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Previous 30 Newer Entries Showing entries 31 to 60 of 1115 Next 30 Older Entries

Displaying posts with tag: Linux (reset)

#DBHangOps 9/17/13 — Data Warehousing, MySQL-isms, and MySQLConnect!
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And that’s a wrap! Check out the recording:

Hello!

Coming up this Wednesday, September 18th, 2013 at 12:00pm pacific (19:00 GMT) come and join #DBHangOps to discuss:

  • Data warehousing in MySQL
    • Shipping large tables from production to your Data warehouse
    • Do you use Federated engine?
    • What other solutions do you use?
  • Answer some questions about MySQL-isms (requested by Tim Callaghan)
    • Why does MySQL have FRM files instead of storing them in a data dictionary table?
    • Why doesn’t InnoDB support other page sizes?
    • Why do we store data in a master.info file?
  • What are you excited to see at MySQLConnect?

As always, take a


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Limit The Size of Your Core Files on Linux
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So we all know that when troubleshooting MySQL crashes or any other processes in that regard, we simply enable core files to be dumped when the appropriate signal it triggered. To get the best results, we’d set the core file size limit everywhere to unlimited and be done with it, but what if you want to limit that to a certain size? I stumble to a small confusion lately when doing this for MySQL, so let me share quickly.

First, for MySQL, mysqld_safe would use ulimit to set the core-file-size value you pass to it. Now remember according to the manual, this value should be in blocks (some documentation says its in chunks of 1024 bytes). However, according to my experience on CentOS 6, this is the physical block size of the device where your core_pattern is pointed to.

[root@centos6 ~]# ulimit -a
...
core file size          (blocks, -c) 0
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#DBHangOps 9/4/13 — Data dictionary corruption, MySQL Utilities, Benchmarking, and MySQLConnect!
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Check out the video!
Hey there everybody!

Coming up this Wednesday, September 4th, 2013 at 12:00pm pacific (19:00 GMT) take part in #DBHangOps to discuss:


  [Read more...]
Trick: recovering from "no space left on device" issues with MySQL
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Just read Ronald Bradford's post on an unnecessary 3am (emergency) call. I sympathize! Running out of disk space makes for some weird MySQL behaviour, and in fact whenever I encounter weird behaviour I verify disk space.

But here's a trick I've been using for years to avoid such cases and to be able to recover quickly. It helped me on such events as running out of disk space during ALTER TABLEs or avoiding purging of binary logs when slave is known to be under maintenance.

Ronald suggested it -- just put a dummy file in your @@datadir! I like putting a 1GB dummy file: I typically copy+paste a 1GB binary log file and call it "placeholder.tmp". Then I forget all about it. My disk space

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#DBHangOps 8/21/13 — Fractal indexes in TokuDB and Schema tracking
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Hey all!

Coming up this Wednesday, August 21st, 2013 at 12:00pm pacific (19:00 GMT) join in to talk about:

  • Gerry from Tokutek to talk about B-Tree indexes in InnoDB and fractal indexes TokuDB!
  • Schema Versioning
    • How do you manage schema versions in your development pipeline?
    • How are your schema changes deployed? Is it automated?
    • Some automated schema management tools:
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Tool of the day: q
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If you work with command line and know your SQL, q is a great tool to use:

q allows you to query your text files or standard input with SQL. You can:

SELECT c1, COUNT(*) FROM /home/shlomi/tmp/my_file.csv GROUP BY c1

And you can:

SELECT all.c2 FROM /tmp/all_engines.txt AS all LEFT JOIN /tmp/innodb_engines.txt AS inno USING (c1, c2) WHERE inno.c3 IS NULL

And you can also combine with your favourite shell commands and tools:

grep "my_term" /tmp/my_file.txt | q "SELECT c4 FROM - JOIN /home/shlomi/static.txt USING (c1)" | xargs touch

Some of q's functionality (and indeed, SQL functionality) can be found in command line tools. You can use grep for pseudo

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Public DNS resolve for VM instances hosted at OpenStack nova compute grizzly edition
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Issue – the OpenStack instances hostnames are not resolved at the moment by their floating IPs.

Fast solution – use PowerDNS
Short story:
1. Boot an instance , assign it a floating IP, open tcp ports 22 8001 and udp port 53.
2. Install PowerDNS, the particular yum package is named pdns.
3. install the mysql backend for PowerDNS, its available as yum package as well.
4. Install MariaDB , set the proper configuration, the initialize it at the default location.
5. Set the pdns user, create the pdns database and create the tables needed.
6. Configure the pdns service to use the gmysql backend.
7. Create and user at the OpenStack MySQL able to connect from the floating IP subnet.
8. Grant that user select permissions on all nova.* tables.
9. At the PowerDNS









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#DBHangOps 7/24/13 — Innobackupex, schema migrations, and more!
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And all set. Check out the recording:

Hello everybody!

