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Backblaze hard drive reliability stats for Q3 2016

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Re: Backblaze hard drive reliability stats for Q3 2016

#101

Post by sigstoat »

discreditable wrote: post #37
ars wrote: post #35

Earlier quoted context omitted.

I did, I picked HGST because of their reports. No problems so far. When you buy hard disks ONLY buy from Amazon or Newegg directly - never buy from a 3rd party seller on their site. Especially for hard disks there is too much fraud, and for a hard disk especially the risk of data loss makes it just too risky (unlike other items).

> When you buy hard disks ONLY buy from Amazon or Newegg directly - never buy from a 3rd party seller on their site. Agreed. A few times I've purchased third-party disks and found (via SMART data) that the drives were well used despite not being sold as such.

Just returned a "new" drive with 31k power on hours. I should've known when the drive wasn't in a standard WD antistatic bag.

Re: Backblaze hard drive reliability stats for Q3 2016

#102

Post by vinay427 »

leejoramo wrote: post #8

How are people using Backblaze's excellent hard drive reliability reports in making purchasing decisions? For example when I search for HGST HMS5C4040ALE640 on Amazon I get a dealer selling old out of warrantee drives as new. https://www.amazon.com/HGST-MegaScale-HMS5C4040ALE640-Coolsp... I get similar results with many of the other drives listed and with other websites such as NewEgg.

I also bought an HGST portable drive recently as they had one of the cheapest 7200rpm USB 3.0 offerings available online.

Re: Backblaze hard drive reliability stats for Q3 2016

#103

Post by kalleboo »

dom0 wrote: post #62
kardos wrote: post #57

Earlier quoted context omitted.

Is there a reason you couldn't use a second set of actuators?

There's kinda not enough space: https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Sa... You could probably do it if the platter diameter were reduced, which would then accordingly reduce capacity as well. At that point you could just as well use two drives and also get lower overall failure probability. Or you use SSD caches, or memory caches, ...

No problem, just bring back the Bigfoot https://en.wikipedia.org/wiki/Quantum_Bigfoot

Re: Backblaze hard drive reliability stats for Q3 2016

#104

Post by baruch »

hinkley wrote: post #65
dom0 wrote: post #40

Earlier quoted context omitted.

Well, uh, yes. No one really expects that rotational rust will get much faster, and in fact history shows that, compared to the increase in density, the increase in transfer rates are laughable at best. Between 1990 and today you are probably looking at a 20 000 times increase in density, yet transfer rates only increased around a factor of around 150-200. [In fact, from the early 1960 to today it's only a factor of…

That's not entirely true. Higher density means more data per track, not just more tracks per disk. You get an entire track per revolution so a track with more data is more MBps. So linear reads on a higher density drive are faster, and semi-linear accesses (ie, reading two files that are next to each other) do get faster. I remember reading a story about a guy who built a drive array with high capacity 7200 RPM drive…

Short stroking helps get more performance from the disk, at least in terms of latency. The bandwidth change occurs because the density is fixed and there are more blocks on the outer rings per track compared to the inner rings so in one revolution you can read more tracks and you don't need to change tracks so often.

You parent comment is right though, there are only small changes in bit density on the track in recent years so the bandwidth is not improving by much.

Re: Backblaze hard drive reliability stats for Q3 2016

#105

Post by [deleted] »

dom0 wrote: post #62
kardos wrote: post #57

Earlier quoted context omitted.

Is there a reason you couldn't use a second set of actuators?

There's kinda not enough space: https://upload.wikimedia.org/wikipedia/commons/thumb/7/75/Sa... You could probably do it if the platter diameter were reduced, which would then accordingly reduce capacity as well. At that point you could just as well use two drives and also get lower overall failure probability. Or you use SSD caches, or memory caches, ...

[deleted]

Re: Backblaze hard drive reliability stats for Q3 2016

#106

Post by rzzzt »

mahyarm wrote: post #75
dom0 wrote: post #40

Earlier quoted context omitted.

