I'm going to answer these out of order.
- First compute the per recording bandwidth in bytes/second by taking the size of a file and dividing it by the number of minutes * 60. Here is an example (a 122 minute recording of "Finding Nemo".)
Code:
root@black2:/usr/local/bin# ls -l /myth/tv/1024_20060812125900.mpg
-rw-r--r-- 1 mythtv mythtv 6164161700 Aug 12 15:01 /myth/tv/1024_20060812125900.mpg
root@black2:/usr/local/bin# python
Python 2.3.5 (#2, Mar 26 2005, 17:32:32)
[GCC 3.3.5 (Debian 1:3.3.5-12)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 6164161700 / (122 * 60.)
842098.59289617487
-rw-r--r-- 1 mythtv mythtv 6164161700 Aug 12 15:01 /myth/tv/1024_20060812125900.mpg
root@black2:/usr/local/bin# python
Python 2.3.5 (#2, Mar 26 2005, 17:32:32)
[GCC 3.3.5 (Debian 1:3.3.5-12)] on linux2
Type "help", "copyright", "credits" or "license" for more information.
>>> 6164161700 / (122 * 60.)
842098.59289617487
- Next measure the HD performance using hdparm
Code:
root@black2:/usr/local/bin# hdparm -Tt /dev/hda
/dev/hda:
Timing cached reads: 3064 MB in 2.00 seconds = 1531.84 MB/sec
Timing buffered disk reads: 196 MB in 3.02 seconds = 64.95 MB/sec
/dev/hda:
Timing cached reads: 3064 MB in 2.00 seconds = 1531.84 MB/sec
Timing buffered disk reads: 196 MB in 3.02 seconds = 64.95 MB/sec
Even if you half that ~65Mb/s rate and figure 32Mb/s, you should still see about a 20x ratio. In other words, plenty of spare bandwidth
As for how to upgrade... You've already got all the tools you need. Check out the R5C7 upgrade hints thread here: http://mysettopbox.tv/phpBB2/viewtopic.php?t=10116 and the posting about the new backup and restore here: http://mysettopbox.tv/phpBB2/viewtopic.php?t=10117. They include detailed discussions of how to do exactly what you're asking.