Every once in a while, we hear of users with corruption in a file system that sits on top of DRBD. That may be easy or tricky to resolve. If you’re lucky, a simple fsck will resolve the corruption. If you’re not quite that lucky, you may have to get out your backups.

But that’s typically not DRBD’s fault. Typically not at all, not in the least bit. DRBD is a block device, and as such it has no idea what rests on top of it. It has no concept of a filesystem, let alone its integrity. That of course is true for any other block device as well. If you have, say, RAID-1, and something corrupts the file system on top of it, then of course that corruption will be happily replicated across both component devices. DRBD is no different, except that its component devices are stored across distinct physical nodes.

And even if everything about your filesystem is logically correct, there’s still the chance that a …

A live recording of my LinuxTag 2010 presentation entitled Storage Done Right: Building a Resilient, Distributed, Highly Available Open Source iSCSI SAN is now available from our web site. If you want to find out how to build a complete SAN from 100% open source, do take a look!

I do apologize for the less-than-optimal sound quality. I did the recording myself with my laptop mike, so unfortunately there’s quite a bit of clipping in the audio track. I hope my ramblings are still somewhat audible.

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Prologue: Long back there were golden days of post graduation in the “great” DDIT (Now Dharamsinh Desai University), Nadiad. Assignments, termwork and journals or everything similar was in demand – I attempted a java code as my termwork on Monday, October 03, 2005. [That’s created date of .java file, I don’t remember anything.] A “variable […]

While Yves presents a valid approach for managing NDB with Pacemaker and the anything Linux-HA resource agent (a generic wrapper for any daemon based application), the XML configuration shown is likely to have people running away screaming. This is how we had to do things back in the Heartbeat 2 days, which meant that as a cluster admin you would permanently run around with a loaded cocked shotgun with the muzzle pressed firmly against your foot.

Those days are long gone. Please don’t do this anymore. You also no longer need to use the low-level tools such as cibadmin or crm_attribute.

We have the crm shell …

I’m hearing a lot of “NoSQL” these days. To really understand how (and) does it works, I decided to give a try on MongoDB. MongoDB (hu*mongo*us) is an open source, scalable, high-performance, schema-free, document-oriented database written in the C++ programming language. MongoDB is not a Relational Database Management System. The database manages collections of JSON […]

This post covers the basic information of files that MySQL Server uses / creates for various tasks. Update: Various files in MySQL 8.0 Refer following updated article for latest information…

The post MySQL related file types and basic information first appeared on Change Is Inevitable.

Have you ever come across a situation called NO MORE SPOOL SPACE?  My friend does and hence I studied a bit about Teradata. The query: SELECT DISTINCT fieldname FROM tablename; The error: “NO MORE SPOOL SPACE”. Correct, the problem wasn’t related to MySQL, that was for something called Teradata. Initially, I could see that query should be […]

QA-Testing Definitions-Interview Questions: II (F – S): Data Dictionary: A database that contains definitions of all data items defined during analysis. Data Flow Diagram: A modeling notation that represents a functional decomposition of a system. Data Driven Testing: Testing in which the action of a test case is parameterized by externally defined data values, maintained […]

Are you tired of manually renaming MySQL tables, one by one, especially when dealing with a large number of them? In this guide, we’ll introduce you to a MySQL stored…

The post How to bulk rename table MySQL first appeared on Change Is Inevitable.

Yesterday a friend came across an oracle query problem: Consider below table: cid cname.... cdata 1 x xxxx 1 x xxxx .. 2 xzzz fjnd 3 a evddd Now the…

The post Oracle query-eliminate duplicate but one using rowid first appeared on Change Is Inevitable.