search

NVSL / linux-nova

NOVA is a log-structured file system designed for byte-addressable non-volatile memories, developed at the University of California, San Diego.
http://nvsl.ucsd.edu/index.php?path=projects/nova
Other
421 stars 117 forks source link

Combine metadata_csum with replica_metadata #35

Closed stevenjswanson closed 7 years ago

stevenjswanson commented 7 years ago

They need to have the same value, so we should just have one flag.

luzh commented 7 years ago

Does it still make sense to have replica_metadata == 1 and metadata_csum == 0 so as to just handle media errors without checksum?

stevenjswanson commented 7 years ago

The only reason would be performance. Is csum expensive?

You can leave the flags in the code, but we should have a single command line option. Generally we should consolidate the commandline options, so there are fewer cases to test.

What do you think a good set of command line options would be? That is, what our actual users likely to actually want to do?

-steve

-- Composed on (and maybe dictated to) my phone.

On Jul 8, 2017, at 14:21, Lu Zhang notifications@github.com wrote:

Does it still make sense to have replica_metadata == 1 and metadata_csum == 0 so as to just handle media errors without checksum?

— You are receiving this because you authored the thread. Reply to this email directly, view it on GitHub https://github.com/NVSL/linux-nova/issues/35#issuecomment-313881751, or mute the thread https://github.com/notifications/unsubscribe-auth/AIpg3YgJSNwVlnSI4SexUO0CLmKFZgUPks5sL_LYgaJpZM4OR3d7 .

luzh commented 7 years ago

Checksum is cheap for metadata according to our evaluation (<10% perf cost according to our evaluation). I think for metadata a single option like 'metadata_prot' is the best, unless you think there are users that would like to have replicas alone.

luzh commented 7 years ago

Combined as one metadata_csum option: https://github.com/NVSL/linux-nova/commit/bd5d3ef8f98656a702f610f9bd4e47b8d9f09d26