Filesystem Tuning Recommendations

Drew Tomlinson drew at
Mon Apr 25 08:09:41 PDT 2005

I'm attempting to build a FBSD 5.4 box running MythTV.  The box has a 
160 gb drive I want to use for nothing more than storing recorded 
shows.  Since the files are likely to be several gigabytes in size, what 
are some suggested tuning parameters for this file system.  I assume 
it's UFS2 (the default?) as I did nothing to change that.  I've read 
'man tunefs' and suspect the two options I should change are 'maximum 
blocks' and 'average filesize'.  So without really understanding the 
consequences, I changed them:

tv# tunefs -p /tv
tunefs: ACLs: (-a)                                         disabled
tunefs: MAC multilabel: (-l)                               disabled
tunefs: soft updates: (-n)                                 enabled
tunefs: maximum blocks per file in a cylinder group: (-e)  64000000
tunefs: average file size: (-f)                            512000000
tunefs: average number of files in a directory: (-s)       64
tunefs: minimum percentage of free space: (-m)             8%
tunefs: optimization preference: (-o)                      time
tunefs: volume label: (-L)

This seemed to help some because I used to get a "encoder dma not enough 
buffer space free" error on /dev/cxm0 and now that's gone away so I 
assume disk access is faster.  But what parameter would be optimum for 
my purpose?

Also there is some suggestion on the mythtv-users list that file sizes 
greater than 4 gb are not allowed.  What is the limit as far as FBSD 
UFS2 is concerned?

Thanks for your advice!


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