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How long do disk drives last?

blog.backblaze.com

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Re: How long do disk drives last?

#111

Post by gambiting »

driverdan wrote: post #86
gambiting wrote: post #26

Earlier quoted context omitted.

Yeah, if that was true that would be completely against EU regulations,so you could sue manufacturers and win millions. So if you have any proof that they are doing that, you are practically a millionaire, I don't know why are you not on your way to the court yet.

How so? That is how warrantees work. They're designed to protect you against premature failure. Unless it's a necessary competitive advantage no company is going to warrantee something past its expected lifetime. And in that case it's going to be included in the price.

Designing a device to fail after a pre-determined amount is very much against the law. Expected lifetime is different, but this is not what the previous poster was suggesting.

Re: How long do disk drives last?

#112

Post by xixi77 »

marcosdumay wrote: post #71
toyg wrote: post #50

If some of them live a long, long time, it makes it hard to compute the average. Also, a few outliers can throw off the average and make it less useful. Proper statistical analysis would help you there.

> Proper statistical analysis would help you there. Yes, if you know the probability distribution. If you don't know the distribution, you can not calculate your confidence, and thus can not do a proper statistical analysis. And, guess what, nobody knows the probability distribution of hard drive failures. That's exactly what they are trying to find out.

There are actually many methods in survival analysis -- just as in the rest of statistics -- that do not impose strict distributional assumptions, and account for the fact that many drives are still operational. But as someone else mentioned, the median is also a good statistic to report :)

Re: How long do disk drives last?

#113

Post by j45 »

Managing harddrives, especially in redundant setups can be helped in one small way if you're sure to:

1) select the make and model of drive you want

2) buy the same model of drives from multiple vendors which have different serial and build numbers.. even if you're buying two drives, buy each from separate locations or vendors.

3) mix up the drives to make sure they don't die. place stickers of purchase date and invoice number on each drive to keep them straight.

This all.. because when one drive goes due to a defect or hitting a similar MTBF, other ones with a close by serial number or build number can tend to die around the same time for similar reasons.

From owning hard drives over 8 or 9 generations of replacing or upgrading since the 90's on all types of servers, desktops and laptops: The day you buy a new piece of equipment is the day you buy it's death. Manage the death proactively as it gets more and more tiring to deal with it each time.

Re: How long do disk drives last?

#114

Post by baruch »

dmourati wrote: post #103
baruch wrote: post #96

Earlier quoted context omitted.

They do a different tradeoff here. There is no need for a hardware raid if performance is not your main concern (and even if it is hardware raid is no panacea), if they save everything to disk before acknowledging it they don't need a battery and I'm not sure what you refer to as cap. Their hardware design is specifically geared towards their use-case and I applaud them for knowing how to optimize for their use-case.…

cap=capacitor. http://www.lsi.com/downloads/Public/MegaRAID%20SAS/MegaRAID%... Edited to add: They've optimized for hardware purchase price and given up reliability (HW RAID, battery, cap), performance, and maintainability. The strange thing is the overall cost of the storage system is driven by power, not purchase price. Smarter RAID controllers, like I link above, let you manage power by spinning down disks as they…

Their use case is mostly write-once, they fill the data and never delete. The write-rate is probably more limited by the upload speeds of its users than the disk bandwidth and the multitude of port-multipliers that they use. Recovery is anyway mostly about copying all the user data to an external HDD and ship that which is a lot less performance critical as shipping the HDD will take a lot longer than reading all the data from across their systems.

As for saving power by spinning down disks, it is likely to be useful to them and is completely possible even in SW RAID though it requires some managing to perform effectively.

There isn't much that is applicable directly to most other use-cases but if your data is mostly sitting idle and you only need occasional access to it the backblaze pod is a nice design. If you care about performance and do not deploy multiple pods with redundancy between them you are not likely to be happy with the result.

Re: How long do disk drives last?

#115

Post by dmourati »

brianwski wrote: post #110
dmourati wrote: post #88

Ugh. Backblaze is one of those companies with an extraordinarily poor design that they flout and "open source" as if anyone would follow their lead. Take a look at the physical design of their system and combine that with the published data. Consider that to remove any harddrive from their setup requires physically removing a 4u rackmount storage pod from the rack. http://blog.backblaze.com/2011/07/20/petabytes-on-a-…

Disclaimer: I work at Backblaze but I'm on the software side, I barely ever touch the storage pods anymore. It is not true that the pod team must remove the 4U server from the rack. It is slid out like a drawer (no tools required, takes maybe 10 seconds). The drive or motherboard is then replaced, then you slide the drawer back in. So the 4U server must slide 18 inches one way, but zero cables have to be unplugged or…

Thanks for the clarification. That the PODs were on rails was never made clear to me. Still, I count that as "physically removing a 4u rackmount storage pod." Those suckers cannot be light. 10 seconds sounds rather fast. I don't imagine you could do it that fast for any of the upper pods.

