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What SMART Stats Tell Us About Hard Drives

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Re: What SMART Stats Tell Us About Hard Drives

#51

Post by CamperBob2 »

teh_klev wrote: post #30
arielhn wrote: post #17

Small nitpicking here, but the moment it popup a modal dialog asking me to enter my email for some kind of subscription I simply close the tab. I do this since three months ago for any unknown website I visit. Such nuisance for what might be a good read.

Shame...you could've just dismissed the popup and not missed out on an interesting article, it's same energy expended but with a nett gain instead of your loss. A small price to pay for BackBlaze willing to share interesting stuff like this and hardly the most egregious examples of this type of thing. Also these types of complaints have been done to death here over the years and are really, really tedious. Please com…

Shame...you could've just dismissed the popup and not missed out on an interesting article

But I don't know that until I've already given up the goods, do I? This approach to life, the universe, and the Internet simply doesn't scale.

Re: What SMART Stats Tell Us About Hard Drives

#52

Post by [deleted] »

koolba wrote: post #33
esaym wrote: post #14

Ten years ago when I was I trying to learn how to "program", I wrote this bash script (to be added into /etc/cron.daily) that dumps a few smart stats that are normally 0 or slow changing, diffs it with the copy from the previous run, and if anything is different (and cron in configured right) it will email you the diff. Every linux machine I touch gets this file dropped onto it. I've replaced many hard drives because…

(Warning pedantic script review) Add a "set -e" to catch errors. Say if the disk can't be read or file can't be written. Why reuse the same temp file? Make a new one with mktemp and auto clean it via an exit trap. As it's written this isn't concurrently safe. Exiting -1 on error? Don't use negatives. Wrap it all in a main() function and use locals instead of global vars.

[deleted]

Re: What SMART Stats Tell Us About Hard Drives

#53

Post by mjevans »

caf wrote: post #41

Operational drives with one or more of our five SMART stats greater than zero – 4.2% This doesn't gel with the prior table, which shows that 4.8% of operation drives have non-zero SMART188 alone.

The data is close enough that it sounds like the sets share a good portion of common data, but that there are exclusive items in one or both sets.

I could easily see one set based on a different time, or another that missed a category of drives (EG one also counts drives from testing / non-production units).

Re: What SMART Stats Tell Us About Hard Drives

#54

Post by cuchulain »

toast0 wrote: post #48
takeda wrote: post #21

Earlier quoted context omitted.

It's interesting that most people rely on the raw values, since the standard does not require them to be meaningful and depending on the vendor it could be anything. I suspect this is because value, worst, threshold columns are kind of confusing to understand.

There aren't too many vendors for spinning disks, and if you have a lot of disks it doesn't take too long to see that the sector count metrics correspond to sectors. In my experience, bad sector count is a good predictor of future trouble, and running disks until they threw read errors (before we were running smart monitoring), they all had lots of bad sectors. That said, there's a threshold, getting to 100 slowly is…

"SSDs though, they just disappear from the bus when they fail"

This isn't always true, and actually shouldn't ever be true - it's a particular failure mode you're seeing, and while it appears to be one common across a number of SSD controllers, it's still a pretty sorry fact that it happens.

All SSDs (at least all not-complete-rubbish ones) report some kind of flash/media wearout indicator via SMART, which isn't necessarily an imminent failure indicator (SSDs will generally continue to work long past the technical wearout point), but is a very strong indicator that you should replace it soon and should probably buy a better one next time.

SSDs do suffer from sector reallocations in the normal way, and the same kind of metric monitoring can be done. It's pretty vendor-specific as to what SMART attributes they report, but attributes like available reserved space, total flash writes, flash erase and flash write failure counts and so on are pretty common.

Re: What SMART Stats Tell Us About Hard Drives

#55

Post by latitude »

Might be a good time to plug my little baby - https://diskovery.io

If you want to have a quick, but in-depth look at your drives, it'll give you lots of data, including the SMART table interpreted in a vendor-specific way. It also understands some RAID setups, and more support for this is upcoming. Windows only, at the moment.

To explain a bit of a context - SMART data comprises a set of attributes and each attribute has a value, a threshold and a raw value. Values are opaque 8-bit somethings that are only meant to be compared to thresholds. When they fall under then, then it may indicate a problem. They aren't really interesting. What's interesting is the "raw" values, but as the name implies, they are vendor-specific and require decoding. Some vendors publish the specs, but most don't. Specs that are published are often incomplete or plain wrong. So there's a LOT of reverse engineering and guesswork involved, which makes writing a SMART tool both frustrating and interesting at the same time. But if you need just the "dying / healthy" indicator, it's a very easy thing to extract from a drive.

