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Discussion in 'TiVo Coffee House - TiVo Discussion' started by MojoB, Jul 20, 2012.
Okay, what was the point of it on S1s and S2s?
They were ahead of their time.
One reason is for people who had(have?) the cable daisy chained to the TV.
Personally, I really liked this, though I admit I don't think I used it on the Tivo.. I used a
similar capability on one of my VCRs. You could turn off the VCR's output on coax, so simply have the cable plugged into the VCR then plugged into the TV. You weren't (necessarily) using coax from the VCR to the TV to watch on the TV (of course then you only get mono audio), but you could use the TV's tuner to watch something else while recording, for example.
Even if they were 'just' internal splitters (which I guess is what the VCR did), it tremendously reduced cable clutter.. and I should know, with a zillion things hooked up to one TV.. (though I purposely have more clutter than I "need", since I essentially use my Toshiba XS32 as the "video switcher" the vast majority of the time, and use the TV's other inputs only sometimes..)
Does anyone know about my other question - When you press rewind/pause/fast forward continuously and let it rewind/fast forward through 5-10 minutes or stay paused for 5-10 minutes is it only accessing different data from the RAM or is the hard drive spinning to different areas?
Well, first of all, almost no data from the video is kept in RAM. Only enough is buffered to allow for smooth playback given the somewhat uneven nature of I/O on a computer. I don't know how much precisely, but it is quite possible it is less than 1 second worth of data. Of course, some is also buffered on the hard drive. Some modern hard drives have as much cache memory on them as some TiVos have in total. Indeed, there are a few SSD cached hard drives that have considerably more. As I pointed out above, one minute of recorded 1080i data on a TiVo HD requires nearly twice as much RAM space as the THD has installed.
Secondly, you seem to have a bit of an odd idea of how a hard drive works. The drive does not "spin to different areas". As long as the drive has power and is not in sleep mode, the motor spins the platter spindle at a constant rate. Typical rates these days are 5400 RPM, 72000 RPM, or 10,000 RPM, depending on the drive. The higher the spindle speed, the faster, generally speaking, data can be read and written on the drive. Most hard drives have more than one recording surface (or platter). Each platter has its own read-write head floating over its surface as the platter spins, but all the heads are part of a single servo arm that moves the heads in unison back and forth across the drive surfaces. Looking at it geometrically, a specific registered position of the servo arm defines a ring, or "track" on the platter surface. A specific set of tracks all put together can be thought to form a cylinder of a specific radius intersecting all the platters. Each track is divided up into a specific number of sectors and each sector is given a number. Each individual sector on the drive, then, can be specified by giving its cylinder number, head number, and sector number. When a seek command is issued, the drive checks to see where its servo arm is located. If the servo arm is not on the requested cylinder, then it is moved until the heads are all hovering over the surface at the requested cylinder. As each sector then passes underneath the heads, the drive takes notice of the passing sectors until the requested one passes underneath the heads, at which time the drive begins reading from or writing to the requested sectors. Typically this will continue on one read/write head until the last sector of the track is reached, at which point the next head takes over the read or write operation, until either the last sector of the cylinder has been addressed or all the requested data has been handled. Subsequent seeks will cause the servo arm to jump back and forth across the platters, servicing each request.
At this point one should note a few items:
1. Reading and writing do not affect the spindle motor or its bearings. Whether the drive is continuously reading and writing or never reading or writing at all, the stress on the drive motor and bearings is essentially constant.
2. The servo arm is very light in mass. There is no reason for it to have a lot of mass, and indeed the smaller its mass, the faster it can move across the platters, reducing seek time. Consequently, the stress on the arm mechanics and its bearings is rather small. In short, it is a very durable mechanism under normal operating conditions, even under high data loads.
3. While the servo arm has the ability to swing wildly back and forth across the platters from the very first to the very last cylinder at high speed, during normal data operations - especially video reads and writes - the actual size of the excursions is generally much more limited. More often than not, any given seek is usually to an adjacent cylinder or at least to a cylinder close by. This has the effect of reducing the actual stresses on the servo arm mechanism to well below the maximum possible operational stress. Try listening to a hard drive under normal video read / write activity and then try running a random seek benchmark some time to see what I mean.
Edit to add that if lrhorer's post had landed in time for me to see it before submitting mine, I wouldn't have bothered with this one.
