Hey folks! i'm reaching out because i've heard 2 different statements to the same question. This pertains to zfs not being like hardware raid (or any other raid for that matter).
i'm building a truenas core 13.x nas (latest stable) and I had an idea: i have 5 x4TB spinners in one of those 5 bay raid cages that pops in the 3x5.25 drive bays.
i thought i could also add a single 4TB SSD as a hot spare because if it's just sitting there waiting to go into service when a spinner dies, it's not using any power and not wearing out like a spinner does.
i thought the way it works/worked was, upon the death of one of the spinners in the raidz1 array, the SSD (of equal size, of course) would temporarily take over. zfs would use the parity yadda yadda and rebuild the dead drive on the SSD. then, upon replacement of the dead spinner with another spinner (same model as the other spinnners), the data would be automatically moved from the SSD to the new drive, the SSD would go back into an idle state and await to be reused when the next drive dies..
some of you are probably asking why i would do it like this? well, if i'm away from my nas and i can't be there to immediately install a replacement drive, the SSD would help it along (like a donut spare tire) until i get back to replace the drive. the nice thing about this would be, again, no wear while the SSD is at idle and a theoretically much quicker rebuild time.
I can see how this wouldn't work with hardware raid or any other software raid, but considering ZFS seems to have a lot of intelligence built into it, i thought maybe it's possible.
I've been told "yes, it can do that" by someone on a truenas forum. i've been told "no, it can't do that" by someone who has a TON of experience, just none with ZFS.
Thanks for your patience!
i'm building a truenas core 13.x nas (latest stable) and I had an idea: i have 5 x4TB spinners in one of those 5 bay raid cages that pops in the 3x5.25 drive bays.
i thought i could also add a single 4TB SSD as a hot spare because if it's just sitting there waiting to go into service when a spinner dies, it's not using any power and not wearing out like a spinner does.
i thought the way it works/worked was, upon the death of one of the spinners in the raidz1 array, the SSD (of equal size, of course) would temporarily take over. zfs would use the parity yadda yadda and rebuild the dead drive on the SSD. then, upon replacement of the dead spinner with another spinner (same model as the other spinnners), the data would be automatically moved from the SSD to the new drive, the SSD would go back into an idle state and await to be reused when the next drive dies..
some of you are probably asking why i would do it like this? well, if i'm away from my nas and i can't be there to immediately install a replacement drive, the SSD would help it along (like a donut spare tire) until i get back to replace the drive. the nice thing about this would be, again, no wear while the SSD is at idle and a theoretically much quicker rebuild time.
I can see how this wouldn't work with hardware raid or any other software raid, but considering ZFS seems to have a lot of intelligence built into it, i thought maybe it's possible.
I've been told "yes, it can do that" by someone on a truenas forum. i've been told "no, it can't do that" by someone who has a TON of experience, just none with ZFS.
Thanks for your patience!