Tuesday, January 17, 2012

NTFS USN Journal and 3X backup

A problem I saw crop up a couple days with some of my customers using 3X Appliances is an issue where their USN journal fills up and causes their backup set to crash and burn. The good news with this is that there is actually a relatively easy fix that just requires the use of the fsutil utility from Microsoft.

Generally the USN journal max size is set fairly low, and this can be a problem depending on the number of files that exist in your file system. The journal's purpose is to add resiliency to the file system by providing a persistent log of changes being made to the file system. We generally suggest changing your journal max size to something along the lines of 512MB if you aren't tight for space. Generally for every 400,000 files you have you will want to add 128MB to the journal. The following technet article below discusses the command to change the journal in detail: http://technet.microsoft.com/en-us/library/cc788042%28WS.10%29.aspx. Making this adjustment will avoid problems our backup solution, as well as any others that make use of the journal.

This particular post is to remain rather short, however this week will have a second post to make up for it.

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