Commit 5b53ca79 authored by Iustin Pop's avatar Iustin Pop
Browse files

htools: update hail man page with the new modes

Also mark the deprecated modes we no longer support.
Signed-off-by: default avatarIustin Pop <>
Reviewed-by: default avatarMichael Hanselmann <>
parent 1b0a6356
......@@ -16,9 +16,8 @@ SYNOPSIS
hail is a Ganeti IAllocator plugin that allows automatic instance
placement and automatic instance secondary node replacement using the
same algorithm as **hbal**(1).
hail is a Ganeti IAllocator plugin that implements the instance
placement and movement using the same algorithm as **hbal**(1).
The program takes input via a JSON-file containing current cluster
state and the request details, and output (on stdout) a JSON-formatted
......@@ -30,10 +29,6 @@ ALGORITHM
The program uses a simplified version of the hbal algorithm.
For relocations, we try to change the secondary node of the instance
to all the valid other nodes; the node which results in the best
cluster score is chosen.
For single-node allocations (non-mirrored instances), again we
select the node which, when chosen as the primary node, gives the best
......@@ -42,11 +37,22 @@ For dual-node allocations (mirrored instances), we chose the best
pair; this is the only choice where the algorithm is non-trivial
with regard to cluster size.
For node evacuations (*multi-evacuate* mode), we iterate over all
instances which live as secondaries on those nodes and try to relocate
them using the single-instance relocation algorithm.
For node changes (*change-node* mode), we currently support DRBD
instances only, and all three modes (primary changes, secondary changes
and all node changes).
For group moves (*change-group* mode), again only DRBD is supported, and
we compute the correct sequence that will result in a group change; job
failure mid-way will result in a split instance. The choice of node(s)
on the target group is based on the group score, and the choice of group
is based on the same algorithm as allocations (group with lowest score
after placement).
The deprecated *relocate* and *multi-evacuate* modes are no longer
In all cases, the cluster scoring is identical to the hbal algorithm.
In all cases, the cluster (or group) scoring is identical to the hbal
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