Sysadmin tips
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Sysadmin tips
Tips and Tricks that we have to know and abuse every day. sysadmin, sysops and network.
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Home of Sysadmin & Sysops tips and tricks

Home of Sysadmin & Sysops tips and tricks | Sysadmin tips | Scoop.it

Commands, tips, network config, bigdata, performance tweaking, all you need to know.

stephane gault's insight:

MySQL, Percona, HAproxy, Nginx, Zsh, Cassandra, Hadoop, Memcached, Redis, ElasticSearch, Postfix, OpenDKIM, etc ...

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HAProxy's load-balancing algorithm for static content delivery with Varnish

HAProxy's load-balancing algorithm for static content delivery with Varnish | Sysadmin tips | Scoop.it
HAProxy's load-balancing algorithms HAProxy supports many load-balancing algorithms which may be used in many different type of cases. That said, cache servers, which deliver most of the time the s...
stephane gault's insight:

Very clever use of HAProxy to deliver faster and smarter ! HAProxy to optimize the resources on the cache, mainly its memory, in order to improve the HIT rate with Varnish.

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How We Scale VividCortex's Backend Systems

How We Scale VividCortex's Backend Systems | Sysadmin tips | Scoop.it
This is guest post by Baron Schwartz, Founder & CEO of VividCortex, the first unified suite of performance management tools specifically designed for today's large-scale, polyglot persistence tier.
stephane gault's insight:

Another Great content by Baron Schwartz on VividCortex scalabilty approach. 

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How and Why Swiftype Moved from EC2 to Real Hardware

How and Why Swiftype Moved from EC2 to Real Hardware | Sysadmin tips | Scoop.it
This is a guest post by Oleksiy Kovyrin, Head of Technical Operations at Swiftype. Swiftype currently powers search on over 100,000 websites and serves more than 1 billion queries every month.
stephane gault's insight:

Well, obviously you also can move OUT of EC2 ! This is a very good post of why and how they manage it. I'm not the biggest fan of full "cloud" infrastructure for the exact same reasons !

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The Architecture of Algolia’s Distributed Search Network

The Architecture of Algolia’s Distributed Search Network | Sysadmin tips | Scoop.it
Guest post by Julien Lemoine, co-founder & CTO of Algolia, a developer friendly search as a service API.
Algolia started in 2012 as an offline search engine SDK for mobile.
stephane gault's insight:

Scalability : The main goal of alot of infrastructure, and the dilema of the consistency vs HA vs performances : the CAP theorem.

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How to setup a PXC cluster with GTIDs (and have async slaves replicating from it!)

How to setup a PXC cluster with GTIDs (and have async slaves replicating from it!) | Sysadmin tips | Scoop.it

This past week was marked by a series of personal findings related to the use of Global Transaction IDs (GTIDs) on Galera-based clusters such as Percona XtraDB Cluster (PXC).

stephane gault's insight:

Very complete setup guide to PXC. Clever use of Global Transaction IDs (GTIDs) on Galera-based clusters such as Percona XtraDB Cluster.

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MySQL table Point-in-Time-Recovery from mysqldump backup | FromDual - MySQL, Galera Cluster, MariaDB and Percona Server support, SLA and services

MySQL table Point-in-Time-Recovery from mysqldump backup | FromDual - MySQL, Galera Cluster, MariaDB and Percona Server support, SLA and services | Sysadmin tips | Scoop.it
stephane gault's insight:

Very handy indeed !

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How small changes impact complex systems – MySQL example

How small changes impact complex systems – MySQL example | Sysadmin tips | Scoop.it
If you’ve been studying complex systems you know what minor changes might cause consequences of much greater proportions, sometimes causing some effects that are not easily explained at first.
stephane gault's insight:

Very nice analysis on what can hide changes and history list.

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Making HAProxy 1.5 replication lag aware in MySQL

Making HAProxy 1.5 replication lag aware in MySQL | Sysadmin tips | Scoop.it
HAProxy is frequently used as a software load balancer in the MySQL world. Peter Boros, in a past post, explained how to set it up with Percona XtraDB Cluster (PXC) so that it only sends queries to available nodes.
stephane gault's insight:

Ha proxy Failover aware of Replication lag is mandatory ...

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MySQL thread status: Waiting for query cache lock

MySQL thread status: Waiting for query cache lock | Sysadmin tips | Scoop.it

MySQL thread status: Waiting for query cache lock. Waiting for query cache lock is a connection status specific to MySQL 5.5 or newer...

stephane gault's insight:

Beware of this new feature in MySQL 5.5 or newer. We've learn the hard way, that it can be a killer on your performance at some point in a high concurrent query environnement. When you start to see some logs with : "Waiting for query cache lock", it may be time for disable it totaly !

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Avoiding MySQL ALTER table downtime

Avoiding MySQL ALTER table downtime | Sysadmin tips | Scoop.it
MySQL table alterations can interrupt production traffic causing bad customer experience or in worst cases, loss of revenue. Not all DBAs, developers, syadmins know MySQL well enough to avoid this pitfall.
stephane gault's insight:

ALTER table operations are always a pain on big tables, résulting in downtimes. Here is a good insight of how it can be done.

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How to deal with MySQL deadlocks

How to deal with MySQL deadlocks | Sysadmin tips | Scoop.it
A deadlock in MySQL happens when two or more transactions mutually hold and request for locks, creating a cycle of dependencies. In a transaction system, deadlocks are a fact of life and not completely avoidable.
stephane gault's insight:

deadlocks is like prime evil !