While I don't recommend them outright, we settled on 3U boxes from SuperMicro. http://www.supermicro.com/products/chassis/3u/837/sc837e26-r...

We somewhat affectionately dubbed them "mullets" as in business in the front, party in the rear.

They make 4U devices as well. Cost was about $1000. We added LSI Megaraid 9280 controllers, about another $1500 and ran min-SAS back to a controller node responsible for 4 JBODs.

Re: How long do disk drives last?

#116

Post by crpatino »

ffrryuu wrote: post #106

Has blackblaze budgeted for the cliff failure rate that is coming?

Based on the linear extrapolation they make over the third year failure data into the future (to calculate an estimated half life of roughly 6 years), I would say they probably have not.

A little statistics is a dangerous thing.

Re: How long do disk drives last?

#117

Post by ffrryuu »

crpatino wrote: post #116
ffrryuu wrote: post #106

Has blackblaze budgeted for the cliff failure rate that is coming?

Based on the linear extrapolation they make over the third year failure data into the future (to calculate an estimated half life of roughly 6 years), I would say they probably have not. A little statistics is a dangerous thing.

Well, as long as they IPO before that happens...

Re: How long do disk drives last?

#118

Post by leeoniya »

sp332 wrote: post #87
leeoniya wrote: post #75

Earlier quoted context omitted.

i'm not sure where you're getting that info: http://www.newegg.com/Product/Product.aspx?Item=N82E16822236... http://www.amazon.com/WD-Red-NAS-Hard-Drive/dp/B008JJLZ7G been running 3x of these in a raid-5 NAS, no issues so far (not that it's any kind of indicator on a system which idles as a backup all day)

About half of the Newegg reviews are 3-eggs or lower. And even some of the 5-egg reviews mention dead drives! They only got 5 eggs because of Newegg's easy return policy. The drives are clearly unreliable.

great :(

Re: How long do disk drives last?

#119

Post by secabeen »

dmourati wrote: post #115
brianwski wrote: post #110

Earlier quoted context omitted.

Disclaimer: I work at Backblaze but I'm on the software side, I barely ever touch the storage pods anymore. It is not true that the pod team must remove the 4U server from the rack. It is slid out like a drawer (no tools required, takes maybe 10 seconds). The drive or motherboard is then replaced, then you slide the drawer back in. So the 4U server must slide 18 inches one way, but zero cables have to be unplugged or…

Thanks for the clarification. That the PODs were on rails was never made clear to me. Still, I count that as "physically removing a 4u rackmount storage pod." Those suckers cannot be light. 10 seconds sounds rather fast. I don't imagine you could do it that fast for any of the upper pods. While I don't recommend them outright, we settled on 3U boxes from SuperMicro. http://www.supermicro.com/products/chassis/3u/837/s…

It's a different trade-off. The Supermicro boxes use drive trays, so swapping a hard drive requires a datacenter tech to handle the tray mounting and unmounting. The PODs just drop drives right in. They've traded off tray mounting work for chassis sliding.

Re: How long do disk drives last?

#120

Post by secabeen »

dmourati wrote: post #103
baruch wrote: post #96

Earlier quoted context omitted.

They do a different tradeoff here. There is no need for a hardware raid if performance is not your main concern (and even if it is hardware raid is no panacea), if they save everything to disk before acknowledging it they don't need a battery and I'm not sure what you refer to as cap. Their hardware design is specifically geared towards their use-case and I applaud them for knowing how to optimize for their use-case.…

cap=capacitor. http://www.lsi.com/downloads/Public/MegaRAID%20SAS/MegaRAID%... Edited to add: They've optimized for hardware purchase price and given up reliability (HW RAID, battery, cap), performance, and maintainability. The strange thing is the overall cost of the storage system is driven by power, not purchase price. Smarter RAID controllers, like I link above, let you manage power by spinning down disks as they…

Actually, Glacier is probably backed mostly by tape with a disk cache. Writing then becomes cheap, as you can grab the next blank tape, but restores take a while, as they have to pull the specific tapes needed from whatever storage system they're using.
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