The hard drive always spins in the same place, but the head assembly seeks at different spots on the platter stack, depending on what it's sent to get, and I suspect there's not enough RAM on the mobo to hold very much video at all so I expect almost everything is being fetched from the drive and put into the RAM that serves the Digital to Analog converters that feed the video and audio outputs.
Why? What purpose would it serve?
It would allow people to pay tribute to the pagan god of token environmentalism.
It would save a significant amount of power for the ~18-19 hours a day (more on weekends) that it's not _actively_ recording something for me or I'm not watching it (it recording something for me and me watching it are mostly aligned, at least on weekdays.. even though of course I'm watching something PREVIOUSLY recorded to skip ads).
+1. Even if each Tivo can only save a few watts a day, with millions of Tivos that is still a huge number. I would like to see Tivo Inc become more environmental friendly and put Tivo to "sleep" when not in use in order to save energy.
As far as DVRs that spin down when not being used, Polaroid,Panasonic, Toshiba(non tivo), and others all spin down, but I have no evidence that they last longer, as I never used them long enough.
On the old S1 and S2 DTiVos Standby actually would stop the buffering.
But oddly wouldn't empty the buffer.
So if you put it in standby for 30 minutes, then woke it up and paused it for 15 minutes you'd could have a buffer with the first and last 15 minutes of an hour long show, seperated by a bit of a visual glitch. (no discontinuity in the green buffer bar; nothing to indicate that there was a gap in the recording from standby)
It was a little bizzare
There is no such thing as "watts a day". It is just "watts", a measure of energy used (in Joules) per second. Watt-hours per day would also be a valid measure of power, albeit a rather goofy one. Spinning down the hard drive when not recording will save perhaps 10 watts, or about $6 - $7 a year in energy. By comparison, my air conditioners in my house cost well over $5000 a year to run.
Try turning it off.
That's what I meant, worded incorrectly, when I said the hard drive spin to different areas I meant the head thing. I was just wondering if I'm putting significant "wear and tear" on my hard drives whether it be tivo, computer, etc by constantly pausing/rewinding/fast forwarding. I generally pause/ff/rewind every couple minutes while watching programs, maybe 20-30 times per hour.
I thought it might prolong it's life, if not the hard drive, then at least the power supply.
I'm still using the Tivo and turning it on and off all the time would put even more wear and tear on the Tivo, and especially because that requires actually unplugging it.
The TiVo is designed to be plugged in and left that way.
Plug it in and leave it that way.
There's not much in the way of consumer electronics these days that's designed to have power completely disconnected, rather than being put into some sort of low power comsumption standby.
It's been some time since the power button on a computer actually disconnected and reconnected the AC line from the power supply (although anyone who manufactures an ATX supply without a switch on the supply itself should be horse whipped and count themselves lucky not to have been taken out and shot).
Having electricity applied when an instant ago it wasn't there is generally harder on electronics than being left on, and the more power cycles the sooner the item is likely to break down.
There are hard drives that have been running for years because they've been kept running instead of being started and stopped.
What's the economic and ecological comparison between using extra electricity on the one hand and on the other hand replacing equipment more often, and filling landfills more often, and using more conflict minerals? Beats me.
I expect not.
Unless the device has something like the filament in an incandescent bulb, by a wide margin most devices will last longer if submitted to constant loads well within the limnits of their design parameters. Starting and stopping devices tends to be rather hard on them.
Continuous normal use will more than likely obtain the greatest longevity for the unit. That doesn't guarantee it won't fail inside of 10 days, but such failure is probably not hastened by continuous use.
When a item first is connected to power the most strain takes place because the most current flows to get everything going. After that only a small trickle of current flows. Add to the fact that usually that happens when the power returns after a power outage, so everything else is coming up and causing the voltage to sag. That is why it is best to have all your equipment on a battery back up that not only gets things running for at least awhile, but also the batteries protect the devices by absorbing surges. . And if not that, then unplug everything until the power returns for good and then replug everything in.
It is good to have everything at least on a surge protector if nothing else, as most surge protector manufactures guarantee to replace items that are damaged if the protector doesn't work.
I've always unplugged all my electrical devices whenever there is a thunderstorm or very bad weather. I do have them on surge protectors but I don't know how many surges those protectors have gone through and how good they are anymore. And someone in my house loves to bring home surge protectors they find regardless of if they've been used and for how long. Those battery backup things are way too expensive and they never seem to stay very good, battery usually dies out too quickly. Although I unplug everything, I usually ignore the tv cables though.