# FEATURE REQUEST: Power-off hard drive



## keitheva (Aug 23, 2002)

The 921 hard drive just keeps on spinning even when the unit is powered-off:

a) it's noisy,

b) this prematurely wears out the drive.

Please spin-down the drive on 921 power-off (just like the other Dish DVRs).

Thanks,
-Keith


----------



## Jacob S (Apr 14, 2002)

I know that they implemented a hard drive shutdown feature on the DVR's via software download after four hours of inactivity when it is powered on. I do not know how this affects it with the power turned off.


----------



## keitheva (Aug 23, 2002)

Jacob S said:


> I know that they implemented a hard drive shutdown feature on the DVR's via software download after four hours of inactivity when it is powered on. I do not know how this affects it with the power turned off.


Not on the 921 apparently. Left the 921 powered-on overnight and the drive was still whirring merrily away this morning. So it makes no difference whether powered-on or off - the drive keeps spinning.


----------



## DonLandis (Dec 17, 2003)

This is just a thought and I have no tech info that it is how it really works. Mark maybe you could ask. On a Tech Chat last summer, it was describbed that E* believes the PVR's should be powered off when not in use. Later my own source alluded to the buffer as being what is allowed to rest during Power button off, plugged in mode.

Hard drives actually have two mechanical finctions that are a source for aging. The first is a spinning set of disks. The second is the I/O pickup arm that swings rapidly back and forth over the disk much like the tone arm of a record player only back and forth thousands of times faster, constantly when data I/O is requested.
In the case of the 921, the data I/O is on constantly while the DVR is turned on and plugged in. It is recording constantly a 2 hour buffer on the last active tuner channel.

I believe that while power buttoned Off, the PVR921 ceases buffer record activity giving the hard drive a rest period for the swinging pickup arm only. However, the drive's spinning disks continue at rated speed. I also believe that the act of a rotating disk is a much less mechanically taxing than the swinging pickup arm. MTBF is based on intermittant I/O activity on hard disks along with constant spinning in a normal computer application. The PVR is not intermittant but constant, due to the buffer record. By allowing the drive to rest daily in the mechanical activity that is outside the MTBF testing, I feel the failure rate can be effectively reduced. E* may discover a need to spin down the drive after collecting data on PVR failure rates but at this time, understanding that switching off the buffer record for a rest period is the next best thing to preserve the life of the drive.


----------



## Mark Lamutt (Mar 24, 2002)

I've sent off a message to Eldon to get a clarification on this.


----------



## keitheva (Aug 23, 2002)

DonLandis said:


> This is just a thought and I have no tech info that it is how it really works. Mark maybe you could ask. On a Tech Chat last summer, it was describbed that E* believes the PVR's should be powered off when not in use. Later my own source alluded to the buffer as being what is allowed to rest during Power button off, plugged in mode.
> 
> Hard drives actually have two mechanical finctions that are a source for aging. The first is a spinning set of disks. The second is the I/O pickup arm that swings rapidly back and forth over the disk much like the tone arm of a record player only back and forth thousands of times faster, constantly when data I/O is requested.
> In the case of the 921, the data I/O is on constantly while the DVR is turned on and plugged in. It is recording constantly a 2 hour buffer on the last active tuner channel.
> ...


Maybe. But when powered-off my DVR508 spins down the hard-drive completely. I believe other Dish DVRs do so as well. So the 921 is an anomaly in this regard.

And in any case, I would still like the option to spin down the drive on power-off because it's noisy.


----------



## Jacob S (Apr 14, 2002)

I have heard my 721's hard drive still spin after it was shut off, and quite a bit as well without any recordings happening. Perhaps it does that from time to time to update EPG information. How long does a hard drive last if it were to be on continuously?


----------



## DonLandis (Dec 17, 2003)

_"MTBF is a product of a large quantity of drives (numbering in the hundreds or low thousands, perhaps) and the number of hours that such a batch runs before experiencing a failure. If a manufacturer places 1000 units to the test and on average manages to squeeze 50 days of operation out of the batch between each individual unit failure, that firm's product has achieved an MTBF of at least 1.2 million hours. "_

Pulled this off an FAQ from a HD mfg.


----------



## Slordak (Dec 17, 2003)

Bear in mind that there are two types of mechanical operations which the drive is performing:

1) Rotating the spindle (i.e. spinning the drive).
2) Moving the arm (i.e. moving the heads).

