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Showing entries 1 to 10 of 1147 10 Older Entries

Displaying posts with tag: Linux (reset)

XFS and EXT4 Testing Redux
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In my concluded testing post, I declared EXT4 my winner vs XFS for my scenario. My coworker, @keyurdg, was unwilling to let XFS lose out and made a few observations:

  • XFS wasn’t *really* being formatted optimally for the RAID stripe size
  • XFS wasn’t being mounted with the inode64 option which means that all of the inodes are kept in the first 2TB. (Side note: inode64 option is default in newer kernels but not on CentOS 6’s 2.6.32)
  • Single threaded testing isn’t entirely accurate
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More EXT4 vs XFS IO Testing
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Following my previous post, I got some excellent feedback in the forms of comments, tweets and other chat. In no particular order:

  • Commenter Tibi noted that ensuring I’m mounting with noatime, nodiratime and nobarrier should all improve performance.
  • Commenter benbradley pointed out a missing flag on some of my sysbench tests which will necessitate re-testing.
  • Former co-worker @preston4tw suggests looking at different IO schedulers. For all tests past, I used deadline which seems to be best, but re-testing with noop could be useful.
  • Fellow DBA @kormoc encouraged me to try many smaller partitions to limit the number of concurrent fsyncs.

There

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IO, IO, It’s Off to Testing We Go
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In my last post, I learned in disappointing fashion that sometimes you need to start small and work your way up, rather than trying to put together a finished product. This go-round, I’ll talk about my investigation into disk IO.

In an effort to better understand the hardware I have and it’s capacities, I started off by just trying to get some basic info about the RAID controller and the disks. This hardware in particular is a Supermicro, with a yet unknown RAID controller and 16 4TB disks arranged in RAID 6. Finding out more disk and controller information was the first step. “hdparm -i” wasn’t able to give me much, nor was “cat /sys/class/block/sdb/device/{model,vendor}”.

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Even If You Fail, You Can Still Learn
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As many learning experiences do, this one also starts out “So I was working on a project at work and…”.  In this case, the end result is to try to run as many concurrent copies of MySQL on a single server as possible, maintaining real time replication each running differing data sets. To help with this, I sent out to do this on a server with 36 7200rpm 4GB SATA disks, giving me roughly 120TB of available space to work with.

This isn’t an abnormal type of machine for us. Sometimes you simply need a ton of disk space. There is a quirk with this particular machine that I’ve been told: the RAID controller has some issues with addressing very large virtual disks and I should create 2 60TB volumes and stitch them together with LVM. Easy enough: pvcreate both

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How to start Percona Xtradb Cluster on CentOS 7
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Normally, when we want to start PXC (Percona XtraDB Cluster) on RHEL/CentOS 6 or older then that, we can simply start with init.d script or service command. i.e shell> /etc/init.d/mysql start OR shell> /etc/init.d/mysql bootstrap-pxc shell> service mysql start. But, Continue reading →   [Read more...]
Is automation killing old-school operations?
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Join 27,000 others and follow Sean Hull on twitter @hullsean. I was shocked to find this article on ReadWrite: The Truth About DevOps: IT Isn’t Dead; It’s not even Dying. Wait a second, do people really think this? Truth is I have heard whispers of this before. I was at a meetup recently where the […]
linux swap and mysql memory
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After mysql installation, To make mysql server production ready we have to tune default mysql variables considering the hardware, production load, performance, durability etc.

But What about the optimizing  Linux OS settings  with mysql ?

Here it is, i encountered  an issue once when i was checking TOP output for mysqld process and found that the mysqld  memory continuously increasing. Also there was one more thing  that it was using swap memory even if there was enough RAM memory available. we have monitored for a week and this was causing an issue like slow query processing, performance and slowness on DB server.

To solve this problem we have to set correct swappiness

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How to install sysbench 0.5 on Debian 7
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Normally, sysbench 0.4.12 version can be installed from repositories like “apt-get install sysbench” but the newer version 0.5 is not added in any repo yet (AFAIK) so, it’s bit difficult to install it. 1. Install bzr package if it’s not Continue reading →   [Read more...]
How to use and get output arguments in stored procedure using OUT parameter mode?
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It is sometimes required to get the result of a stored procedure in a variable which can be used later or to output the result.

To do so, we can use the "OUT" parameter mode while defining stored procedures.

In the below section, we will be writing a stored procedure to get the square root of a number returned in an output variable provided by us.



Stored Procedure Definition:

Store the below stored procedure in a file named my_sqrt.sql and save it.

DELIMITER $$

DROP PROCEDURE IF EXISTS my_sqrt$$

CREATE PROCEDURE















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libssl.so.6: cannot open shared object file with Debian/CentOS
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Actually, I found this error many times, while installing MySQL/Percona servers with MySQL Sandbox. To resolve this issue, first, you have to make sure that, SSL is installed /update properly. sudo apt-get update sudo apt-get install libssl1.0.0 libssl-dev After installing Continue reading →   [Read more...]
Showing entries 1 to 10 of 1147 10 Older Entries

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