On: Hard Drive Reliability Review for 2015

[samstave]

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...