Bluestore Internals

## Bluesotre Discussions
If WAL is full what would happen? Would writes block?

It never blocks; it will always just spill over onto the next fastest
device (wal -> db -> main). Note that there is no value to a db partition
if it is on the same device as the main partition.

Would a drastic (quick) action to correct a too-small-DB-partition
(impacting performance) is to destroy the OSD and rebuild it with a
larger DB partition?

I would check your running Ceph clusters and calculate the amount of objects per OSD.
total objects / num osd * 3

For the moment though, having multiple (4)
256MB WAL buffers appears to give us the best performance despite
resulting in large memtables, so 1-2GB for the WAL is right.

A tool to gather complete Ceph cluster information

Bluesotre onode size is 24k for average object size of 2.8MB in RBD. So average object size and count per TB can be calculated.


Written with StackEdit.

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