Comment by Aurornis

Comment by Aurornis 3 days ago

9 replies

I would also prefer having a large number of high capacity SSDs so I could replace my spinning hard drives.

But even the cheapest high capacity SSD deals are still a lot more expensive than hard drive array.

I’ll continue replacing failing hard drives for a few more years. For me that has meant zero replacements over a decade, though I planned for a 5% annual failure rate and have a spare drive in the case ready to go. I could replace a failed drive from the array in the time takes to shut down, swap a cable to the spare drive, and boot up again.

SSDs also need to be examined for power loss protection. The results with consumer drives are mixed and it’s hard to find good info about how common drives behave. Getting enterprise grade drives with guaranteed PLP from large on-onboard capacitors is ideal, but those are expensive. Spinning hard drives have the benefit of using their rotational inertia to power the drive long enough to finish outstanding writes.

oceanplexian 2 days ago

This is going to be a huge anecdote but all the consumer SSD I've had has been dramatically less reliable than HDDs. I've gone through dozens of little SATA and M2 drives and almost every single one of them has failed when put into any kind of server workload. However most of the HDDs I have from the last 10 years are still going strong despite sitting in my NAS and spinning that entire time.

After going deep on the spec sheets and realizing that all but the best consumer drives have miserably low DWPD numbers I switched to enterprise (U.2 style) two years ago. I slam them with logs, metrics data, backups, frequent writes and data transfers, and have had 0 failures.

  • smartbit 2 days ago

    What file system are you using? ZFS is written with rotation rust in mind and assumingely will kill non-enterprise ssd.

cm2187 3 days ago

You can find cheap used enterprise SSDs on ebay. But the problem is that even the most power efficient enterprise SSD (SATA) idle at like 1w. And given the smaller capacities, you need many more to match a hard drive. In the end HDD might actually consume less power than an all flash array + controllers if you need a large capacity.

  • userbinator 2 days ago

    Used SSDs, especially enterprise ones, are a really bad idea unless you get some really old SLC parts. Flash wears out in a very obvious way that HDDs don't, and keep in mind that enterprise-rated SSDs are deliberately rated to sacrifice retention for endurance.

    • cm2187 2 days ago

      Agree on SSD for cold storage, that's not a good idea. But you would be surprised by how little used are typical used enterprise SSDs on ebay. This article matches my experience:

      https://www.servethehome.com/we-bought-1347-used-data-center...

      I bought over 200 over the last year, and the average wear level was 96%, and 95% had a wear above 88%.

      • userbinator a day ago

        Endurance and retention are inversely correlated, and as I mentioned in my original comment, enterprise DC drives are designed to advertise the former at the expense of the latter. The industry standard used to be 5 years retention for consumer and 3 months for enterprise, after reaching the specified TBW. The wear level SMART counter reflects that; "96% remaining" on an enterprise drive may be 40% or less on a consumer one having written the same amount, since the latter is specified to hold the data for longer once its rating has been reached.

        • cm2187 a day ago

          Retention is offline retention. Not online. So not sure what point you are trying to make. If it is that SSDs shouldn't be used for cold storage, yeah I agree, and enterprise SSds aren't designed for cold storage. But you seem to be linking retention to TBW, which are largely orthogonal metrics. If you are going to use the SSDs in a NAS, which by definition are running all the time, why would you even care about the rentention rating?

dleeftink 3 days ago

Curious, what's the use case for wanting your data backed-up without fail? Is it personal archives or otherwise (business) archive related?

Not to say you shouldn't backup your data, but personally I wouldn't be to affected if one of my personal drives errored out, especially if they contained unused personal files from 10+ years ago (legal/tax/financials are another matter).

  • EvanAnderson 3 days ago

    Any data I created, paid to license, or put in significant work to gather has to be backed-up with 3-2-1 rule. Stuff I can download or otherwise obtain again is best effort but not mandatory backup.

    Mainly I don't want to lose anything that took work to make or get. Personal photos, videos, source code, documents, and correspondence are the highest priority.