# Upgrade internal drive or just add USB



## Kirkinsd (Jul 15, 2007)

I'm about to order a Premier. I've upgraded Series 1 Tivos in the past and am comfortable with the process. I read that the new JMFS cd is even easier than the old MFSTools...

But, why not just add an external USB drive and be done with it?


Thanks in advance...


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## steve614 (May 1, 2006)

Warranty issues aside, adding an external hard drive adds an extra layer of possible failure.

With an external hard drive attached, you're relying on two hard drives to work properly instead of just one.


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## dwit (May 5, 2004)

Tivo cannot utilize a USB drive. Tivo/Premiere can only use a compatible ESATA drive(in plug and play fashion), of which there is only one choice.


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## mr.unnatural (Feb 2, 2006)

steve614 said:


> Warranty issues aside, adding an external hard drive adds an extra layer of possible failure.
> 
> With an external hard drive attached, you're relying on two hard drives to work properly instead of just one.


Seriously? That's like saying that owning two Tivos doubles your chance of failure since you have two drives. Many of us have been running dual-drive Tivos for over a decade with virtually no problems whatsoever. Your post is pure supposition with no basis of fact. It sounds like common sense on the surface, but actual long-term usage tends to reveal otherwise.

The fact is, if a hard drive dies in a Tivo you're probably going to lose recordings. If you've got two drives and one dies then you're in the same boat. You've got the same risk of drive failure with only one drive as you do with two. The only real mitigating factor is heat and whether your power supply can handle two drives.

The only drive failures I've ever had in a Tivo were in single-drive configurations, and the OEM drive that came with it was the one that usually failed.


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## SullyND (Dec 30, 2004)

mr.unnatural said:


> Seriously?


How many of the TiVo specific WD drives have you run?


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## steve614 (May 1, 2006)

mr.unnatural said:


> Seriously?


I didn't say adding an external hard drive doubles your chance of failure.

Only that it adds an extra point of _possible_ failure.

When a problem arises, which is easier to diagnose, a Tivo with one hard drive or a Tivo with two hard drives?


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## lessd (Jan 23, 2005)

mr.unnatural said:


> Seriously? That's like saying that owning two Tivos doubles your chance of failure since you have two drives. Many of us have been running dual-drive Tivos for over a decade with virtually no problems whatsoever. Your post is pure supposition with no basis of fact. It sounds like common sense on the surface, but actual long-term usage tends to reveal otherwise.
> 
> The fact is, if a hard drive dies in a Tivo you're probably going to lose recordings. If you've got two drives and one dies then you're in the same boat. You've got the same risk of drive failure with only one drive as you do with two. The only real mitigating factor is heat and whether your power supply can handle two drives.
> 
> The only drive failures I've ever had in a Tivo were in single-drive configurations, and the OEM drive that came with it was the one that usually failed.


The point being made is a single drive TiVo that has a hard drive go bad is easier to deal with then a two drive TiVo, because in the latter case you don't know what drive is your problem, and when you find out then do you replace the bad drive and keep the old one or replace both. The TP uses about 20 watts, an external drive may use another 10 watts or a 50% increase, putting in a 2TB drive may only increase the power by 1 to 2 watts over the OEM drive, and most new non OEM drives have a 2 to 5 year warranty.


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## Kirkinsd (Jul 15, 2007)

I do like the idea of pulling the original drive as a backup. If I open the case after the initial warranty will Tivo still swap the thing out for $150 if something else happens or am I SOL?
If you disconnect the ESATA drive I know you lose all recordings but can you easily "divorce" and go back to single drive capacity?

TIA


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## L David Matheny (Jan 29, 2011)

steve614 said:


> I didn't say adding an external hard drive doubles your chance of failure.
> 
> Only that it adds an extra point of _possible_ failure.


Actually, if both drives are equally reliable, having two should exactly double your chances of having a failure.


