Changes between Version 2 and Version 3 of HostId

Timestamp:

Oct 24, 2007, 10:57:38 AM (17 years ago)

Author:

davea

Comment:

--

HostId

@@ -1 @@
-= Host identification =
+= Computer identification =
 
-== Host identification ==
-Not all systems have an application-readable globally unique IDs, so we use a different approach to host identification. When a host first contacts the scheduling server it is assigned a host ID. The server also maintains an RPC sequence number for each host. Both the host Id and the RPC sequence number are stored in the client's `client_state.xml` file.
+== How computers are identified ==
 
-If the scheduling server receives an RPC with a sequence number less than the expected sequence number, it creates a new host record in the database. (This might happen, for example, if a user copies the `client_state.xml` file between hosts.)
+We haven't found a universal hardware-level mechanism (CPU chip ID, MAC address)
+for uniquely identifying computers.
+So we do it in software as follows:
+When a computer first contacts a project's scheduling server,
+the server creates a database record for the computer ,
+which includes a host ID and an RPC sequence number.
+The computer ID and the RPC sequence number are also stored in the client's `client_state.xml` file.
+The client increments the RPC sequence number on each scheduler request.
 
+If the scheduling server receives an RPC with a sequence number less than the expected sequence number
+(usually indicating that the user has copied the `client_state.xml` file between computers)
+it creates a new database record and returns a new ID.
 
-== Merging duplicate host records ==
-This mechanism can lead to situations where the server has multiple host records for a single host. For example, this will occur if the user deletes the `client_state.xml` file.
+== Merging duplicate computer records ==
 
-The user can merge these duplicates to a single record using the '''Merge hosts''' command on the web interface.
+This mechanism can lead to situations where a project's server has multiple database records for a single computer.
+For example, this will occur if the user deletes the `client_state.xml` file.
+The user can merge these duplicates into a single record via a web interface.
 
+You may only merge two computer records if
+ * They have the same processor type (Intel, AMD etc.) and operating system.
+ * They don't overlap in time; i.e. computer 1's last RPC happened before computer 2's first RPC, or vice-versa.
+
+There are two ways of merging computer records:
+
+ * To merge a single computer, open its Summary page, and click on "Merge this computer".  You will see a list of computers eligible to be merged with this one, and you can select any or all of them.
+ * The "Your computers" page has a link '''Merge computers by name'''.  This feature lets you automatically merge all eligible computers having the same domain name.  This is handy if you run a "computer farm" and periodically reformat all the drives.