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MySQL Replication: ‘Got fatal error 1236′ causes and cures

MySQL Replication: ‘Got fatal error 1236′ causes and cures | Sysadmin tips | Scoop.it
MySQL replication is a core process for maintaining multiple copies of data – and replication is a very important aspect in database administration.
stephane gault's insight:

Very handy, you will face this error at least one time on replication.

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Problems connecting to servers behind (Cisco) firewalls VPN using ssh

Problems connecting to servers behind (Cisco) firewalls VPN using ssh | Sysadmin tips | Scoop.it

After upgrading to Natty Narwhal I couldn't connect to my Linux based jump host (connected via VPN) ...

stephane gault's insight:

Derping with ssh behind cisco VPN annyconnect ... Always a pleasure to work behind those ... Workaround is trully DERP ;)

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Better Parallel Replication for MariaDB and MySQL | MariaDB

Better Parallel Replication for MariaDB and MySQL | MariaDB | Sysadmin tips | Scoop.it
Parallel replication is a much-expected feature of MySQL. It’s available in MariaDB 10.0 and in MySQL 5.7. Yet, both lose efficiency when replicating through intermediate masters. In this post, we’ll explain how parallel replication works and why it does not play well with intermediate masters. We’ll also offer a solution (hint: it involves Binlog Servers).
stephane gault's insight:

Parallel replication taking advantage of the binary log group commit optimization. Well expected feature !

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Will Automated Alerting Replace the NOC? - PagerDuty

Will Automated Alerting Replace the NOC? - PagerDuty | Sysadmin tips | Scoop.it
Solutions like PagerDuty improve your Network Operations Center performance. Here are five ways our customers use PagerDuty to enhance their NOCs.
stephane gault's insight:

Clever article on the synergy of alerting with real human actions.

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Cassandra Migration to EC2 - High Scalability -

Cassandra Migration to EC2 - High Scalability - | Sysadmin tips | Scoop.it

Guest post by Tommaso Barbugli the CTO of getstream.io about cassandra migration on EC2

stephane gault's insight:

very useful feedback on how to handle the switch from your own infrastructure to the EC2 ecosystem for cassandra. Going multi datacenter is always a real challenge !

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Query Optimization with MySQL 5.7 and MariaDB 10: Even newer tricks

Tutorial delivered at Percona Live London 2014, where we explore new features and techniques for faster queries with MySQL 5.6 and 5.7 and MariaDB 10, includin…
stephane gault's insight:
Query Optimization with MySQL 5.7 and MariaDB 10
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MySQL benchmarks on eXFlash DIMMs

MySQL benchmarks on eXFlash DIMMs | Sysadmin tips | Scoop.it
In this blog post, we will discuss MySQL performance on eXFlash DIMMs. Earlier we measured the IO performance of these storage devices with sysbench fileio.EnvironmentThe benchmarking environment was the same as the one we did sysbench fileio in.
stephane gault's insight:

Great benchmark, with all those new storage techno, you have to figure what you'll really need before requesting a quote. IBM eXFlash and FuisionIO great storage card on the grill !

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Hyper-threading – how does it double CPU throughput?

Hyper-threading – how does it double CPU throughput? | Sysadmin tips | Scoop.it
The other day a customer asked me to do capacity planning for their web server farm.
stephane gault's insight:

Back in the days, when HT came out on Xeon (P4 based), as a GSP (Game service provider) you where forced to turn HT off to get good response time, and max Frames. Well ... not much have changed :)

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The MySQL Query Cache: How it works, plus workload impacts (good and bad)

The MySQL Query Cache: How it works, plus workload impacts (good and bad) | Sysadmin tips | Scoop.it
Query caching is one of the prominent features in MySQL and a vital part of query optimization. It is important to know how it works as it has the potential to cause significant performance improvements – or a slowdown – of your workload.
stephane gault's insight:

As we learned the hard way, MySQL query cache can be a huge bottleneck !

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Faster restarts for MySQL and Percona Server 5.6.21+

Faster restarts for MySQL and Percona Server 5.6.21+ | Sysadmin tips | Scoop.it

By default in MySQL 5.6, each time MySQL is started (regular start or crash recovery), it iterates through all the binlog files when GTIDs are not enabled ...

stephane gault's insight:

MySQL 5.6 fix for faster start of Percona/MySQL server. 

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How a set of queries can be killed in MySQL using Percona Toolkit’s pt-kill

How a set of queries can be killed in MySQL using Percona Toolkit’s pt-kill | Sysadmin tips | Scoop.it
You might have encountered situations where you had to kill some specific select queries that were running for long periods and choking the database. This post will go into more detail with an example of report query offloading.
stephane gault's insight:

Very handy tool

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Three Reasons You Probably Don’t Need Multi-Data Center Capabilities

Three Reasons You Probably Don’t Need Multi-Data Center Capabilities | Sysadmin tips | Scoop.it
This is a guest post by Nikhil Palekar, Systems Architect, FoundationDB.  For many organizations that care a lot about strong consistency and low latency or haven’t already built a fault tolerant application tier on top of their database, adding...
stephane gault's insight:

Very intresting point of view.

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How League of Legends Scaled Chat to 70 million Players - It takes Lots of minions.

How League of Legends Scaled Chat to 70 million Players - It takes Lots of minions. | Sysadmin tips | Scoop.it
How would you build a chat service that needed to handle 7.5 million concurrent players, 27 million daily players, 11K messages per second, and 1 billion events per server, per day?
What could generate so much traffic?
stephane gault's insight:

Very intresting xp shared on this one ( this game is really nice btw ).

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Linux Terminal: An lsof Primer

Linux Terminal: An lsof Primer | Sysadmin tips | Scoop.it
Article by Daniel Miessler first posted on his blog lsof is the sysadmin/security über-tool.
stephane gault's insight:

"lsof" very handy tool explained with exemples.

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