Well, uh, yes. No one really expects that rotational rust will get much faster, and in fact history shows that, compared to the increase in density, the increase in transfer rates are laughable at best. Between 1990 and today you are probably looking at a 20 000 times increase in density, yet transfer rates only increased around a factor of around 150-200. [In fact, from the early 1960 to today it's only a factor of…

How about the stupid idea of making a minimum block size be a multiple of the number of platters to write to. The block is divided evenly amongst all platters and are always at the same parallel track/sector. That way you can multiply the read/write speeds to be a function of the number of platters. Instead of 50-100MB/s, you can get 4-8x the speed in large linear transfers, which helps get dead racks back up faster…

Google's paper on datacenter hard drives addresses this point -- it's easier to do this and other tricks with a set of disks than attempting it within the confines of a single drive.

https://news.ycombinator.com/item?id=11172876

Re: Backblaze hard drive reliability stats for Q3 2016

#107

Post by jerguismi »

SteveNuts wrote: post #79
brianwski wrote: post #54

Earlier quoted context omitted.

Disclaimer: I work at Backblaze. We securely wipe the drives, then we sell them to a "used hard drive reseller".

I know it's a lot easier to wholesale resell them, but it'd be so awesome if you could dedicate a portion to be sold to the homelabbers among us.

I don't know how that would be more awesome, essentially spending effort towards the upper middle-class hobbyists. I would rather see them sell them directly to the highest bidder and focus the effort on improving their business, or give the drives to charity.

Re: Backblaze hard drive reliability stats for Q3 2016

#108

Post by dom0 »

hinkley wrote: post #65
dom0 wrote: post #40

Earlier quoted context omitted.

Well, uh, yes. No one really expects that rotational rust will get much faster, and in fact history shows that, compared to the increase in density, the increase in transfer rates are laughable at best. Between 1990 and today you are probably looking at a 20 000 times increase in density, yet transfer rates only increased around a factor of around 150-200. [In fact, from the early 1960 to today it's only a factor of…

That's not entirely true. Higher density means more data per track, not just more tracks per disk. You get an entire track per revolution so a track with more data is more MBps. So linear reads on a higher density drive are faster, and semi-linear accesses (ie, reading two files that are next to each other) do get faster. I remember reading a story about a guy who built a drive array with high capacity 7200 RPM drive…

> Higher density means more data per track, not just more tracks per disk.

I literally said that:

> Most density increases are achieved by packing more tracks onto the platter, while storing more sectors per track plays a minor role.

Re: Backblaze hard drive reliability stats for Q3 2016

#109

Post by dom0 »

digler999 wrote: post #77
kardos wrote: post #73

Earlier quoted context omitted.

I was thinking of a Frankendrive with 5 actuators, which can do 5 parallel reads/writes, as long as they don't overlap. But the new dimensions would probably be the roadblock.

I was going to ask this too, but start with a simple 2nd voice coil on the opposite side of the spindle, keep the 3.5" form factor and just make it longer. My guess is the motion of one actuator would disrupt the airflow of the other, since we're talking about micrometer-ish (?) mechanical tolerances. This might be able to be mitigated by interleaving which side each arm wrote to. So the left arm's heads address the…

> since we're talking about micrometer-ish (?) mechanical tolerances.

Even less than that. Tracks are 100-300 nanometers wide; the head flies about 3-6 nm above the platter.

The actuator mechanism literally locks onto the signal encoded in the magnetic track and follows it as the platter rotates underneath the R/W head.

Re: Backblaze hard drive reliability stats for Q3 2016

#110

Post by [deleted] »

eye2sky wrote: post #84
mahyarm wrote: post #75

Earlier quoted context omitted.

How about the stupid idea of making a minimum block size be a multiple of the number of platters to write to. The block is divided evenly amongst all platters and are always at the same parallel track/sector. That way you can multiply the read/write speeds to be a function of the number of platters. Instead of 50-100MB/s, you can get 4-8x the speed in large linear transfers, which helps get dead racks back up faster…

You cannot read from multiple platters in parallel. When you are aligned to read from a certain track on a certain side of a platter, you are not necessarily aligned on all platters. This head mechanism is not accurate enough for that.

[deleted]
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