Comment by AceJohnny2
13 hours ago
Tangential, but about this:
> I am creating a RAIDZ1 (RAID 5) zpool. That means 1 drive redundancy in-case of failure
A friend once told me that RAID5 has a high latency cost, because every Write requires a Read to update the stripes across all drives, and while this made sense when drives were expensive, nowadays you might as well do a RAID10 instead, and trade space for latency.
Is this still true with ZFS RAIDZ1?
It's complicated, but https://jro.io/capacity/ actually walks you though how it works, towards the middle of the page.
``` Unlike traditional RAID5 and RAID6 implementations, ZFS supports partial-stripe writes. This has a number of important advantages but also presents some implications for space calculation that we'll need to consider. Supporting partial stripe writes means that in our 7wZ2 vdev example, we can support a write of 12 total sectors even though 12 is not an even multiple of our stripe width (7). 12 is evenly divisible by +1 (3 in this case), so we don't even need any padding. We would have a single full stripe of 7 sectors (2 parity sectors plus 5 data sectors) followed by a partial stripe with 2 parity sectors and 3 data sectors. This will be important because even though we can support partial stripe writes, every stripe (including those partial stripes) need a full set of p parity sectors. ```
> and while this made sense when drives were expensive
I don't have the answer to the latency question, but HDDs have shot up in $/TB over the last couple years too. They are once again kind of expensive.
The RAID5 write hole is not present in RAIDZ1 I believe.
RAIDZ1 will add more stress to the consumer ssd's as to enterprise one due to surprinsingly different hardware. Consumer ssd's life times are calculated on a 8 hour shift (the tbw) and enterprise are calculated on 24/7.
Please - dont - use - consumer ssd's - with zfs raidz1