SSD +HD in RAIDZ1

[DanielKlein]

I have a raidZ1 with 3x2tb HDDs, but one of my Hard drives started spitting out some errors and failed the Long Smart test twice.
Since SSDs are cheap right now and they are very reliable I was thinking about replacing the failing HDD with an SSD.
My question is, with only 1 SSD, may I see some faster read or write speed sometimes? (since every file is in 2 drives I guess not, but maybe)
And if in the future I replace other HDD and have 2xSSDs and 1 HD, maybe?

ps.: This Zpool is for 'maps' and some other files that I read a lot but rarely write new ones, I guess this is the perfect situation for SSDs longevity, right? Was thinking about buying the cheapest 2tb SSDs I can find (Crucial MX300 or Crucial MX500) or should I spend a little more and get something more reliable like the Samsung 860 EVO?

 

[Chris Moore]

I have a raidZ1 with 3x2tb HDDs, but one of my Hard drives started spitting out some errors and failed the Long Smart test twice.
Since SSDs are cheap right now and they are very reliable I was thinking about replacing the failing HDD with an SSD.

If you think a 2TB SSD is cheap, you could send me a couple.

My question is, with only 1 SSD, may I see some faster read or write speed sometimes? (since every file is in 2 drives I guess not, but maybe)
And if in the future I replace other HDD and have 2xSSDs and 1 HD, maybe?

I suppose that you might see a tiny bit of performance boost, but it is not likely. The storage pool you have is made up of a single vdev and in ZFS, vdev performance is limited by the slowest drive in the vdev and pool performance is an aggregate of all vdevs in the pool.
That means, if you want more performance, adding more vdevs is the way to get it, or replace all three drives with faster drives, but you are still limited by the slowest drive.

ps.: This Zpool is for 'maps' and some other files that I read a lot but rarely write new ones, I guess this is the perfect situation for SSDs longevity, right?

It is true that reading is much less damaging to SSDs than writing, but in the configuration you have, each SSD would have just about half of the total data written to it, if you had three SSDs.

Was thinking about buying the cheapest 2tb SSDs I can find (Crucial MX300 or Crucial MX500) or should I spend a little more and get something more reliable like the Samsung 860 EVO?

To receive the benefit of the additional speed, you would need to spring for three, and the cheap ones should be good enough.
Just ensure that they are rated for use in an array.