What is a Volume Snapshot?

Posted by R1Soft on Nov 30, 2009 8:13:00 AM

Following up with my last post about why the CDP MySQL Add-On is so important to getting a good backup of your MySQL database I have been asked a lot: “What good is the point-in-time snapshot anyways if it’s not good enough for MySQL? What about XYZ application?”

Beauty of the Snapshot is in the Eye of the Beholder

I think it’s hard to talk about volume snapshots without talking about who you are and what applications you use.  If you are a database admin you have one view, a Linux server admin a different view, and a Windows server admin yet a third view.

Windows Server Admins

You know you need some way to get a backup copy of open files as Windows enforces file locking and windows application typically lock files for reading.  When you shop for backup software you are used to making sure it has some kind of support for backing up open files.  Before MS Volume Shadow Copy you may have purchased expensive third party tools like OTM (open transaction manager) to solve this problem with your backups in the past.

Linux Server Admins

You probably never thought much about snapshots or consistency of files during backup.  On Linux the root user can read any file it wants and at any time regardless if the file is being written to or not.  You can even read locked files. Basically you are not protected from yourself unlike Windows where file locking really locks files. 

Database Administrators

You know your database needs more than just a file copy when it comes to backup.  You perform a scheduled database dump at a minimum, you likely purchase add-ons from your Windows/Linux file backup vendor that supports your database (e.g. R1Soft).  You may even purchase a specialized commercial database backup tool made just for your database.

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Topics: ext4, Continuous Data Protection, windows, mysql, linux, NTFS, file systems, ext3

The Fine Print on File System Journaling

Posted by R1Soft on Oct 13, 2009 2:27:00 PM

This is part 1 of a three part post:  Part 2, Part 3.

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Topics: ext4, windows, linux, file systems, ext3

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