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## L David Matheny (Jan 29, 2011)

Kirkinsd said:


> I do like the idea of pulling the original drive as a backup. If I open the case after the initial warranty will Tivo still swap the thing out for $150 if something else happens or am I SOL?
> If you disconnect the ESATA drive I know you lose all recordings but can you easily "divorce" and go back to single drive capacity?
> 
> TIA


Technically, opening the case probably voids the warranty. But as a practical matter, if you later put back the original drive and return the TiVo for an unrelated failure (without mentioning the drive swap), TiVo shouldn't complain and probably won't. Most failures are drives and power supplies anyway. And yes, you can disconnect the external drive and revert to only the internal drive, losing your recordings in the process.


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## steve614 (May 1, 2006)

Kirkinsd said:


> I do like the idea of pulling the original drive as a backup. If I open the case after the initial warranty will Tivo still swap the thing out for $150 if something else happens or am I SOL?


This is one of those grey areas like "don't ask, don't tell" in the military. 

It's a risk you take. TiVo can look at logs they get from your DVR and see what capacity the hard drive is. I think 2 or 3 members here have reported that they were refused warranty service because of this.

Don't let this discourage you from upgrading before the warranty is completely over.
Odds are you will be able to fix the Tivo yourself for less than it costs to do a warranty exchange.

Here's the scenario:
You upgrade your hard drive *and put the original in a safe place*.
At the first sign of a problem, you take out the upgraded hard drive and put the original back in.
This can tell you whether or not the hard drive was the problem.
If the problem persists, let the Tivo call home several times before you call TiVo customer service so that the "fresh" logs will show the original hard drive size.

Keep in mind this is not guaranteed to work. No one knows how far back TiVo archives the individual DVR logs.
You might get a determined CSR itching to find a reason to refuse a warranty exchange.


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## mr.unnatural (Feb 2, 2006)

Personally, I've never worried about Tivo's warranty because it's pretty much a joke anyway. I don't think I've ever waited for the warranty to expire before swapping out the OEM drive for a larger one. If the drive died I replaced it myself and never even considered dealing with Tivo or DirecTV. Why pay $150 for a refurbished Tivo when a replacement drive cost me much less? Back in the days before Tivo started using an LBA48 kernel we had to use dual drives if we wanted more than 137GB capacity. Failure rates weren't any worse than using single drives from what I recall.

The point is, if a drive has a finite lifespan it's going to die whether it's a single drive or paired with a 2nd drive. The lifespan of any drive is not dependent on any other drive it may be paired with. Statistically speaking, there is a greater chance of failure with two drives. Realistically, however, your Tivo has the same chance of survival with two drives as it does with one. 

Think about it this way, if a drive is supposed to have a life expectancy of five years and you install two identical drives in the same Tivo, it's not unrealistic to expect both drives to last five years. The reality is, all drives are not equal. Some arrive DOA and others will keep on running well after the expiration date. 

If a drive is going to die, it's going to die, period. Don't get hung up on statistics and using one vs. two drives in a Tivo. If you need the storage and two drives work best for your situation, go for it.


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## jrtroo (Feb 4, 2008)

L David Matheny said:


> Actually, if both drives are equally reliable, having two should exactly double your chances of having a failure.


Not true. I no longer have the detailed knowledge of the calculation, but failure probabilities are NOT additive, even if the basis are the same. It will be somewhat less than double.


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## Kirkinsd (Jul 15, 2007)

Thanks everyone for the help.
Now I'm just waiting for another Tivo sale so I can pick up a Premiere 4 with lifetime for cheaper than full retail.


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## lessd (Jan 23, 2005)

jrtroo said:


> Not true. I no longer have the detailed knowledge of the calculation, but failure probabilities are NOT additive, even if the basis are the same. It will be somewhat less than double.


