Class TLReplaceDisks

Check prerequisites, second part.

This function should always be part of CheckPrereq. It was separated and is now called from Exec because during node evacuation iallocator was only called with an unmodified cluster model, not taking planned changes into account.

Create new storage on the primary or secondary node.

This is only used for same-node replaces, not for changing the secondary node, hence we don't want to modify the existing disk.

Replace a disk on the primary or secondary for DRBD 8.

The algorithm for replace is quite complicated:

1. for each disk to be replaced:
   1. create new LVs on the target node with unique names
   1. detach old LVs from the drbd device
   1. rename old LVs to name_replaced.<time_t>
   1. rename new LVs to old LVs
   1. attach the new LVs (with the old names now) to the drbd device

1. wait for sync across all devices

1. for each modified disk:
   1. remove old LVs (which have the name name_replaces.<time_t>)

Failures are not very well handled.

Replace the secondary node for DRBD 8.

The algorithm for replace is quite complicated:

• for all disks of the instance:
  • create new LVs on the new node with same names
  • shutdown the drbd device on the old secondary
  • disconnect the drbd network on the primary
  • create the drbd device on the new secondary
  • network attach the drbd on the primary, using an artifice: the drbd code for Attach() will connect to the network if it finds a device which is connected to the good local disks but not network enabled
• wait for sync across all devices
• remove all disks from the old secondary

Failures are not very well handled.