Coming up this Wednesday, July 23rd, 2013 at 12:00pm pacific (19:00 GMT) join in to hear:

  • Brandon Johnson from Mozilla talk about an issue he recently worked through with XtraBackup and the process he took to identify and resolve the issues.

And also take part in discussion around:

  • How do you apply production schema changes?
    • Do you use pt-online-schema-change?
      • Issues to watch out for
    • Just run the alter!
    • Pull from a pool and apply

Make sure to follow the #DBHangops twitter search, the DBHangops Twitter Feed, or this blog post to get a link for the google hangout on Wednesday!

Excited to see all of you joining in on the conversation!

#DBHangOps 7/10/13 — Plugins, Kernel Settings, and THP!
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All set, here’s the recording!

Hey there everyone!

Another informative and fun-filled #DBHangOps coming up this Wednesday, July 10th, 2013 at 12:00pm pacific (19:00 GMT). Join the discussion and contribute your experience on the following topics!

  • Plugins for MySQL
    • Which do you use?
    • Are there plugins that you want?
  • Kernel Parameters in Linux for MySQL, specifically:
  • InnoDB buffer pool size and settings
    • What works in your environment and why?
  • And If there’s time, information about the TokuDB storage engine in MariaDB!

Make


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Scalability Happiness – A Quiet Query Log
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Join 7500 others and follow Sean Hull on twitter @hullsean.

There’s a lot of talk on the web about scalability. Making web applications scale is not easy. The modern web architecture has so many moving parts. How can we grapple with the underlying problem?

Also: Why Are MySQL DBAs So Hard to Find?

The LAMP stack scales well

The truth that is half right. True there are a lot of moving parts, and a lot to setup. The internet stack made up of Linux, Apache, MySQL & PHP. LAMP as it’s called, was built to be resilient, dynamic, and scalable.

  [Read more...]
#DBHangOps 6/26/13 — Common_Schema, Plugins, Kernel Params, and more!
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#DBHangOps for 6/26/13 is all done! Check out the recording below:

Hey everybody!

#DBHangOps is back this week at a slightly earlier time this Wednesday, June 26th, 2013 at 11:00am paciifc (18:00 GMT) . We’ll have special guest Shlomi Noach talking about the open source tools he’s developed to improve a DBA’s day-to-day work.

Be sure to check out the #DBHangops twitter search, the DBHangops Twitter Feed, or this blog post to get a link for the google hangout on Wednesday!

Thanks and see all of you there!

mylvmbackup 0.14 has been released
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It's my great pleasure to announce the release of mylvmbackup version 0.14.

This release includes a large number of improvements, code cleanups, and new functionality.

I would like to thank Ask Bjørn Hansen, Ben Bonnel, Norbert Tretkowski, Neil Wilson, Klaus Ethgen and Alexandre Anriot for their feedback and contributions to this release.

The release is available as a source tarball and generic RPM package. Packages for other distributions are available from the openSUSE Build Service.

Some notable highlights from the ChangeLog

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#DBHangOps 6/12/13 — Patches, Python, and Migrations!
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Annnd all set! Check out the recording for the topics below:

Hello everyone!

We missed out on the last meeting time for #DBHangOps due to some conflicts, but we’re looking to come back strong this Wednesday, June 12th 2013 at 12:00pm pacific (19:00 GMT). Come join the discussion and contribute your experience on:

  • Upgrading to MySQL 5.6
    • Any issues or gotchas?
  • MySQL Python Utilities
    • How do you use them?
  • MySQL patches
    • Patches you use
    • Patches you want
  • Interesting or valuable Linux kernel settings

Be sure to check out the #DBHangops twitter search, the DBHangops Twitter Feed, or this blog post to get a link for the google hangout on Wednesday!

Looking forward to seeing you all there!

The network is reliable
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A fascinating post-mortem on high profile network failures:

This post is meant as a reference point–to illustrate that, according to a wide range of accounts, partitions occur in many real-world environments. Processes, servers, NICs, switches, local and wide area networks can all fail, and the resulting economic consequences are real. Network outages can suddenly arise in systems that are stable for months at a time, during routine upgrades, or as a result of emergency maintenance. The consequences of these outages range from increased latency and temporary unavailability to inconsistency, corruption, and data loss. Split-brain is not an academic concern: it happens to all kinds of systems–sometimes for days on end. Partitions deserve serious consideration.

MariaDB in Red Hat Software Collections
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Towards the end of last year, I was asked to investigate the Red Hat Software Collections by someone that popped by one of my talks. SkySQL has been working heavily with Red Hat, and with Fedora 19 shipping MariaDB as a default, it seems like MariaDB is getting even more distribution. The Red Hat Software Collections 1.0 Beta is now available for users of Red Hat Enterprise Linux 6.

