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2answers
401 views

Why do tracert latencies not add up to ping latency?

One might expect the sum of the tracert latencies to equal 267ms:
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votes
4answers
493 views

Network Latency over WAN

Let me take a minute to explain the background of the challenge I am facing. My company has offices in US and Asia. The users work on large CAD files. The office in US has NAS (Network Attached ...
0
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0answers
20 views

Email duplicated from Barracuda Cloud layer?

Incoming email to our domain first goes to the Barracuda Cloud Protection Layer before being passed to our local Barracuda 300 antispam appliance. It then goes to our email server (CommuniGate). ...
2
votes
2answers
223 views

exchange accounts on outlook 2010 freeze randomly due to high latency

One of our clients is running a windows SBS server 2011, with users in both a TS environment and local lan computer access. This is a small environment with approximately 35 users. The symptoms we ...
1
vote
1answer
472 views

Amazon EC2 and Amazon RDS in Same Network

We have deployed our application in EC2 instance and our database is in RDS which is db.m2.2xlarge. I see some minor slowness in our application when compare to our QA environment where has both ...
10
votes
4answers
5k views

Why do mobile networks have high latencies? How can they be reduced?

I'm increasingly seeing mobile networking technologies being used to get internet access in areas where it is otherwise not available. While mobile networking is usually not yet viable as the primary ...
0
votes
1answer
187 views

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 ...
3
votes
3answers
507 views

Network Latency and Timing as shown by Chrome

I'm trying to understand why a static image being served by IIS is taking ~ 182 ms to load. Using chrome I captured the following timing information. When I request the same image by opening ...
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votes
1answer
52 views

Dedicating a server for latency test

I've created a server to test bandwidth from employees working remote (using speedtest.net mini), but was wondering if anyone knew of a way to setup some software in linux to test latency and possibly ...
1
vote
1answer
66 views

Microwave Link Latency

An internet provider installed us a microwave link: The issue is that: The ping from our side to the gateway is about 1-2 ms, which is great, but it remains like this for only 12 hours, then it ...
0
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2answers
153 views

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 ...
0
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2answers
42 views

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 ...
0
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2answers
835 views

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 ...
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0answers
54 views

Jitter Calculation

I have recently come across the term Jitter in the RFC3550 [page 40]. I have a question regarding this, that what if I add all the Jitter(J) values that I get after receiving each packet and in the ...
3
votes
2answers
3k views

sssd and ldap authentication cache

On our box running OpenSUSE 12.2 we have installed OpenLDAP and sssd daemon. We are using these two services for user authentication. Recently we created a script which creates new web-users for our ...