You are correct,
IE. the chance that if you purchased 1000 drives and ran them all for at 24/7 that you would have at least one failure by year 1 is about 95%, so for two drives the odds of one failing under the normal 4 to 5 year running time would only goes up about 10% to 20 %, but you now have two power supplies that could fail, you will have more reliability with a single drive upgrade in any TiVo.


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## lrhorer (Aug 31, 2003)

mr.unnatural said:


> Seriously? That's like saying that owning two Tivos doubles your chance of failure since you have two drives.


First of all, odds do not add that way. If the odds of a given drive failing are N, then the odds of either one of two drives failing are 1 - (1 - N)^2. For very small values of N, however, this does approach 2 x N.



mr.unnatural said:


> Many of us have been running dual-drive Tivos for over a decade with virtually no problems whatsoever.


'Not relevant. The question is not whether a TiVo with 2 drives can possibly last a long time or even whether a specific TiVo with 2 drives can possibly outlast a given TiVo with only one drive. The answer to both questions is, "Yes". The simple fact is the two drive TiVo is more likely to fail in a given time frame than a 1 drive TiVo. How much more likely depends on the drives used, the environment, and the time frame. Over a 50 year time frame, both TiVos are extremely likely to die, but the single drive TiVo is just a tiny hair less likely to fail. Over a one week time frame, neither one is at all likely to fail, but the 2 drive TiVo is in fact almost 2 times as likely to fail as the one drive TiVo. If for the sake of argument, we assume either drive has a 50% chance of failing within 5 years, then the odds either one (or both) will fail during that 5 year time period is 75%. 'Not double, but significantly higher.



mr.unnatural said:


> Your post is pure supposition with no basis of fact. It sounds like common sense on the surface, but actual long-term usage tends to reveal otherwise.


I'm afraid neither one is of much value in this case, but the mathematics are inexorable. Once again assuming a 50% failure rate over a 5 year period, given 100 TiVos running one drive and another 100 TiVos running two drives but otherwise identical, approximately 50 of the first group will fail and 75 of the second group will fail. OTOH, roughly 25 of the TiVos in the second group will outlast more than 50 of the TiVos in the first group.



mr.unnatural said:


> The fact is, if a hard drive dies in a Tivo you're probably going to lose recordings. If you've got two drives and one dies then you're in the same boat.


No, one is not. If the secondary drive fails, one loses only the programs recorded after the second drive was added (which could be all of them, of course). If the primary drive fails, the TiVo is dead in the water. Thus, while the failure of a drive in a 2 drive Tivo is more likely than a single drive TiVo, the impact of the failure may be lower.



mr.unnatural said:


> You've got the same risk of drive failure with only one drive as you do with two.


You need to think about that statement for a bit. It is absurd. If it were true, then the risk of failure for a TiVo with 3 drives would also be the same. Precisely the same would be true of one with 10 drives, or 100 drives, or 1000 drives. Clearly you don't have a good grasp of probabilities, but if you really believe the odds of failure of any number of drives in a group of 1000 drives is the same as the odds of any single drive failing, then you *really* have no clue of what "random" means.



mr.unnatural said:


> The only real mitigating factor is heat and whether your power supply can handle two drives.


Replace "The only real" with "Two" and you are closer to something meaningful. Increased operating temperatures will on average reduce the lifespan of all the components, although perhaps not by much. An increased current draw is indeed more stressful to the power supply, and will on average reduce its life, as well.



mr.unnatural said:


> The only drive failures I've ever had in a Tivo were in single-drive configurations, and the OEM drive that came with it was the one that usually failed.


Which proves nothing except that is the way the dice rolled for you. It does mildly suggest the drives you purchased independently may have been of superior quality to the OEM drive. Your experience does not by any means prove the statement, but it is not an extraordinary notion, and perhaps not even an unlikely one.


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## lrhorer (Aug 31, 2003)

lessd said:


> You are correct,
> IE. the chance that if you purchased 1000 drives and ran them all for at 24/7 that you would have at least one failure by year 1 is about 95%, so for two drives the odds of one failing under the normal 4 to 5 year running time would only goes up about 10% to 20 %, but you now have two power supplies that could fail, you will have more reliability with a single drive upgrade in any TiVo.


