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6.2.3. Ordered Resource Sets
A common situation is for an administrator to create a chain of ordered resources, where, for example, resource A starts before resource B which starts before resource C. If your configuration requires that you create a set of resources that is colocated and started in order, you can configure a resource group that contains those resources, as described in Section 5.5, “Resource Groups”. If, however, you need to configure resources to start in order and the resources are not necessarily colocated, you can create an order constraint on a set or sets of resources with the
pcs constraint order set
command.
You can set the following options for a set of resources with the
pcs constraint order set
command.
sequential
, which can be set totrue
orfalse
to indicate whether the set of resources must be ordered relative to each other.Settingsequential
tofalse
allows a set to be ordered relative to other sets in the ordering constraint, without its members being ordered relative to each other. Therefore, this option makes sense only if multiple sets are listed in the constraint; otherwise, the constraint has no effect.require-all
, which can be set totrue
orfalse
to indicate whether all of the resources in the set must be active before continuing. Settingrequire-all
tofalse
means that only one resource in the set needs to be started before continuing on to the next set. Settingrequire-all
tofalse
has no effect unless used in conjunction with unordered sets, which are sets for whichsequential
is set tofalse
.action
, which can be set tostart
,promote
,demote
orstop
, as described in Table 6.2, “Properties of an Order Constraint”.
You can set the following constraint options for a set of resources following the
setoptions
parameter of the pcs constraint order set
command.
id
, to provide a name for the constraint you are defining.score
, to indicate the degree of preference for this constraint. For information on this option, see Table 6.3, “Properties of a Colocation Constraint”.
pcs constraint order set resource1 resource2 [resourceN]... [options] [set resourceX resourceY ... [options]] [setoptions [constraint_options]]
If you have three resources named
D1
, D2
, and D3
, the following command configures them as an ordered resource set.
# pcs constraint order set D1 D2 D3