From a database standpoint, users now get MariaDB 5.5. I encourage all to try it, as it is an in-situ upgrade. It is described as:

MariaDB version 5.5, which introduces an easy-to-adopt

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MySQL PAM and Active Directory authentication
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How-To configure your MySQL to use PAM and/or Active Directory authentication with percona-pam-authentication plugin.
Continuing articles about Two-Factor authentication or integrating Linux services with Active Directory, this How-To is one of my recent works that I have done these days, so I hope it may help the community with this guide to configure MySQL with PAM and subsequently using Active Directory to authenticate. If you are new here, please refer to SSH Two-Factor authentication, which explains how to install likewise and integrate your Linux with AD. However, we will have few exceptions to get MySQL working  [Read more...]
MySQL Backups, The Tools So Far
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Backups is one of the most important part of any MySQL deployment, and nowadays, there’s a number of tools to choose from depending on how your organization implements them. The purpose of this post is to enumerate the main tools and some helpers that makes backing up and testing/restoring your backups more convenient. By all means this is not the complete list, I’m sure I am missing some, so feel free to add them through the comments.

The Core Tools

  • mysqldump – is a logical backup tool for MySQL. It creates plain text files with SQL statements which you can directly import back to the server. Some would say mysqldump is not really a backup tool as you cannot get a consistent backup without disrupting operations while the server is running. I’d say this is
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ZFS on Linux and MySQL
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I am currently working with a large customer and I am involved with servers located in two data centers, one with Solaris servers and the other one with Linux servers. The Solaris side is cleverly setup using zones and ZFS and this provides a very low virtualization overhead. I learned quite a lot about these technologies while looking at this, thanks to Corey Mosher.

On the Linux side, we recently deployed a pair on servers for backup purpose, boxes with 64 300GB SAS drives, 3 raid controllers and 192GB of RAM. These servers will run a few slave instances each of production database servers and will perform the backups.  The write load is not

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Some LSI 9211-8i issues on Windows and Linux
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tl;dr:
Make sure you flash an LSI-9211 to IT firmware rev#14 to get it to work 
with Linux and SSD trim.  You may have to downgrade from newer firmware
to older firmware to get the card to work.


Finding a SATA III controller with more than one PCI-e lane
After a recent hardware issue I decided to upgrade my computer to use new Intel 520 120MB SSD drives in RAID for improved performance.  The motherboard I use (an ASUS Rampage III extreme) has a Marvel SATA III controller with two ports, but I discovered that it is connected via only a single PCI-e lane (each lane can do at most 400MB/sec*).  This means that it can't effectively support even a single Intel 520 because one device can saturate the SATA III bus (An Intel 520 is rated at up to 550MB/sec sequential write).

So I went on a quest for a new SATA 3 controller.   To




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#DBHangops for 5/15/13 — Filesystems, monitoring, settings, Oh my!
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Here’s the recording!

Heyo!

Now that we’ve gone through the Percona Live MySQL Conference and Expo review and had an amazing turnout to talk about it, it’s time to open up the discussion around things that DBAs want to talk about and need to be conscientious of. Join us on Wednesday at 12:00pm PDT (19:00 GMT) to take part in the discussion and share your knowledge and experience with the following topics:

  • Filesystems and MySQL — Which do you use and why?
    • Do you handle I/O alignment? How do you do it?
    • Scheduler changes?
  • Nagios checks! — Any new checks you’ve added recently?
  • The worst settings in MySQL that you always change
  • What are the most important variables to you,

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Storage caching options in Linux 3.9 kernel
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dm-cache is (albeit still classified “experimental”) is in the just released Linux 3.9 kernel. It deals with generic block devices and uses the device mapper framework. While there have been a few other similar tools flying around, since this one has been adopted into the kernel it looks like this will be the one that you’ll be seeing the most in to the future. It saves sysadmins the hassle of compiling extra stuff for a system.

A typical use is for an SSD to cache a HDD. Similar to a battery backed RAID controller, the objective is to insulate the application from latency caused by the mechanical device, the most laggy part of which is seek time (measured in milliseconds). Giventhe  relatively high storage capacity of an SSD (in the hundreds of GBs), this allows you to mostly disregard the mechanical latency for writes and that’s very useful for

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2013 MySQL Conference and Expo — a #DBHangOps Review
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Hey everybody!

The Percona Live MySQL Conference and Expo just wrapped up last week and we’re looking to get some conference in review talk from everyone! Talk about your favorite sessions, new things you learned, and your overall opinion of the conference!