Um, uh-uh.

If the odds of a single drive failing in a 1 year time frame is .01% (meaning 1 drive out of 1000 will fail in one year - approximately what you said), then the odds of either one or both drives failing in that 1 year time frame is .019999%. The odds don't quite double, and the increase is .009999%. There is no way to easily extrapolate that to a 5 year timeframe, since failure rates are not linear with time.


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## lrhorer (Aug 31, 2003)

jrtroo said:


> Not true. I no longer have the detailed knowledge of the calculation, but failure probabilities are NOT additive, even if the basis are the same. It will be somewhat less than double.


It's pretty simple, actually. If one event has a likelihood of N, then the odds of it happening precisely twice are N^2. The odds of it happening precisely three times is N^3, etc.

To see this, simply think of a family of two siblings. Each sibling has a 50-50 chance of being male and the same of being female. The number of possible combinations are:

M - M
M - F
F - M
F - F

Add them up, and we see the odds of both being male is 25% and not surprisingly the odds of both being female are the same. 50% of the time, one will be male and the other female. If we make it a family of 3 siblings, then the possible combinations are thus:

M - M - M
M - F - M
M - F - F
M - M - F
F - M - M
F - F - M
F - F - F
F - M - F

Now the odds of all three being male are 1 in 8 (or 1 in 2^3) and the odds of all three being female are likewise 1 in 8. The odds of them not being all the same are 3 in 4.

In the case of the failing hard drive, if the odds of any single drive failing are N, then the odds of it NOT failing are 1 - N. Given a group of P drives, the odds of none of them failing is (1 - N) ^ P, and the odds of at least one failing is 1 - (1 - N)^P. For very small values of N, this value approaches, but is always less than, N x P.


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## lrhorer (Aug 31, 2003)

L David Matheny said:


> Actually, if both drives are equally reliable, having two should exactly double your chances of having a failure.


So if the odds of one drive failing is 80%, then the odds of any one of two drives failing is 160%?

Nyet. I repeat, 1 - ( 1 - N )^2.

If the odds of a single drive failing is 80%, then the odds of either or both of a pair failing is 96%.


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## lrhorer (Aug 31, 2003)

mr.unnatural said:


> Failure rates weren't any worse than using single drives from what I recall.


And what study is it, exactly, that you recall?



mr.unnatural said:


> The point is, if a drive has a finite lifespan it's going to die whether it's a single drive or paired with a 2nd drive.


That's irrelevant. It's also imponderable. There is no way to know when a drive will fail. We may only speak about the failure rate and the odds of failure during any given time period. If that period is one which is low compared to the MTBF of a drive, then the odds of a failure in either one of two drives is almost twice that of a single drive. At the MTBF point, the odds are 75% for two drives vs. 50% for one drive.



mr.unnatural said:


> The lifespan of any drive is not dependent on any other drive it may be paired with.


That is the entire point. Just because one drive does not fail does not mean the other also will not.



mr.unnatural said:


> Statistically speaking, there is a greater chance of failure with two drives. Realistically, however, your Tivo has the same chance of survival with two drives as it does with one.


That is completely nonsensical. Exactly what do you think is the difference between "statistically" and "realistically"? Statistical analyses are always based upon real-world data.



mr.unnatural said:


> Think about it this way, if a drive is supposed to have a life expectancy of five years and you install two identical drives in the same Tivo, it's not unrealistic to expect both drives to last five years.


1. There is no such thing as "supposed to last 5 years". If the MTBF of a drive is 5 years, then roughly half of the drives in a batch will last 5 years or more. If the batch is large enough, some won't last 5 minutes, while others may last 20 years.