Re: What SMART Stats Tell Us About Hard Drives

#56

Post by d3lxa »

As a data scientist, I would be curious to see the application of machine learning to this problem. I'd start with naive Bayes, logistic regression and SVM.

@blackblaze I'm pretty sure you can automatize a large portion of your investigation that way.

Re: What SMART Stats Tell Us About Hard Drives

#57

Post by djsumdog »

sn wrote: post #24
esaym wrote: post #14

Ten years ago when I was I trying to learn how to "program", I wrote this bash script (to be added into /etc/cron.daily) that dumps a few smart stats that are normally 0 or slow changing, diffs it with the copy from the previous run, and if anything is different (and cron in configured right) it will email you the diff. Every linux machine I touch gets this file dropped onto it. I've replaced many hard drives because…

I'm not sure why you wouldn't use smartd, which has sane defaults, can immediately alert based on arbitrary smart properties changing, and also handles scheduling smart tests. An arbitrary command can be run instead of sending email. For example, reallocated sectors are not alerted on by default, so we added '-R 5!' to our smartd config. The full config we have is: DEVICESCAN -a -s (L/../../6/01) -l selftest -l error…

My familiarity with SMART was on the POST screen. I never ran any daemons; I didn't know they were a thing. Like so many other nerds that grew up in the 90s, we've all experienced data loss. At the best it was just some porn and the worst were those rare VHS tapes you ripped of random high school crap.

I feel like there were enough tools for users to simply monitor SMART stats, or awareness of how it works. Even in this article, it seems like a lot of analysis to see if reported flags are significant.

Re: What SMART Stats Tell Us About Hard Drives

#58

Post by djsumdog »

latitude wrote: post #55

Might be a good time to plug my little baby - https://diskovery.io If you want to have a quick, but in-depth look at your drives, it'll give you lots of data, including the SMART table interpreted in a vendor-specific way. It also understands some RAID setups, and more support for this is upcoming. Windows only, at the moment. To explain a bit of a context - SMART data comprises a set of attributes and each attribute…

Has anyone ported your work to Linux or MacOS? I guess not since iIt looks like it would be very OS specific. It looks like an incredible tool.

Re: What SMART Stats Tell Us About Hard Drives

#59

Post by lazyjones »

alphapapa wrote: post #43
esaym wrote: post #14

Ten years ago when I was I trying to learn how to "program", I wrote this bash script (to be added into /etc/cron.daily) that dumps a few smart stats that are normally 0 or slow changing, diffs it with the copy from the previous run, and if anything is different (and cron in configured right) it will email you the diff. Every linux machine I touch gets this file dropped onto it. I've replaced many hard drives because…

This is basically what smartmontools does: /var/log/syslog:Oct 6 08:14:10 hostname smartd[573]: Device: /dev/sda [SAT], SMART Usage Attribute: 190 Airflow_Temperature_Cel changed from 61 to 62 /var/log/syslog:Oct 6 09:44:10 hostname smartd[573]: Device: /dev/sda [SAT], SMART Usage Attribute: 190 Airflow_Temperature_Cel changed from 62 to 61 /var/log/syslog:Oct 6 10:14:10 hostname smartd[573]: Device: /dev/sda [SAT],…

I respectfully disagree. Judging from the output you posted, it just spams logfiles with irrelevant info, training the user to ignore it, so they will never notice when important values change in an interesting way.

Re: What SMART Stats Tell Us About Hard Drives

#60

Post by djsumdog »

teh_klev wrote: post #30
arielhn wrote: post #17

Small nitpicking here, but the moment it popup a modal dialog asking me to enter my email for some kind of subscription I simply close the tab. I do this since three months ago for any unknown website I visit. Such nuisance for what might be a good read.

Shame...you could've just dismissed the popup and not missed out on an interesting article, it's same energy expended but with a nett gain instead of your loss. A small price to pay for BackBlaze willing to share interesting stuff like this and hardly the most egregious examples of this type of thing. Also these types of complaints have been done to death here over the years and are really, really tedious. Please com…

Yea, I already run uBlock Origin. I don't mind mailing list popups. The authors should make sure someone gets at least 50% through the page before showing them. I have a feeling that will get a high click through rate ... err...sign up rate.

I hate ads. I block all of them. But I will help your crowd-funding or Pateron or buy some swag to help you promote your thing.

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