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7200rpm vs 5400rpm drives

There seems to be a lot of people going with the 7200rpm drives because the performance is generally better.

The primary advantages of 7200rpm drives are access times, cache size and throughput.

Here are my theories:
When Tivo calls in, it goes through a "Housekeeping" mode. If you listen closely, the seeks are much more frequent during this process. I think this is equivalent to a defrag which puts the files in order contiguously, sector by sector.

When the data is ordered contiguously, the head seeks drop significantly and seek/access times are not as critical.

Cache is used to compensate mainly for access times and also throughput to a lesser degree. Again, the contiguous files make access times and cache size less critical.

Tivo records at about 6Mb/sec in best mode. Reading and writing in best mode you're at 12Mb/sec (or 1.5MB/sec) - significantly lower than the continuous throughput of any late generation drive, 5400rpm or 7200rpm.

I think the only area that would benefit from having a faster drive would be when the Tivo is doing something other than just playback and record ==> Housekeeping

There are 3 givens when comparing 7200rpm to 5400rpm drives:
More Heat - More Noise - Higher cost
(Note: always compare drives of the same generation ie. the latest gen 7200rpm drive will be cooler and quieter than a 5400rpm of several years ago)

*** Choose your B drive by capacity and price, not necessarily performance or manufacturer.

(From some of the posts, the A drives seem to be more particular and you may want to stay with an identical drive as the OEM if you choose to clone.)


What do you think???
Ray

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Sounds right to me. I only went with the Quantum LCT10 30G 4500RPM drive because that is what the 30hr units were using. I figure TiVo did the testing and those drives won out (or they got the best price on them). I have also had several Quantum Fireball HDs in my PC and have yet to have one fail, while a maxtor I had crashed on me.

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One other consideration with 5400 vs. 7200 rpm drives is heat. When you stir those air molecules faster you get more heat and 7200 drives are significantly warmer than their 5400 rpm counterparts. If the TiVo does not need the speed of the 7200 rpm drive I would stick to the 5400 just to help keep the temp down inside of the box.

------------------
Mike Schexnaydre

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Registered: Apr 1999
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Also, you should consider that 7200RPM drives often draw more current than 5400RPM drives. You do not want to overload TiVo's power supply.

/jab

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Registered: Oct 1999
Location: IL
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How much more current do they draw and what is the rating on the power supply?

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Registered: Apr 1999
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Current draw is usually available on the manufacturers' websites. You want to look at the spin-up draw rather than the idle or usage draw.

I don't know the rating on the TiVo power supply. Perhaps someone who already keeps their TiVo open can see if it's marked.

/jab

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