2. It is unrealistic to expect even one drive to last 5 years, in this case. The expectation is the *AVERAGE* life expectancy of a large number of drives is 5 years. There is also a fairly weak expectation that a drive rated for 10 years MTBF will possibly last longer than one with a 5 year MTBF. Again, if the odds of losing one drive is 50%, then the odds of losing either one or both is 75%. Note also this could mean one drive dies in 1 year and the other in 6, or that both die in under a year.



mr.unnatural said:


> If a drive is going to die, it's going to die, period. Don't get hung up on statistics and using one vs. two drives in a Tivo. If you need the storage and two drives work best for your situation, go for it.


The simple fact is, however, on average the two drive TiVo will fail sooner. That said, drive failure rates are low enough that even doubling the odds of a failure is not a huge gamble.


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## mr.unnatural (Feb 2, 2006)

lrhorer said:


> Which proves nothing except that is the way the dice rolled for you.


And that about sums up my entire argument. You can show me all the statistics you want about whether a single Tivo drive will have a better chance of survival vs. two drives. The point is, you can't make any guarantees that drive A will have a shorter lifespan by itself or if it's paired with drive B. It might, but the impact will be minimal at best. Buying a hard drive is like rolling the dice. Sometimes you pick a winner and sometimes you roll craps.

I've owned and modified literally dozens of Tivos over the past decade or so. The only drive failures I encountered were in single-drive configurations. Granted, the number of units used for comparison is relatively small for any test group, but this is what I experienced in real life.

If using two drives is the only option available to you then all I'm saying is there's no compelling reason not to go with two drives. It's worked for me and lots of other Tivo owners.



lrhorer said:


> The simple fact is, however, on average the two drive TiVo will fail sooner. That said, drive failure rates are low enough that even doubling the odds of a failure is not a huge gamble.


It took you long enough to finally agree with what I've been saying all along.


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## lrhorer (Aug 31, 2003)

mr.unnatural said:


> And that about sums up my entire argument. You can show me all the statistics you want about whether a single Tivo drive will have a better chance of survival vs. two drives.


No one said it will, additional heat aside. That is the whole point. The TiVo most cetainly and definitely will, on average, irrespective of what you believe.



mr.unnatural said:


> The point is, you can't make any guarantees that drive A will have a shorter lifespan by itself or if it's paired with drive B.


What you are missing is that statement is precisely equal to saying the TiVo will not last as long. The only way an average TiVo with two drives can last as long on average as a TiVo with one drive is if the pairing Drive A with Drive B somehow makes them both last nearly twice as long on average.



mr.unnatural said:


> It might, but the impact will be minimal at best. Buying a hard drive is like rolling the dice. Sometimes you pick a winner and sometimes you roll craps.


Again, that is the entire point. I do not know the rules of craps, but the odds of rolling any particular total on a pair of dice are perfectly well known. With an honest pair of dice, one will roll snake eyes every 36 throws on average, and one will roll boxcars precisely as often. Seven is by far the most common throw, since there are 12 different combinations by which one may obtain a seven, making the odds of rolling it 1:3. You are saying statistics don't matter and then with the next breath comparing it to a roll of the dice, which is purely statistical.



mr.unnatural said:


> I've owned and modified literally dozens of Tivos over the past decade or so. The only drive failures I encountered were in single-drive configurations. Granted, the number of units used for comparison is relatively small for any test group, but this is what I experienced in real life.


Which again is not relevant to the discussion at hand. First of all, we would have to determine what the relative longevity of OEM versus after-market drives might be, and possibly make brand comparisons. If all the drives were perfectly identical, however, and we could find 100 people who like you have owned both single and dual drive TiVos, the majority of those people would have had two drive TiVos fail more than single drive TiVos.

Think for a moment about what you re saying. You are saying that, somehow, if every one of those 2 drive TiVos had been split up into 2 TiVos, they would not have lasted as long.



mr.unnatural said:


> If using two drives is the only option available to you then all I'm saying is there's no compelling reason not to go with two drives. It's worked for me and lots of other Tivo owners.


