Reweights the OSD temporarily.

    Note that ‘ceph osd reweight’ is not a persistent setting. When an OSD
    gets marked out, the osd weight will be set to 0. When it gets marked
    in again, the weight will be changed to 1.

    Because of this ‘ceph osd reweight’ is a temporary solution. You should
    only use it to keep your cluster running while you’re ordering more
    hardware.

    - Craig Lewis (http://lists.ceph.com/pipermail/ceph-users-ceph.com/2014-June/040967.html)