search

openzfs / openzfs-docs

OpenZFS Documentation
https://openzfs.github.io/openzfs-docs/
135 stars 194 forks source link

Can someone please decipher this? #508

Closed systemcrash closed 5 months ago

systemcrash commented 5 months ago

https://github.com/openzfs/openzfs-docs/blob/55a0d1cf73b564a889a3fb616fddf55be0f33f14/docs/Basic%20Concepts/RAIDZ.rst#write

Please elaborate. This smells like a Russian thought it and wrote it roughly in English.

What is "full stripe width"? If you made an assumption of what "full" means - please define it.

What is "one block write"? Abstract, singular? What on earth does "has a write IOPS of one slowest disk because of that" mean?

"of one slowest disk"? Because of "that" what is "that" here?

If I am to take a guess (which a user should not be doing, because the user reads the documentation in order that they not guess) - were you trying to say something like the following?:

A stripe spans all drives in the array. A one block write will write the stripe part onto each disk.
A RAIDZ vdev has a write IOPS of the slowest disk in the array in the worst case because writes to each disk must be completed before successive writes on the other, faster disks can commence.
gmelikov commented 5 months ago

Please elaborate. This smells like a Russian thought it and wrote it roughly in English.

You're right, I've made it as a draft, and it existed far too long in this state.

I hope to rework it someday, https://www.reddit.com/r/zfs/comments/ujba3i/does_allocation_overhead_still_exist_with/ looks like a well-worded example to use.

Feel free to send PRs if you're interested, I'd be glad to review them!

systemcrash commented 5 months ago

Hello :)

The link is generally regarding compression, while the essence of the text in this issue is about write performance. The linked text might be added under a separate heading, so.... let's tackle the issue first.

Does my proposed text capture the essence of what you intended to say?

gmelikov commented 5 months ago

@systemcrash feel free to review me, thank you https://github.com/openzfs/openzfs-docs/pull/509/files