That is probably true, but it is a very different thing from saying a two drive TiVo is guaranteed, or even likely, to last as long as a 1 drive TiVo. Given the rather low failure rate of hard drives, putting two in a system is, as I said before, not a huge gamble. It's a good thing, too, because I have personally owned systems with up to 15 drives in them. Some companies have systems with hundreds of drives in them. Those systems typically have hard drive failures every few months, despite using drives with much greater MTBF ratings.



mr.unnatural said:


> It took you long enough to finally agree with what I've been saying all along.


I am not agreeing with what you said all along. I am saying your conclusion accidentally has merit, despite being based upon completely incorrect logic. It's not a good way to operate, but in this case the end result is tolerably acceptable.


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## L David Matheny (Jan 29, 2011)

lrhorer said:


> So if the odds of one drive failing is 80%, then the odds of any one of two drives failing is 160%?
> 
> Nyet. I repeat, 1 - ( 1 - N )^2.
> 
> If the odds of a single drive failing is 80%, then the odds of either or both of a pair failing is 96%.


As had already been pointed out, the odds of either of two identical drives failing are not "exactly double" the odds of one drive failing (my brain fart), but they are close for small values. If the odds of one failing during any month are (say) 1%, then the odds of at least one failing during that month would be (1 - 0.99^2) or 1.99%, which is nearly double.

And if you use drives that have an 80% monthly failure rate or even an 80% yearly failure rate, I don't want any. Of course, if you pick a long enough time period, like 10 years, the failure rate could approach 100%.


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## scole250 (Nov 8, 2005)

If everyone is done arguing about the probability of disk failure, and this may have already been mentioned, but...
1. upgrading the internal is easy.
2. Not sure if you can add an external without buying Tivo's or using another service like Weaknees.
3. Once you add an external, not sure if you can upgrade the internal yourself.

I'd upgrade the internal first.


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## mr.unnatural (Feb 2, 2006)

scole250 said:


> If everyone is done arguing about the probability of disk failure, and this may have already been mentioned, but...
> 1. upgrading the internal is easy.
> 2. Not sure if you can add an external without buying Tivo's or using another service like Weaknees.
> 3. Once you add an external, not sure if you can upgrade the internal yourself.
> ...


1. Yes it is.

2. I believe there's a list of external enclosures and external drives in a sticky thread somewhere that are compatible with S3 and later models. It's pretty much plug and play, but there's a menu option you have to select to add the drive, IIRC.

3. You can certainly upgrade the internal drive beforehand. You'd have to divorce the external drive and probably lose any recordings if you wanted to upgrade the internal drive after adding an external one.


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## mr.unnatural (Feb 2, 2006)

lrhorer said:


> Think for a moment about what you re saying. You are saying that, somehow, if every one of those 2 drive TiVos had been split up into 2 TiVos, they would not have lasted as long.


That's not at all what I said. I said that the only drives I've had fail were in single drive configurations. It just happens that those single drives were OEM drives and not upgrades. Perhaps I should have stated that I've rarely had an upgraded drive fail, regardless of configuration.


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## unitron (Apr 28, 2006)

mr.unnatural said:


> 1. Yes it is.
> 
> 2. I believe there's a list of external enclosures and external drives in a sticky thread somewhere that are compatible with S3 and later models. It's pretty much plug and play, but there's a menu option you have to select to add the drive, IIRC.
> 
> 3. You can certainly upgrade the internal drive beforehand. You'd have to divorce the external drive and probably lose any recordings if you wanted to upgrade the internal drive after adding an external one.


The original S3 can use externals other than the TiVo approved WD models.

(it's a long story)

The S3 HD, S3 HD XL, and all S4 machines have to use the WD, 'cause they got a very small list of of WD drive signatures and it has to be one of those few models or it won't accept it.


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