Regarding draid needing spare, I have two questions. See the test screenshots
- Why does draid need to resilver twice
- The background color is green, and there is no difference in recovery time when there is spare or spare.
Not sure what you mean.
The only real advantage of dRAID is the integrated hot spare(s). You use space available across all disks, leaving enough for 1 or more disks to fail. Then using that space to perform a fast re-silver from scattered sources to scattered hot spare space.
That allows the integrated hot spare to be re-silvered faster, since it is not a single write target.
Whence the failing disk is removed & replaced, another re-silver has to occur at a slower speed since it is mostly a write target.
Was that what you mean?
Please understand, their are uses for dRAID. But, the average home or small business user probably does not have a need for it. There is even a down side to dRAID. If I understand it correctly, all dRAID writes are full stripe width, even if the amount of data is smaller. That is closer to traditional RAID-3/4/5/6. ZFS' RAID-Zx does not do that, and will reduce stripe width to the amount of data.
Some people here in the forums don’t suggest regular hot spares except when the server is remote. Partly because you have another re-silver to “replace” the hot spare. And partly because a hot spare is using up some of its power on time… So a tested cold spare could be preferred in some cases.
I used Google Translate, please forgive me. Thanks for your reply, but I don’t understand 2 points
- Looking at the 4th and 5th lines, the resilvering time is almost the same without hot spare and with hot spare
- There is 1 hot spare, and I checked it through zfs status, why is it resilvered twice
(The first time is to remove a disk on the physical machine, and the second time is to replace it on the WEB)
Sorry, I just don’t understand enough about dRAID to answer your questions.
I replied to give you general information about dRAID, hoping it would assist in you figuring out the answers. Someone else with more knowledge of dRAID as implemented in ZFS will have to answer your questions.
It is explained in the documentation you were linked in a different thread of yours. Try to find someone with computer knowledge to translate.
Spares are not a single device but the space is spread over the dRAID.