diff options
Diffstat (limited to 'sbin/hastd/hastd.8')
-rw-r--r-- | sbin/hastd/hastd.8 | 36 |
1 files changed, 18 insertions, 18 deletions
diff --git a/sbin/hastd/hastd.8 b/sbin/hastd/hastd.8 index b614f36..017e895 100644 --- a/sbin/hastd/hastd.8 +++ b/sbin/hastd/hastd.8 @@ -70,18 +70,18 @@ hastd: <resource name> (<role>) .Pp If (and only if) .Nm -operates in primary role for the given resource, corresponding +operates in primary role for the given resource, a corresponding .Pa /dev/hast/<name> disk-like device (GEOM provider) is created. File systems and applications can use this provider to send I/O requests to. Every write, delete and flush operation .Dv ( BIO_WRITE , BIO_DELETE , BIO_FLUSH ) -is send to local component and replicated to the remote (secondary) node if it -is available. +is sent to the local component and replicated on the remote (secondary) node +if it is available. Read operations .Dv ( BIO_READ ) -are handled locally unless I/O error occurs or local version of the data +are handled locally unless an I/O error occurs or the local version of the data is not up-to-date yet (synchronization is in progress). .Pp The @@ -100,38 +100,38 @@ The connection between two .Nm daemons is always initiated from the one running as primary to the one running as secondary. -When primary +When the primary .Nm -is unable to connect or connection fails, it will try to re-establish -connection every few seconds. -Once connection is established, primary +is unable to connect or the connection fails, it will try to re-establish +the connection every few seconds. +Once the connection is established, the primary .Nm will synchronize every extent that was modified during connection outage to the secondary .Nm . .Pp -It is possible that in case of connection outage between the nodes +It is possible that in the case of a connection outage between the nodes the .Nm primary role for the given resource will be configured on both nodes. This in turn leads to incompatible data modifications. -Such condition is called split-brain and cannot be automatically +Such a condition is called a split-brain and cannot be automatically resolved by the .Nm -daemon as this will lead most likely to data corruption or lost of +daemon as this will lead most likely to data corruption or loss of important changes. Even though it cannot be fixed by .Nm -itself, it will be detected and further connection between independently +itself, it will be detected and a further connection between independently modified nodes will not be possible. -Once this situation is manually resolved by an administrator, resource +Once this situation is manually resolved by an administrator, the resource on one of the nodes can be initialized (erasing local data), which makes -connection to the remote node possible again. -Connection of freshly initialized component will trigger full resource +a connection to the remote node possible again. +Connection of the freshly initialized component will trigger full resource synchronization. .Pp -The +A .Nm -daemon itself never picks his role up automatically. +daemon never picks its role automatically. The role has to be configured with the .Xr hastctl 8 control utility by additional software like @@ -139,7 +139,7 @@ control utility by additional software like or .Nm heartbeat that can reliably manage role separation and switch secondary node to -primary role in case of original primary failure. +primary role in case of the primary's failure. .Pp The .Nm |