tangles
Dabbler
- Joined
- Jan 12, 2018
- Messages
- 33
Hi All,
My eyes lit up when I saw that dedupe blocks can now be written to special vdevs, and so I read the Linux man about special allocation classes and there's not a huge amount of info that I could see about dedupe in this area. (I'm yet to test in a VM)
Q1. If I create a pool with special vdevs, enable deduplication on the pool, I'm assuming that the dedupe tables (DDTs) would be written to the special vdevs along with the other default blocks described.
What happens if the space on the special vdevs fills up? would the DDT then spew over onto other (slower) vdevs like it does with the other classes? I'm assuming yes.
Q2. How big are dedupe blocks?
I see there's an optional flag to exclude DDTs from special vdevs, but not the other way around to exclude all other types of blocks except dedupe blocks. Whether this is desirable or not is not is something else to ponder I guess, but is it possible to use the small block flag to exclude all blocks except DDT blocks? I'm thinking it isn't possible.
Background to this is a Graphic Design business… Designers are notorious for duplicating a previously similar job for a client to get the core files needed such as logos, themes etc and so am wondering about enabling dedupe with special allocation vdevs now that crazy amounts of ram aren't necessary.
Thoughts?
My eyes lit up when I saw that dedupe blocks can now be written to special vdevs, and so I read the Linux man about special allocation classes and there's not a huge amount of info that I could see about dedupe in this area. (I'm yet to test in a VM)
Q1. If I create a pool with special vdevs, enable deduplication on the pool, I'm assuming that the dedupe tables (DDTs) would be written to the special vdevs along with the other default blocks described.
What happens if the space on the special vdevs fills up? would the DDT then spew over onto other (slower) vdevs like it does with the other classes? I'm assuming yes.
Q2. How big are dedupe blocks?
I see there's an optional flag to exclude DDTs from special vdevs, but not the other way around to exclude all other types of blocks except dedupe blocks. Whether this is desirable or not is not is something else to ponder I guess, but is it possible to use the small block flag to exclude all blocks except DDT blocks? I'm thinking it isn't possible.
Background to this is a Graphic Design business… Designers are notorious for duplicating a previously similar job for a client to get the core files needed such as logos, themes etc and so am wondering about enabling dedupe with special allocation vdevs now that crazy amounts of ram aren't necessary.
Thoughts?