tests using fast SSDs/optanes for metadata combined with raidz2?

[c77dk]

Hi,

Anyone testet the impact of combining raidz2 vdevs (3+ vdevs?) with metadata only special vdevs?
Not much info on that combination yet - only managed to find something from one of the first previews of the feature in ZFS back from .... 2018 I guess?

 

[Yorick]

We know the impact of metadata-only L2ARC, assume it’s similar with a special vdev with the difference that all data needs to be written new to take advantage.

for just metadata, persistent L2ARC might be the better choice. At the very least for testing: You can find out whether your use case / application benefits, and if not, remove L2ARC again.

Once you’ve added a special alloc vdev mirror, it’s there for good.

 

[jasonsansone]

Hi,

Anyone testet the impact of combining raidz2 vdevs (3+ vdevs?) with metadata only special vdevs?
Not much info on that combination yet - only managed to find something from one of the first previews of the feature in ZFS back from .... 2018 I guess?

I will be deploying this in the coming weeks. I will try to remember to report back on performance.

 

[kspare]

i've found that the meta special drive works better with iscsi than with nfs if that helps at all?

for our terminal servers we have about 11tb of data, and under nfs is only used about 10-15gb of data, with iscsi it's around 80.