Hop online Wednesday at 12:00pm PDT (19:00 GMT) to join the discussion and share your experience from the 2013 Percona Live: MySQL Conference and Expo.

Be sure to watch this twitter search or this blog post get a link for the google hangout tomorrow!

Some talks that were specifically called out:

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Connecting your Linux to a Cisco AnyConnect (SSL) – part 3
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Hi there !

 

This is the final part of using openconnect  - You can check the older ones below:

http://www.heitorlessa.com/connecting-your-linux-to-a-cisco-anyconnect-ssl-part-1/

http://www.heitorlessa.com/connecting-your-linux-to-a-cisco-anyconnect-ssl-part-2/

 

As mentioned previously, we will be covering here:

  • How to create a script to monitor such VPN using ICMP, and restart that VPN if it is down

 

I would say, this is very straight forward and does not require much knowledge, so we are going to follow the same procedure as part 2 – Show the script in


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Connecting your Linux to a Cisco AnyConnect (SSL) – Part 2
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Hey you!

As said in the part 1 of this article, I will be covering here:

  • How to create a openconnect init script

So, concerning the init script I will be posting parts of the script first, and then will put a link for download at the end.

First of all, we need the shebang (#!/bin/bash) and then global variables that will be used along the script:

# Path variables
PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"

# VPN Variables
IFACE="sslvpn"
VPN_USER="vpn_user"
VPN_HOST="sslvpn.yourdomain.com"
VPN_PASS="vpn_password"
PID="/var/run/openconnect.pid"
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Check (Rough) Progress of Your CSV Import to MySQL
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If you are importing large CSV or SQL dumps to MySQL, chances are you were looking for ways to see how far the import has gone. If you know how many rows there are from the file being imported, you can do a SELECT COUNT(*) but that would take sometime for the query to finish especially on really big imports.

Using lsof, you can monitor the current file offset to which a process is reading from using the -o option. Knowing the size of the file and some snapshots of the offset, you can get a somewhat rough idea of how fast the import goes. Note though that this is only file-read-pace not actual import speed as MySQL import can vary depending on a number of conditions i.e. table growth, secondary indexes, etc.

Let’s say I am importing a 1.1G CSV file into a table.

[revin@forge msb_5_5_300]$ ls -al
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How To Run Your Own Web SMS Portal With PointSMS
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How To Run Your Own Web SMS Portal With PointSMS

This tutorial will show you how you can set up an SMS web site on CentOS using PointSMS.

#DBHangOps 3/27/13!
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Hi everyone!

Here’s a video of this week’s #DBHangOps:

March 27th at 12:00pm PDT (19:00 GMT) is when the next #DBHangOps is gonna go down. Check out the twitter search and hop on the google hangout to contribute some discussion! This week’s topics are:


  [Read more...]
How to fix the Percona repo failure when installing Percona Toolkit
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Here’s a solution to the not-so-long-standing issue of the Percona yum repo being broken for the CentOS 6 x86_64 version of the Percona-toolkit package. The repo listing is reporting an older version of the RPM which is not available on the site, so to fix this you just have to download the newer file and tell yum to add it locally. The side benefit is that you can use Yum to manage the RPM without adding the Percona repo, since the default settings for their repo could/have/had caused conflicts with Base Repo versions of MySQL packages; the Percona repo instructions set ‘enabled=1′ — not a great idea if you’re not setup to use the Yum priorities method of repo weighting.

So, if you see this after installing the repo via the instructions on their site:
Downloading Packages:


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Cloudflare, now offering to be your Single Point of Failure
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There have been many articles about the downtime issue with Cloudflare last week, so I won’t get into the technical details of that. However, there’s the fine print to remember. Consider this a subtle reminder that core Internet infrastructure services like Cloudflare’s DNS-based “Always Online” caching and packet inspection security services do not come with Service Level Agreements even at the “Pro” account level. Even with a Pro account you are paying for a service with no uptime guarantee and you must only hope that it resolves your sites the majority of the time. This is fine, this is what the contract says: no SLA unless you pay for the Business account. An odd naming convention given that most Professionals are using their websites for business and would want the SLA, but I digress.

So,

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openSUSE 12.3 released with MariaDB as default
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Congratulations to the openSUSE community on a successful release of openSUSE 12.3. A highlight worth mentioning is that MariaDB is now the default as opposed to MySQL. What are you waiting for, download it!

From the features list, here’s an excerpt focusing on MariaDB & MySQL:

openSUSE has moved from MySQL to MariaDB as default. MariaDB was first shipped with openSUSE 11.3 back in 2010. Over the years it proved itself and starting with 12.3 openSUSE is replacing default MySQL implementation with MariaDB. This means that whole distribution is compiled against MariaDB and in ‘M’ in LAMP means MariaDB from now. As

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