Me and my friend were discussing this the other day about how he said RAID is no longer needed. He said it was due to how big SSDs have gotten and that apparently you can replace sectors within them if a problem occurs which is why having an array is not needed.
I replied with the fact that arrays allow for redundancy that create a faster uptime if there are issues and drive needs to be replaced. And depending on what you are doing, that is more valuable than just doing the new thing. Especially because RAID allows redundancy that can replicate lost data if needed depending on the configuration.
What do you all think?
Unless I’m misunderstanding, that sounds like you’re worried about the write hole, which RAIDZ doesn’t have
It’s mostly a matter of making sure any writes that are interrupted part way through (power failure, etc) are kept alive until the issue has been resolved. The raid controller caches everything until the write is complete.
It’s not so much about disks being out of sync, but more about preventing data loss.
RAIDZ is copy-on-write, and will notice and correct parity discrepancies if interrupted partway through. Doesn’t help if you don’t get at least one copy of the data written, but I’d take RAIDZ and a UPS over a hardware raid any day
And at the scale I’m operating, I’ll take hardware raid over raidz any day. I did some performance benchmarking when initially building these clusters, and beegfs really doesn’t like raidz.
I use raidz at home, though.