When a PVR/DVR is on, it is effectively causing both of these types of mechanical operations, since it is constantly recording the satellite stream to the disk. When the unit is turned off (and no timers are actively recording), stream recording activity generally ceases (unless the unit has the capability to "rewind live TV even if the unit was previously off"), and hence the arm stops moving. This does reduce wear and tear on the drive.

It is also possible to ask the drive to "spin down", where it either stops spinning altogether or spins at a slower rate, and the arm moves to a safe "rest area". The drive cannot actively be used in this state, but this mode reduces power consumption and can reduce wear and tear on the drive as well. When the drive needs to be activated again, it takes a few moments to spin back up to speed before it can be used again (to read and write data).

It may be beneficial to the life of the drive to implement this low power "spin down" of the drive on the 921, but it depends somewhat on how this is done. If the spindle completely stops rotating and has to be brought back up to speed, this can actually *add* wear and tear due to this operation. Remember that many electric / electronic devices actually are most likely to experience a failure during power up or power down (compared to when they are running "steady state"), so constantly fully spinning up and fully spinning down can actually cause early mortality.


----------



## CAL7 (Dec 16, 2003)

Are you sure the HDD is spinning? I can't hear mine because the fan is so loud. The fan definitely is constantly on. But, when not in use, I can feel a definite decrease in temperature of the outgoing air, leading me to suspect that the working components are in some type of idle or reduced state.


----------



## Jacob S (Apr 14, 2002)

I hear the characteristics of the hard drive when it is working as if data was being sent and stored onto it, just as a computer hard drive makes sound when it is working on doing something.


----------



## Jacob S (Apr 14, 2002)

1.2 million hours = 50,000 days = 137 years

This is continuous operation of the hard drive. What about the two tuner receivers having two shows being written to the hard drive at the same time and then a third show being watched at the same? Does this cause three times as much wear on the drive? Still yet this would not be happening all of the time and even if it did it would be a LONG time before it would die. Do those receivers have three arms on them or something? How can it read on three different parts of the hard drive at once?

Also wouldn't some types of hard drives not be this well built? I suppose even if it wasn't it could be 1/10th of that and still be 13.7 years of continuous operation.


----------



## keitheva (Aug 23, 2002)

CAL7 said:


> Are you sure the HDD is spinning? I can't hear mine because the fan is so loud. The fan definitely is constantly on. But, when not in use, I can feel a definite decrease in temperature of the outgoing air, leading me to suspect that the working components are in some type of idle or reduced state.


I can't be sure to be honest. But whatever it is, fan or drive or both, please turn it off when powered-off


----------



## paulcdavis (Jan 22, 2004)

Jacob S said:


> 1.2 million hours = 50,000 days = 137 years
> 
> This is continuous operation of the hard drive. What about the two tuner receivers having two shows being written to the hard drive at the same time and then a third show being watched at the same? Does this cause three times as much wear on the drive? Still yet this would not be happening all of the time and even if it did it would be a LONG time before it would die. Do those receivers have three arms on them or something? How can it read on three different parts of the hard drive at once?
> 
> Also wouldn't some types of hard drives not be this well built? I suppose even if it wasn't it could be 1/10th of that and still be 13.7 years of continuous operation.


Unfortunately Hard drive manufacturers all have their own ways of calculating MTBF which both makes it hard to compare different brands as well as difficult for a single drive user to predict how long their drive will last.

I think the length of the drive warranty is more helpful to the single drive user. Most 250GB dirves have a 3 year warranty and an expected service life of 5 years of continuous use. I don't know the specific model number of the drive in the 921, but I would be surprised if its specifications varied much from the industry standard.

So, even without power down of the drive, the hard drive in the 921 should last until 2009.


----------



## Mark Lamutt (Mar 24, 2002)

I received word from the lead developer this morning that hard drive spin down when the 921 is put into Standby (powered off) is coming. It obviously doesn't do it now, but the feature is in the software pipeline. Time estimate was "a couple of months" for what it's worth. Of course, that's subject to change.


----------



## JoeQ (Dec 17, 2003)

Mark Lamutt said:


> I received word from the lead developer this morning that hard drive spin down when the 921 is put into Standby (powered off) is coming. It obviously doesn't do it now, but the feature is in the software pipeline. Time estimate was "a couple of months" for what it's worth. Of course, that's subject to change.


Thanks for that VERY useful info.

I was told to put it in Standby to help extend the life of the disk but I have not because:

I have the 921 setup so my TIVO can control and record SD stuff from it to keep the 921's disk free for the HD material plus the much better Season Pass,etc. capabilities that the TIVO has.

Now I don't have to worry about the fact that I leave the 921 on 24/7.

Thanks,
Joe


----------

