On: Hard Drive Reliability Review for 2015

[budmang]

From our experience, we've found 5 SMART stats that are useful in predicting failure: https://www.backblaze.com/blog/hard-drive-smart-stats/

Many SMART stats aren't particularly useful in predicting failure as they simply correlate to the age of the drive in some fashion.

Also, here is our data on every single SMART stat for all of the drives we have: https://www.backblaze.com/blog-smart-stats-2014-8.html

Gleb (CEO, Backblaze)

[samstave → budmang]

Gleb,

First thanks for all your company's sharing of such data, as well as the pod open platform. Kudos.

Second, can you do a Writeup specifically and only about SSDs?

Thanks

[atYevP → samstave]

Hi! Yev from Backblaze here -> Yes, we only report the stats of what we have in our environment. As much as we'd love to have a test of SSDs in a pod (augmented for SSDs of course) they're just not feasible from a cost per GB perspective. Hopefully sometime though :)

[geostyx → samstave]

As far as I know, they don't really use SSD's because of the higher cost/GB. So they probably don't have much to say about them :/

[ekianjo → geostyx]

Is there any good use case of having ssds in a data center, if you did not care about cost?

[masklinn → ekianjo]

Input/Output rate, bandwidth and IO roundtrip delay.

* even the slowest SSDs have significantly higher I/O rates than the best mechanical drives, and the comparison between best-in-class mechanical and enterprise-class PCIe SSDs is just ridiculous: a 15K SAS drive will do 200 IOPS, a high end SSD will do a million

* 15K SAS drives will top out around 250MB/s on bulk sequential reads (that's a best-case scenario), high-end PCIe SSD are in the 2.5GB/s range

* HDDs have a latency of 10~20ms, SSDs have a latency of 100~200µs (RAM has a latency of ~100ns)

[hrrsn → ekianjo]

They're used in DCs plenty when speed is required

[jen729w → hrrsn]

Yep, I work for a very large government department here in AU and we have a tiny bit of SSD in our DC for the stuff that really needs it.

It's probably not 5% of our total storage, though.

[samstave → ekianjo]

IOPs

[samstave → geostyx]

They had some in some of their other reports but too small a population it would seem...

[sandGorgon → budmang]

This is awesome!

Have you productized these learnings in a a powertop-like tool for Linux?

Smartmontools are not intuitive enough for the layman to use in any meaningful way.. And backblaze has really built some serious learning here that could be of use to everyone.

[agumonkey → budmang]

Will this turn into a tradition ?