multiple sources, fragmentation and WHS

[crusader]

Hi,

Some time ago my SageTV system started stuttering (esp when playing HD). After some digging I've identified small cluster size (4kb) and extreme fragmentation to be the root cause. After spending few nights with Partition Magic, destroying half of my data I finally managed to resize clusters to 16kb, then decided to split disk into two partitions where one is dedicated completely for SageTV (and uses cluster size 64kb). Guys, my advice -- never use Partition Magic for cluster resizing -- this piece of sheet likes to fail in the middle of operation with mysterious errors (taking half of your files with it).
Anyways, now SageTV is happy and works fine. But I've noticed that recordings still end up being very fragmented due to the fact that when SageTV writes multiple recordings in parallel OS preallocates small chunks on-demand. So you end up with files being "interleaved" on the disk (i.e. 100kb of file1, then 100kb of file2, then again 100kb of file1, etc). Later when file1 is deleted and space is reused -- fragmentation goes on a rampage. In case if someone technical from SageTV team stumbles upon this posting -- what about doing preallocation manually (e.g. using 40Mb increments) using Win32 API function SetFilePointerEx(to move pointer forward) and SetEndOfFile(signals OS to preallocate space)? It works marvelously with overlapped I/O and FILE_FLAG_NO_BUFFERING (I am talking from my own experience). I am sure there are equivalents on Linux/etc.


How SageTV works with WHS? Does it write files to pool drive and OS later transfers it to another location? In this case this whole fragmentation problem do not exists, right? (fragmentation goes away during this "transfer to another drive" step)

Michael.

[sic0048]

Originally Posted by crusader

How SageTV works with WHS? Does it write files to pool drive and OS later transfers it to another location?

WHS doesn't really treat the files any differently than any other OS. The unique thing about WHS is how it backs up other computers. But if you use WHS to record shows, it will do so at whatever location you choose. It does not move them from that location.

Some people will put the hard drives they want to use for SageTV into the WHS drive pool. This way WHS can use that space for other functions like duplication and backing up other computers.

Personally, I leave the hard drives I'm using for SageTV out of the WHS storage pool. WHS simply sees these drives as normal, but "other" drives. I have them formated to 64k blocks and I only use them for Sage recordings.

You definitely need to format the drives you use for SageTV recordings to 64k block size. This is keep the fragmentation down to a minimum.