Electronics > Projects, Designs, and Technical Stuff

Researching practical HDD reliability/solutions...

(1/4) > >>

MyHeadHz:
I am trying to consolidate relevant data on hard disk drives (HDD's) with the purpose of making practical recommendations for anyone (end-user) who has an interest in hard disk storage and longevity solutions.  I am focusing only on the home-user or small NAS user, not enterprise solutions- though most of the sources are just the opposite.  Being an idiot, I would greatly appreciate some input.

Background (amazon links are for visual/type reference only): I've had several hard drives fail recently, including several drives known to be quite reliable- so I must be doing something wrong.  Current and previous strategies include:

1.  arbitrary vibration-dampened single-bay off-the-shelf sealed USB drives (no fans/accessibility)
2.  dual-bay enclosures with fans (you add your own drives), non-dampened
3.  non-dampened  external single-bay USB enclosures with fans
4.  non-dampened external single-bay enclusures, without fans
5.  standard SATA mounted drives screwed directly to computer tower frame (no dampening).
(It is worth noting that I've never tried RAID, a dedicated NAS box, or internally-mounted drives that were dampened.)

I've had more failures (dead drives and SMART failures) with solutions 1 and 2, which seemed counter-intuitive to me- especially considering I used high-quality enterprise drives with those.  My initial intent was to find a scalable method to decouple the HDD's from vibration to solve the problem.  Several people strongly asserted that vibration/sound dampening decreases hard drive longevity and write/speed reliability.  This seemed counter-intuitive, but it did happen to agree with my anecdotal drive failure experiences.  There were a lot of differing opinions on various forums, so I began researching journal sources.  It turned out to be quite the rabbit hole. 

Chan (2012) differentiates between vibrations (predictable, consistent frequencies and amplitudes) and externally-produced shock.  These are different problems with different solutions.  For the home-user, it is practical to decouple fans or other external vibration sources from the HDD.  I will do that where I can.  Another thing Chan notes is that vibrations that can affect ideal HDD performance can be as low as 2Hz.

Park, (2012) focuses on dampening solutions for 2.5" (laptop HDD's) with regard to shock and vibration tolerance.  Many papers seemed to focus on one or the other, but Park relates the two.   Park includes a chart of transmissibility using various rubber-based decoupling solutions.  Park also includes a chart relating frequency to the position error signal, which relates read/write errors to amplitude and frequency.  As with the other papers, there was no discussion about which frequencies/factors were most problematic to overall long-term hard drive life.  However, as this was a scientific paper, it was intended to be used more as a reference for people designing relevant devices, so the relevant parameters would vary greatly.  As much as I would like to assume that the PES and long-term failure rate are related, I cannot necessarily support that assumption with this data.  Also, all the data in Park was for 2.5" drives, so I suspect the frequency charts will probably be significantly different for 3.5" drives.

Again, for my purposes, the external forces can be understood and mitigated through isolation.  That leaves issues originating from the drive itself.  The primary sources for these seem to be sinusoidal vibration (platter balance), vibrations from the mechanical head movement, and any resonance issues.

I had a hard time finding information about overall long-term drive reliability.  I found several sources that reference "ideal mounting" of hard drives as being large stationary objects, such as granite slabs (Kelly, (2016)) or ~20kg metal blocks (Suwa (1999). However, I was unable to find why that is used as a standard.  I saw reports referencing it going back into the 90's that I couldn't find live sources of.   Would the conclusions learned from such old technology even still be relevant?

My main concern is that although it reduces measurable vibration, does that necessarily mean the drives will be more reliable?  Could it be that the energy is dissipated into the disk/actuator/head/etc itself, causing stress or strain that eventually reduces lifespan, instead of being safely emitted elsewhere?  I suppose this is where my lack of knowledge of the subject comes in.  Any input would be greatly appreciated!

In the mean time, I'll be trying to figure out some way to reliably mount HDD's in landscaping bricks.

There is still other useful knowledge to apply from what I've learned.  1.  Don't use dual enclosures.  2.  Don't use rubber/soft mounts- they are good for drops, but reduce lifespan otherwise.  3.  Physically isolate fans and other sources of vibration.  4.  I forgot to mention it above, but a major factor in reliability was start/stop cycles.  So I will probably set up a FreeNAS box to address that.  All that means that I will need to redo my entire storage system.  Ohh, well.

I read into the BackBlaze reliability statistics as well.  A lot of their methodology may not apply to normal users.  Those racks are big and heavy, and probably do well to dampen most resonances, or particular resonances.  So their numbers may or may not translate well into desktop system use- which they explicitly state.  There aren't any "control" drives outside of their normal 45 drive enclosures to compare against.




Chan, 2012 - http://seelab.ucsd.edu/papers/cschan_gm13.pdf
Park, 2012 - https://sci-hub.tw/10.1007/s00542-012-1592-z
Kelly, 2016 - https://45drives.blogspot.com/2016/09/everything-you-need-to-know-about-hard.html
Suwa, 1999 - https://sci-hub.tw/10.1109/20.753800

edit:typos

magic:

--- Quote from: MyHeadHz on February 24, 2019, 08:10:47 am ---I've had more failures (dead drives and SMART failures) with solutions 1 and 2, which seemed counter-intuitive to me- especially considering I used high-quality enterprise drives with those.  My initial intent was to find a scalable method to decouple the HDD's from vibration to solve the problem.  Several people strongly asserted that vibration/sound dampening decreases hard drive longevity and write/speed reliability.  This seemed counter-intuitive, but it did happen to agree with my anecdotal drive failure experiences.  There were a lot of differing opinions on various forums, so I began researching journal sources.  It turned out to be quite the rabbit hole.
--- End quote ---
Interesting.
I think a possible problem with soft suspension is that vibration generated by any mass imbalance in the motor or platters shakes the whole disk and hammers on the bearings of the head arm. It likely increases the effort of keeping the heads on track too so if the disk is already starting to fall apart it could increase the rate of read retries and write errors. Pure speculation.
I'm not sure how forces acting on spindle bearings are affected. Probably it makes no difference whether the disk chassis is stationary and the center of mass of the motor/platter system orbits the rotation axis or vice versa.
Anyway, I have one disk suspended on rubbers and it seems to be doing fine so far. But I did it for noise suppression, not out of concerns about external vibrations affecting the disk. Maybe I should consider mounting it normally.

jopapeca:
Hi,

I have some FreeNas/Nas4Free boxes running 24/7 using standard drives usually Western Digital in Raid configuration. The boxes are mounted in a rack with other servers. The only issues is drive failure after some large hours, but since the drives are consumer grade I consider it just normal. So we just implemented a strategic swap after some time (1 year) before failure, since the drive cost is much much less then using enterprise grade drives and performance is almost the same for our application.
I had one mechanical failure after a very short time, due to someone unplugging the wrong plug at the rack power while the Nas4Free was performing a large copy.

Enviado do meu SM-G935F através do Tapatalk

texaspyro:
The first thing to do is check out Backblaze's hard drive reliability reports.  They use zillions of consumer grade HDDs in their data centers and regularly post their drive failure stats.

Jeroen3:
Don't be fooled by Backblazes numbers.
They use a low sample count for certain drives. They might find a manufacturing issue on them if half of the units fail, but other than that their numbers don't tell much.
For example, you might say "seagate bad" since those are the only ones that failed a lot. But those are also the ones they bought in >20k lots.

Navigation

[0] Message Index

[#] Next page

There was an error while thanking
Thanking...
Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod