Best allocation unit size for video and photos - AVS Forum
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post #1 of 8 Old 02-01-2010, 09:38 AM - Thread Starter
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So I just bought a new WD 1.5 TB 32mg cache caviar green hard drive and wondering what the best allocation unit size would be. I plan on storing a large amount of photos, as well as OTA DVR'd material. OS on a different drive. Different sources say different things. Is there a general consensus in the HTPC forums on this?
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post #2 of 8 Old 02-01-2010, 09:46 AM
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I use a 64K allocation size for all media storage. Speeds up data transfers(read/write) for large files, especially with large blu-ray rips.

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post #3 of 8 Old 02-01-2010, 10:29 AM
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I wouldn't use anything less than 64K for any drive that I expect to use to record/dvr TV shows. But that's just me.

Look at it a different way, let's say you have 10,000 files (movies and pictures) on your media drive (possibly somewhat high of a number for the average person, but I have at least twice that many on my photo drive.) Now to make the math easy, let's say you choose between 4KB clusters and 64KB clusters. To further simplify, let's say that each file you load on there was sized just so that 4KB clusters would result in completely optimized filling of the HDD and yet the files would always waste the left over 60KB of space in a 64KB cluster (this wouldn't happen as most of the time a file would leave even some of the 4KB cluster wasted and it would also fill more of the 64KB cluster too.)

Now, assuming 60KB wasted for *each* file in this worse case comparison, you will be losing all of 600MB if you picked 64KB instead of 4KB.

If 600MB of storage lost is too much for you, then pick a smaller block size.

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post #4 of 8 Old 02-01-2010, 12:34 PM - Thread Starter
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Thanks for the info guys....When using the larger allocation sizes, does that reduce the chances of lag and/or stutter with video playback, or are there also other benefits that I haven't thought of?
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post #5 of 8 Old 02-01-2010, 12:50 PM
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Quote:
Originally Posted by Tucdaddy View Post

Thanks for the info guys....When using the larger allocation sizes, does that reduce the chances of lag and/or stutter with video playback, or are there also other benefits that I haven't thought of?

Yes. Although it is less of an issue if you are only recording one stream at a time. If you are recording multiple streams, and/or playing back a video off the disc while recording a stream, you can suffer in that case too.

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post #6 of 8 Old 02-01-2010, 01:04 PM - Thread Starter
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Thanks Suntan...yea I mostly plan on using my PC to record OTA digital, just hooked my my HD homerun today, as well as the aformentioned HD. My video card is still in the mail, but it plays pretty well using the built in graphics chip ( 4300 intel core 2 1.8 ghz), with occasional stutter if I'm doing something in the background. I'm hoping the video card (saphirre 4550 512mg RAM) will help out. I'm very excited to be ditching cable. I think I'll take your advice and go with the 64K....Thanks again
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post #7 of 8 Old 11-29-2010, 05:23 PM
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Fascinating thread. Sorry for bumping an old thread, but there are so many things that can be discussed about allocation sizes...
Quote:
Originally Posted by Suntan View Post
I wouldn't use anything less than 64K for any drive that I expect to use to record/dvr TV shows. But that's just me.

Look at it a different way, let's say you have 10,000 files (movies and pictures) on your media drive (possibly somewhat high of a number for the average person, but I have at least twice that many on my photo drive.) Now to make the math easy, let's say you choose between 4KB clusters and 64KB clusters. To further simplify, let's say that each file you load on there was sized just so that 4KB clusters would result in completely optimized filling of the HDD and yet the files would always waste the left over 60KB of space in a 64KB cluster (this wouldn't happen as most of the time a file would leave even some of the 4KB cluster wasted and it would also fill more of the 64KB cluster too.)

Now, assuming 60KB wasted for *each* file in this worse case comparison, you will be losing all of 600MB if you picked 64KB instead of 4KB.

If 600MB of storage lost is too much for you, then pick a smaller block size.

-Suntan
Very interesting. What would you say is the cut-off size or the least you would recommend for the highest allocation formats? For example, if the least someone has is a 10mb file, or for video files, say a 250MB file, would the 64kb cluster be the best choice? If so, this is the case for a large amount of files, really - I wouldn't even consider using an external hard drive for small documents and such. I'm currently trying out various allocation size structures; right now, I'm doing a full format of a EHD (with a 16kb cluster to start off with), then after it's done experiment with a quick format for the 32kb and 64kb clusters. Any input on this would be highly appreciated.
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post #8 of 8 Old 11-30-2010, 08:06 AM
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I really haven't taken the time it test for the optimum. The way I set it up is that I leave the OS drive at the default size. (Windows has a bat-sh!t heavy load of tiny little files.)

My drives for disc rips, digital photos, HD home videos, and DVRed TV shows all get formatted at 64K size.

My main backup drive, which is used for prompt backups of photos & home videos, as well a general catch all for downloaded programs, updates, etc.; I format at 32K. The external USB HDDs that are used less often for offline backup are formatted at the default size.

I'll normally defrag the OS drive right after a fresh install of the OS and all programs, but otherwise I don't really defrag anything.

The only time I've seen large cluster sizes make a definite difference (the difference between working and not working) is with DVRing multiple HD tuners. But the little bit faster advantage is a plus with ripping as well as general photo editing, imo. The Gig or so of space lost (absolute worst case) in my setup is worth it to me.

-Suntan
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