[mythtv-users] Changing filesystems?

[William Powers]

My last reply to myself.  Based on a Googled reference, I was able to 
break my XFS 4G file size barrier by formatting the partition 'mkfs.xfs 
-dagsize=4g'.  So, here are the complete results:

Time to delete a 10G file, fastest to slowest:

JFS:                 0.9s, 0.9s
XFS:                 1.3s
EXT3:                1.4s, 2.3s
EXT2:                1.6s
REISERFS:            6.2s
EXT3 -T largefile4:  5.9s, 10.2s

After running the XFS test, there didn't seem to be any point in 
reformatting the partition again, so I left it on XFS, but I think I 
would be happy with JFS, XFS, or EXT3 w/o '-T largefile4'.

Bill

William Powers wrote:
> Ok, now I'm replying to myself...
> 
> The mkfs.ext3 problem was caused by some peculiarity in the partition 
> table.  Deleting and recreating the partition fixed it.  It did not, 
> unfortunately, fix my XFS 4G problem...
> 
> With the mkfs.ext3 problem fixed, I was able to confirm that it does 
> take longer to delete a file on an ext3 filesystem when that filesystem 
> was formatted -T largefile4.  Two instances of deleting a 10G file on a 
> filesystem formatted 'mkfs.ext3 -m 0' resulted in times of 1.4 and 2.3 
> seconds.  Two attempts at deleting a 10G file on a filesystem formatted 
>  'mkfs.ext3 -T largefile4 -m 0' took 5.9 and 10.2 seconds.
> 
>  From this I would personally conclude that, if you want to use ext3 for 
> your video partition, the extra storage space I get by formatting '-T 
> largefile4' (about 2G more available space on a 100G partition) is not 
> worth the substantial decrease in file deletion performance.
> 
> Now, if I could just figure out my XFS problem...
> 
> Bill
> 
> William Powers wrote:
> 
>>  >> Based on that, I ran an experiment to compare the deletion time of a
>>  >> single 10G file on an ext3 partition and on a JFS partition. The
>>  >> results were 10.2 seconds to delete the file on the ext3 partition
>>  >> and 0.9 seconds to delete the file on the JFS partition.
>>
>>  > You didn't by any chance do the same test with ReiserFS did you?
>>
>> I did not test anything except JFS and Ext3 the first time around,  
>> but I have since tried to do a slightly more comprehensive test by 
>> attempting the single 10G file delete test for all five of the 
>> relevant file systems.  However, I had some issues and wasn't able to 
>> complete the full test as I had planned, this on an RHFC1 system with 
>> the Myth components installed via ATRpm's.
>>
>> JFS:  Repeated the 10G file delete and got 0.9 seconds again
>>
>> ReiserFS:  Got 6.2 seconds for the 10G file delete
>>
>> Ext2:  Got 1.6 seconds for the 10G file delete
>>
>> Ext3:  For some unknown reason, I was not able to (re)format the 
>> partition using 'mkfs.ext3 -T largefile4 -m 0 /dev/hdb4' as it was 
>> originally without encountering a floating point exception.  After 
>> formatting the partition using 'mkfs.ext3 -m 0 /dev/hdb4', I repeated 
>> the 10G file delete and got 2.3 seconds.  At this point, I have no 
>> idea why I was unable to use '-T largefile4', nor do I know whether 
>> the apparent difference in times between partitions formatted with and 
>> without 'largefile4' is significant.
>>
>> XFS:  For some reason, attempting to write a 10G file to the XFS 
>> formatted partition locked up the PC (hard) at about the 4G point, 
>> each and every time.  So I am unable to perform the 10G delete test 
>> with XFS unless and until I find out what my 4G problem is.
>>
>> So, that is where things stand at the moment...
>>
>> Bill
>>
>>
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