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Discussion Starter · #1 ·
I came across this tutorial on using a usb stick as a live recording buffer in Win7 MCE.

http://www.hack7mc.com/2009/07/using...tv-buffer.html


does it have any advantages (besides speed)? would it save my hard drive from constant writes when live tv is on, possibly extending the life and cutting power consumption?


also how much speed would it actually give, since its pretty responsive to begin with...


seems like a cheap upgrade if its worth it...
 

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Quote:
Originally Posted by mike_311 /forum/post/16921001


does it have any advantages (besides speed)? would it save my hard drive from constant writes when live tv is on, possibly extending the life and cutting power consumption?

It would cut power consumption by a tiny bit, but it would actually be significantly slower and less reliable than a hard drive.


Think about it - the USB bus is limited to 480Mb/s, while a SATA 3.0 bus flies along at 3Gb/s. Of course neither gets that fast in the real world, but your system can still write to the HD several times faster than a USB drive. Solid state flash memory also has a limited number of write cycles before it fails. It's a high number (at least a couple hundred thousand), but it's still limited. Hard drives, on the other hand, can write to the same bit on the platter an effectively unlimited number of times. Heavy use does reduce the lifespan of the drive in general, but only slightly. No one spot on the platter is going to "wear out" from over-use.
 

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Quote:
Originally Posted by candre23 /forum/post/16923517


It would cut power consumption by a tiny bit, but it would actually be significantly slower and less reliable than a hard drive.


Think about it - the USB bus is limited to 480Mb/s, while a SATA 3.0 bus flies along at 3Gb/s. Of course neither gets that fast in the real world, but your system can still write to the HD several times faster than a USB drive.

That's true, however it's not just write speed but also read speed and, more importantly for Live TV, random access speed that matters. In sustained Read speed they're probably close, but in random access speed the USB memory stick will blast the harddrive out of the water.


Quote:
Originally Posted by candre23 /forum/post/16923517


Solid state flash memory also has a limited number of write cycles before it fails. It's a high number (at least a couple hundred thousand), but it's still limited. Hard drives, on the other hand, can write to the same bit on the platter an effectively unlimited number of times. Heavy use does reduce the lifespan of the drive in general, but only slightly. No one spot on the platter is going to "wear out" from over-use.

With wear leveling the chances of a memory stick wearing out are roughly even with a harddrive wearing out given reasonable usage. Even then, if it takes 100,000 writes to wear out a USB stick, and a stick can hold 30 minutes of live TV, you'de have to watch Live TV for 5 years straight to reach 100,000 writes. And note that all USB sticks, just like harddrives, have built in mechanisms to recognize bad clusters and write around them.


If you're going to be jumping all over the place in the video stream it may make sense to use a USB flash stick; however for most uses I can't see any real advantages over using the harddrive. You'd be better off setting up a RAMDrive if you're that worried about speed.
 

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Quote:
Originally Posted by ericbsmith /forum/post/16923884


That's true, however it's not just write speed but also read speed and, more importantly for Live TV, random access speed that matters. In sustained Read speed they're probably close, but in random access speed the USB memory stick will blast the harddrive out of the water.

Hardly. Sure, the latency of the NAND itself may be low, but factoring in the latency of the cheap-o controllers in most USB sticks and the latency of the USB bus itself, and you're well over the 15ms or so that your hard drive would take. Your computer would have to be doing a lot of other stuff with your hard drive to bog it down below USB flash drive speeds.
 

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Quote:
Originally Posted by candre23 /forum/post/16923970


Hardly. Sure, the latency of the NAND itself may be low, but factoring in the latency of the cheap-o controllers in most USB sticks and the latency of the USB bus itself, and you're well over the 15ms or so that your hard drive would take.

Uhh, yeah, you ever actually tested that or are you just making stuff up? 'cause I have tested it, and I have to say you probably haven't so I gotta assume you're making stuff up. In random access speed a decent, cheap, USB stick can hit 0.5ms or faster, which is the one area where USB Flash drives just blows harddrives away.


Not that latency/random access speed really means that much when you're talking about reading multi-MB of data (as in a live TV stream) - it'll start playing 1/10th of a second sooner when you FF/Rew is about all. Burst speed and read speed are going to be close to or slower than a harddrive, and write speed will be horrible, which is the real bottleneck. As I said, unless you're going to be jumping all over the place in the video stream it isn't going to help ya.
 

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Discussion Starter · #8 ·
thanks for the info, i dont really watch that much tv, so i wasnt sure if the small price of the usb stick would be worth he setup or not, and apparently it really isnt.
 

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Quote:
Originally Posted by mike_311 /forum/post/16925022


thanks for the info, i dont really watch that much tv, so i wasnt sure if the small price of the usb stick would be worth he setup or not, and apparently it really isnt.

Actually, this isn't such a bad idea. If you're using it for liveTV you're really only going to have one active stream at any given point in time. That's ~ 19Mbps that's bits not bytes means you should only need ~2.5MB/s. A decent USB flash drive can do upwards of 20 MB/s, it should be able to handle it. This would save the main drive of the constant buffering. It would be worth trying if you watch a fair amount of live TV. Could also be useful for FF or other browser temporary files.


Mike
 
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