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Guest Message by DevFuse

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HR34 and 4TB External Drive


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131 replies to this topic

#41 OFFLINE   kevinturcotte

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Posted 20 November 2012 - 12:51 PM

None of the BlacX have any RAID capability so it doesn't matter if the drive is RAID-friendly or not.

At a minimum, any RAID requires at least 2 drives. And it must have a RAID controller in the enclosure. This makes the multiple drives look like a single drive to the DVR. The BlacX Duet is dual drive but does not contain a RAID controller so even though it's only one cable (requiring the host to have a SATA port-multiplier-capable controller) the host software sees it as 2 distinct drives - which we know is useless for a DVR.

For completeness, the WD4000FYYZ is an enterprise drive and is RAID-friendly. The WD4001FAEX is a desktop drive and is not designed for RAID.


Can the HR line deal with RAID 1? Would this impact performance?

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#42 OFFLINE   RunnerFL

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Posted 20 November 2012 - 01:58 PM

Can the HR line deal with RAID 1? Would this impact performance?


I have 2 HR's running RAID1 right now and tested another running RAID5. The one that was running RAID5 is now running RAID0. No issues at all.
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#43 OFFLINE   dpeters11

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Posted 20 November 2012 - 03:27 PM

Don't the risks of raid 0 greatly exceed the benefit?

#44 OFFLINE   RunnerFL

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Posted 20 November 2012 - 04:04 PM

Don't the risks of raid 0 greatly exceed the benefit?


What risk? There's no redundancy but I certainly don't see that as a risk.

It's no different than running off of one drive.
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#45 OFFLINE   dpeters11

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Posted 20 November 2012 - 04:50 PM

I'd see it as less reliable than running it off one. If either drive dies, you lose it. It seems to me there is a greater chance of that happening than one drive.

Of course we're not talking mission critical data here, and we know if the DVR dies, you lose everything essentially. But it's adding one more component to the mix.

#46 OFFLINE   P Smith

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Posted 20 November 2012 - 05:01 PM

that's right and he knew that

#47 OFFLINE   RunnerFL

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Posted 20 November 2012 - 10:20 PM

I'd see it as less reliable than running it off one. If either drive dies, you lose it. It seems to me there is a greater chance of that happening than one drive.

Of course we're not talking mission critical data here, and we know if the DVR dies, you lose everything essentially. But it's adding one more component to the mix.


I don't see it as a risk at all. If you're running off 1 drive and 1 drive fails you lose everything. If you're running RAID0 and you lose 1 drive you lose everything. Like I said before, it's no different than running off one drive.

The odds of 1 of the 2 drives in a RAID0 array failing are the same as 1 drive in a 1 drive setup failing.
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#48 OFFLINE   RunnerFL

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Posted 20 November 2012 - 10:21 PM

that's right and he knew that


Please don't speak for me. I know what I said and meant it.
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#49 OFFLINE   Laxguy

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Posted 20 November 2012 - 10:49 PM

The odds of 1 of the 2 drives in a RAID0 array failing are the same as 1 drive in a 1 drive setup failing.


The odds of each single one failing is the same, but it's twice as likely as there are twice as many drives .
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#50 OFFLINE   RunnerFL

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Posted 20 November 2012 - 10:54 PM

The odds of each single one failing is the same, but it's twice as likely as there are twice as many drives .


But a single failure is still a total loss. If it only takes a single drive failure to lose everything then the odds of you losing everything are the same as a single drive system. Same result, same odds, more space.

I use Enterprise Level drives, odds are lower.
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#51 OFFLINE   Laxguy

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Posted 20 November 2012 - 11:05 PM

Well, I was pretty good at statistics, and heartily disagree, but I think that's where we'll end up unless a math whiz comes along.
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#52 OFFLINE   RunnerFL

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Posted 20 November 2012 - 11:18 PM

Well, I was pretty good at statistics, and heartily disagree, but I think that's where we'll end up unless a math whiz comes along.


How is a single drive failure different than a single drive failure? :lol:
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#53 OFFLINE   P Smith

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Posted 20 November 2012 - 11:43 PM

Well, I was pretty good at statistics, and heartily disagree, but I think that's where we'll end up unless a math whiz comes along.


You're right , there is clearly demonstrated missing knowledge.

The rule is simple: total reliability is a product of multiplying all part's reliability.

Say one HDD has reliability equal 90% [0.9], then two same HDD will has total 0.81 ie 81%. Any engineer knows that and it shouldn't be discussed here.

#54 OFFLINE   harsh

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Posted 21 November 2012 - 09:07 AM

I'd see it as less reliable than running it off one. If either drive dies, you lose it. It seems to me there is a greater chance of that happening than one drive.

If experience of the hardcore users is any indication, the DVR will likely die before either of the hard drives dies.

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#55 OFFLINE   harsh

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Posted 21 November 2012 - 09:08 AM

Any engineer knows that and it shouldn't be discussed here.

There are few engineers here so it bears repeating.

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#56 OFFLINE   Diana C

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Posted 21 November 2012 - 09:58 AM

You're right , there is clearly demonstrated missing knowledge.

The rule is simple: total reliability is a product of multiplying all part's reliability.

Say one HDD has reliability equal 90% [0.9], then two same HDD will has total 0.81 ie 81%. Any engineer knows that and it shouldn't be discussed here.


True, over the total lifetime of the two drives, and that is the calculation for RAID 0. However, the whole point of RAID 1 is to exploit the fact that the failure of a drive is likely to happen at any point over the entire expected lifetime of the drive (as stated in the MTBF rating). Therefore, the likelihood of both drives failing at the same time is vanishingly small. I honestly don't see the point of RAID 0 in a DVR use case. The DVRs don't need the extra drive performance, and buying two 1TB drives is more expensive than one 2TB drive.

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#57 OFFLINE   dpeters11

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Posted 21 November 2012 - 10:58 AM

If experience of the hardcore users is any indication, the DVR will likely die before either of the hard drives dies.


Very possible. This is one reason I'm not doing a raid setup until the policy changes.

#58 OFFLINE   Rich

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Posted 21 November 2012 - 11:52 AM

Well, I was pretty good at statistics, and heartily disagree, but I think that's where we'll end up unless a math whiz comes along.


Validate that. Tell me what the odds are on hitting a home run the next time you get up after hitting a home run. And if you do hit a home run in successive at bats, what are the odds on hitting a third one?

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#59 OFFLINE   Rich

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Posted 21 November 2012 - 11:54 AM

If experience of the hardcore users is any indication, the DVR will likely die before either of the hard drives dies.


Agreed and that's the problem we all face. Make the HRs and HDDs compatible with each other within an account and the problem goes away instantly.

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#60 OFFLINE   RunnerFL

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Posted 21 November 2012 - 11:55 AM

I honestly don't see the point of RAID 0 in a DVR use case.


Space. 2 x 2TB = 4TB.
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