How to Avoid Heavy Fragmentation

[LewE]

I have a 500 GB drive I only use for recording programs. When I had a single Hauppauge tuner it would store programs with minimal fragmentation, e.g. maybe 4 fragments for a 6GB file. Even when I erased a program and subsequently recorded another the "holes" were large enough that newly recorded programs were not very fragmented.

I added a second tuner and now if the two tuners are recording simultaneously they each put small writes on the disk and the resulting files are heavily fragmented. I defragmented the disk. It had more than 200,00 excess fragments before the defreg. It took approximately 20 hours to complete. I then recorded some programs and the new programs are heavily fragmented, e.g. 7600 fragments for a 3.3GB file.

I understand this happens because of how Windows handles writes to disk. Is there a way you can have PVRX2, when it begins recording a program, reserve a large section of the disk based on the estimated storage requirements for the length of program being recorded and then do the writes as it records within this reserved space?

Because of the size of the recorded programs it isn't practical to frequently defragment the disk and if I don't defrag then the file segments are so small that it interferes with smooth playback.

This must be a common occurrence based on the number of people who identify that they have more than one tuner and presumably use them to record multiple programs simultaneoulsly.

[K.S.]

take a look here & here & here, that should take care of your problem

i don't think reserving space is a real option because:
1. it won't be trivial to implement (if at all possible by standard windows API?)
2. it would force the drive to many subsequent seeks during simultaneous recordings vs. fragment the drive but write both files on HDD without further hindrance (in performance & latency)
3. it might work against NCQ

[LewE]

Thanks for the quick response. That gives me a lot to look at.

[Anthony]

I use PerfectDisk and have it scheduled to defrag my hard drives between 3am and 6am. I tried several defragmenting programs, and PerfectDisk was the only one that would defrag my drive with a single run. I had to run the others multiple times to completely defrag the drive.

More importantly, PerfectDisk moves the oldest files to the start of the drive, which means only the remainder of the disk (i.e. the newest files) get fragmented.

Works great for me.

Anthony

[Koenie]

Maybe just one little remark. I use contig on a separate partition for the recording and it remains perfectly without fragments. I do start contig with low priority otherwise if several recordings finish around thus several instances of contig are running playback gets choppy:

start /low contig.exe %1

[martint123]

I've just installed a 750gb drive. I formatted it to 64kb block size rather than the default 4kb.
I'll see if it makes any difference - it ought to.

[wtg]

The best defrag I've seen, by a wide margin, is O&O Defrag from http://www.oo-software.com. I tested a whole bunch of them a long time ago and it's the only one that could completely defrag my drives at 1 go, even when they were near full. The difference was quite significant. It has lots of other configuration options, scheduling, etc. They also offer a trial.

I don't think I tried PerfectDisk. I'll check it out. My trial of O&O expired and I was just getting ready to purchase it. Good to have choices.

[philly_phenom]

I just use the windows defrag & added a task to defrag once a week - 2AM on a Saturday morning.

Come Friday, there's pretty heavy fragmentation, but I've never noticed it interfering with playback. If once per week is not enough, you can have it run two or three times - even daily if you want.

Yes there are better defrag tools out there, but I'd recommend trying this first since you don't have to purchase anything extra. If it doesn't meet your needs, then purchase another tool.

[LewE]

I use PerfectDisk and have it scheduled to defrag my hard drives between 3am and 6am. Anthony

I use Perfect Disk also (defragging my system disk every night and a second data drive I use for photos and videos I created once a week) but it takes a very long time to push around 500GB of multi-gigabyte files when it runs. Like I said, it takes around 20 hours to defrag the disk so defragging nightly is out of the question. I could run an Analyze and then defrag only the files that are heavily defragmented but I don't want to have to get involved in that manual process every day.

The CONTIG program may be the best solution for the extensive fragmenting that occurs when two or more tuners are recording simultaneously.

UPDATE: I sent a query to Raxco to see whether a scheduled defrag can be performed only on recently changed files. I expect the answer is "No" but in the past they have been receptive to adding features to the program.

One that I had requested before was the ability to select individual files to defrag by clicking on them from the "Most Fragmented Files" list after an analysis and this was added to Perfectdisk 2008.

[LewE]

I've just installed a 750gb drive. I formatted it to 64kb block size rather than the default 4kb.
I'll see if it makes any difference - it ought to.

When you are talking of program files being 3-6GB or more in size, I don't think the difference between 4KB and 64KB block size will make much difference.

Keep in mind that if you only have one tuner then fragmenting probably won't be an issue because when you delete a program you free up a contiguous space that can handle a similar length program. Before I added the second tuner fragmenting wasn't an issue at all. Even after multiple times of recording programs and deleting others I found that I would only get approximately 5-7 fragments for a newly recorded program. A 3GB file that is in 7 fragments will not impact performance at all.

It's only when you have multiple tuners writing to disk simultaneously and taking turns to write to the next available disk space that you get the problem.