Drive replacement considerations

I’m running a personal NAS for many years now. The hardware is described by Supermicro board/Atom 2550/16GB EEC/3x SATA WD RED 3TB.

The board has 2 SATA3 ports and 4 SATA2 ports. I use a consumer grade SSD to boot. The three RED’s are 1 pool in raidz1.

Although outdated, it still does its job nicely.

I started with FreeNAS 9 and have upgraded over time to latest TrueNAS Scale. I run a handful of containers and have some SMB shares for files. The jewels stored here are the family pictures and some documents. I have regular snapshots and a daily backup to backblaze.

Performance is less important to me than availability and integrity of the data. Current performance is good enough.

Total data usage is 1.9TB, of which 1.3TB is downloaded movies. Which I do not backup to backblaze and which I can consider to delete (at least large part of it).

I sometimes need to replace a disk. My current disks are 5 years, 3 years and 2 years old.

This morning I woke up with a scrub alert: Message ID: ZFS-8000-9P — OpenZFS documentation. This usually is the moment where I decide to replace the disk. I didn’t check yet, but usually it turns out to be the oldest disk.

Now I could just replace for another WD RED, but I’m also thinking more about energy consumption and heat and looking into SSD’s.

Prices here are roughly:

  1. WD RED HDD 3TB EUR. 125,-
  2. WD RED SSD 2TB EUR. 150,-
  3. WD RED SSD 4TB EUR. 330,-
  4. cheapest consumer grade SSD 4TB: WD Blue SA510 EUR. 250,-
  5. cheapest consumer grade SSD 2TB: Lexar NS100 EUR. 100,-

So, my options are:
1a. replace 1 faulty disk with the same HDD: EUR. 125,-, but this doesn’t help me in migrating to SSD’s
1b. replace 1 faulty disk with RED SSD 4TB: 330 euro (so eventually I spend 1000 euro on SSD’s)
1c. replace 1 faulty disk with consumer grade SSD 4TB: 250 euro
2a. replace 3 HDD’s with 3 RED SSD’s 2TB: 3x150 euro
2b. replace 3 HDD’s with 3 consumer grade 2TB ssd’s: 3x100 euro
2c. replace 3 HDD’s with 3 consumer grade 4TB ssd’s: 3x250 euro
3. migrate current setup to mirror HDD: no costs involved, immediate lower power consumption, next failing disk I can replace by 4TB SSD, or I replace both by 2TB SSD and accept that I need to delete some movies in the future
4. maybe I missed an option?

So I’m basically thinking about option 1a or 2a.

I also believe 2b might be a proper solution as I read that consumer grade SSD’s are fine as long as there is not too much writing going on.

I can’t find much information about RAIDz1 vs mirror; discussions are more about performance than reliability. But it would be really nice if I can safely use 1 disk less.

What are your thoughts on this, what would you advise in this case?

No doubt, SSDs are very competitive once you consider the cost of power as long as the dataset size is moderate.

You could also shuck a drive from an external enclosure but the fear there is getting a SMR drive in the bargain.

These days I prefer buying used from a quality reseller like I get a 5-year warranty, good service whenever I have had to send back a drive due to smart errors piling up. Plus $76 for 10TB is a pretty good deal.

Maybe there are similar resellers somewhere in Europe?

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If you are buying a HDD, make sure that you buy a CMR drive.

WD state clearly that their RED drives are NOT suitable for ZFS (because they are SMR drives). You need RED PLUS or RED PRO for ZFS.

@Protopia , thanks for pointing this out. I’m aware of this and are buying the plus/pro variants, but should have mentioned this explicitly not to confuse future readers.

@Constantin , the cost of power in my case is a bit different than you might expect. I have solar panels which basically provide it for free. Even during the night, as the energy I produce but not use is deducted from the energy that I use from the net when the solar panels are not supplying enough power. This is going to end in (probably) 2 years, and we have some new more complex calculations coming up, but basically this was the case for the last couple of years. Anyway: lower energy usage is in the end always good.

Would you use consumer grade SSD’s as well?

And what are thoughts about raidz1 vs a mirror, with respect to reliability (availability and integrity of data)?

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We also have net metering where I live, where the excess of our solar panels is credited towards consumption in off hours. Like you, I expect the utilities will strike back at some point to better recover transmission and distribution charges.

For the time being, displacing power at 33 cents / kWh while also getting SREC credits to the tune of about $350 / MWh is very attractive. Our small system is now covering about 50% of our power needs and the SREC credit will pay for a further 25%.

If I were in your shoes, I’d look into buying two pairs of s3510 SSDs used from a reputable reseller and then set them up as two sets of mirrors or even a z1. They are inexpensive (<$100 for 1.6TB), bulletproof, use very little power. I use a 4-way mirror of them as my sVDEV.

Yup - nothing like asking for advice and deliberately limiting the details you disclose.