SYNOPSIS
--------
-**hail** [ **-t** *file* | **--simulate** *spec* ] [options...] *input-file*
+**hail** [ **-t** *file* | **\--simulate** *spec* ] [options...] *input-file*
-**hail** --version
+**hail** \--version
DESCRIPTION
-----------
response. In case of critical failures, the error message is printed
on stderr and the exit code is changed to show failure.
+If the input file name is ``-`` (a single minus sign), then the request
+data will be read from *stdin*.
+
ALGORITHM
~~~~~~~~~
pair; this is the only choice where the algorithm is non-trivial
with regard to cluster size.
+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 node changes (*change-node* mode), we currently support DRBD
instances only, and all three modes (primary changes, secondary changes
and all node changes).
is based on the same algorithm as allocations (group with lowest score
after placement).
-The deprecated *relocate* and *multi-evacuate* modes are no longer
-supported.
+The deprecated *multi-evacuate* modes is no longer supported.
In all cases, the cluster (or group) scoring is identical to the hbal
algorithm.
The options that can be passed to the program are as follows:
--p, --print-nodes
+-p, \--print-nodes
Prints the before and after node status, in a format designed to allow
the user to understand the node's most important parameters. See the
man page **htools**(1) for more details about this option.
--t *datafile*, --text-data=*datafile*
- The name of the file holding cluster information, to override the
- data in the JSON request itself. This is mostly used for debugging.
+-t *datafile*, \--text-data=*datafile*
+ The name of the file holding cluster information, to override the data
+ in the JSON request itself. This is mostly used for debugging. The
+ format of the file is described in the man page **htools**(1).
---simulate *description*
- Similar to the **-t** option, this allows overriding the cluster
- data with a simulated cluster. For details about the description,
- see the man page **hspace**(1).
+\--simulate *description*
+ Backend specification: similar to the **-t** option, this allows
+ overriding the cluster data with a simulated cluster. For details
+ about the description, see the man page **htools**(1).
--S *filename*, --save-cluster=*filename*
+-S *filename*, \--save-cluster=*filename*
If given, the state of the cluster before and the iallocator run is
saved to a file named *filename.pre-ialloc*, respectively
*filename.post-ialloc*. This allows re-feeding the cluster state to
- any of the htools utilities.
+ any of the htools utilities via the ``-t`` option.
-v
This option increases verbosity and can be used for debugging in order