Specifying target size using the absolute size of the pool

Specify the target size of a pool by using the absolute size of the pool.

Set the target size using the absolute size of the pool in bytes:
```
 ceph osd pool set pool-name target_size_bytes value
```
For example, to instruct the system that mypool is expected to consume 100T of space:
```
 $ ceph osd pool set mypool target_size_bytes 100T
```

You can also set the target size of a pool at creation time by adding the optional --target-size-bytes <bytes> argument to the ceph osd pool create command.