64K Block partitioning?

[pjpjpjpj]

I installed SageTV on my PC this past weekend for the first time. I see that SageTV recommends partitioning your hard drive (that will store recordings) into 64K blocks. I am completely clueless about this.

I have an external USB 500G hard drive that will be used exclusively for storing recordings, both SD and HD. In anticipation of getting the system set up, I copied all my MP3s to this drive, to be shared through Sage. When I looked into formatting the 500G drive, it said "all data will be lost", so obviously I need to move the MP3s to another drive - at least temporarily (?) - so my question is, if I format this drive with the 64K block partitioning, is it still usable for other files besides the recorded TV shows? What does this exactly do to the drive? Would it effect the ability to store music, photos, etc., on the drive? Do I just need to move the MP3s elsewhere, reformat the drive, and then move them back?

In other words, what effect does "64K block formatting" have on things... and what problems would/might I see if I do not?

[jerryt]

Pro = 64K clusters increases drive read speed. Helps prevent stutter.
Con = Wastes a small amount of disk space, because every file smaller then 64K, will take 64K of space.

[cslatt]

jerryt is 100% correct - The advantage is in improving read speeds and decreasing disk fragmentation - helps keep your video playing smoothly. The downside is you waste a lot if space IF you have a lot of small files (smaller than 64K) on that drive.

[matt91]

And just to complete the loop on this question: MP3s are generally 3-10mb/ each, so you wouldn't be losing any space on these files. However, if you have lots of smaller coverart (or other small files), you'd be losing space.

There are some in-place formatting programs, I think. This has come up before, search around and you might fine a commercial recommendation.
Matt

[pjpjpjpj]

Thanks for the info - I agree, the MP3s wouldn't be the problem (and there wouldn't be any other files of mine on there), but I forgot about the cover art! That's a lot of wasted space. Of course, with a 500Gb drive, it might not matter, as the wife and I don't really let a lot of stuff pile up (our current Tivo is only a 35-Gig model and we have never come close... though granted it doesn't do HD).

If I move the MP3s to the PC's hard drive, they will take up about 75% of it (it's a small drive, hence the external one for TV), but will leave it at probably less than 10% free in total. My fear there is that the PC performance might suffer due to the hard drive being so full.

Could I pretty much count on stutter while watching recordings or "live" TV, if I do not format the drive with 64K blocks? Is it "frequent" or "rare"?

[gplasky]

Originally Posted by pjpjpjpj

Could I pretty much count on stutter while watching recordings or "live" TV, if I do not format the drive with 64K blocks? Is it "frequent" or "rare"?

Count on it.


Gerry

[Thomas Wischgol]

Originally Posted by matt91

And just to complete the loop on this question: MP3s are generally 3-10mb/ each, so you wouldn't be losing any space on these files. However, if you have lots of smaller coverart (or other small files), you'd be losing space.

There are some in-place formatting programs, I think. This has come up before, search around and you might fine a commercial recommendation.
Matt

Just to clarify: this is not really correct either. With any file that is n*64+1 kB in size you will loose 63kB as an example. Hence, chances are that you are loosing some disk space no matter how large the files. However, the ratio between used space and lost space becomes significantly better the larger the files. So if your files are a few GB in size (which TV recordings typically are) your space lost is minimal. For example, with recordings of 2GB each on a 500 GB hard drive you will have space for about 250 recordings. The maximal space lost is 63kB per file, hence 250 * 63kB = 15 MB. On the other hand with files of 10 MB each, you will be able to fit 50000 on the hard drive and therefore loose up to 3076 MB of space.

Thomas

[RobJ]

Originally Posted by Thomas Wischgol

Just to clarify: this is not really correct either. With any file that is n*64+1 kB in size you will loose 63kB as an example. Hence, chances are that you are loosing some disk space no matter how large the files. However, the ratio between used space and lost space becomes significantly better the larger the files. So if your files are a few GB in size (which TV recordings typically are) your space lost is minimal. For example, with recordings of 2GB each on a 500 GB hard drive you will have space for about 250 recordings. The maximal space lost is 63kB per file, hence 250 * 63kB = 15 MB. On the other hand with files of 10 MB each, you will be able to fit 50000 on the hard drive and therefore loose up to 3076 MB of space.

Thomas

Your post is completely and technically correct, but I would like to offer a counterpoint. It is generally customary to leave empty space, often 10 to 20 gigabytes, at the end of a drive, 'just in case' or because one's defragger demands it, or ... With so much unused space dwarfing the small amounts lost to less-efficient but better-performing clustering, arguments don't carry much wait to try to maximize space usage. They would only matter if you were running out of room.

[Opus4]

The cover art for albums won't take that much wasted space.

I just remembered that I have a utility to report disk space usage, taking cluster size into account to report wasted space, and reporting on the disk's current cluster size. This utility was more important when I had limited drive space & needed to make better use of the clusters, but since there seems to be a frequent question about how to check a drive's current cluster size, I've put it in the forum's download section: File Size & Disk Usage.

You can use it to see just how much those music files + cover art really use and how much space is wasted... and you'll probably see that the % wasted space is fairly low.

- Andy

[elaw]

Actually, estimating wasted space is pretty simple. The key is the "slack" (the industry term for space wasted due to partial cluster use), which averages 1/2 the cluster size*.

So you can get an approximation of wasted space by computing (cluster size / 2) * (total number of files on the disk or partition). So with 1000 files on a drive w/64K clusters, it's (64K/2 = 32K) * 1000 = about 32 megabytes. The same drive with 4K clusters (NTFS default) would have (4K/2 = 2K) * 1000 = 2 megabytes of wasted space. Neither number is very large compared to current HD sizes of 500, 750, 1000 gigabytes.

*This method assumes most of your files are much larger than the cluster size (usually the case on a HTPC). Doesn't work so well with small files, like on a web server with a bunch of .htm files that are only a few K each.

[GKusnick]

Originally Posted by elaw

So with 1000 files on a drive w/64K clusters, it's (64K/2 = 32K) * 1000 = about 32 megabytes.

To put it in perspective, that works out to about 20 seconds of HD video, maybe a minute of SD. Hardly worth worrying about.