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On 2006-07-10 15:54, silpa kala wrote:
Hi, Thanks for ur information.I need some more clarifications. What is the input of chunker ? why the chunker is necessary?
The input of the chunker is the backup data. Chunker writes this data to holdingdisk in small pieces. The main reason is that some filesystems cannot have files larger than 2 (or 4) Gigabyte. You may also have many holdingdisk, and chunker will write the chunks spread over the holdingdisk, not being limited by the size of one holdingdisk. In Amanda 2.4.5 and earlier, there was no "chunker" process: in those releases this feature was built in to dumper (see below).
what is the input of dumper ? what is the output of dumper?
For each backup, a "dumper" gets the instructions from driver to start that particular backup. There are many dumpers operating in parallel, each doing one disk-list-entry (DLE) at a time. The dumper is responsible to contact the client and get the backup started there. There is no real output of dumper, except the status of the backup when it is finished, which it communicates to driver. (So that driver can make an intellegent decision what to do next.) The purpose of a dumper program is to supervise the backup of one single disk-list-entry. Because Amanda starts many dumpers at once, there are many backups in progress at once too.
TCP ports are used to connect transfer the data.
(??I'm afraid I do not really understand "to connect transfer"...) Yes, the data is transferred using a TCP connection.
Whether which module is used for the socket connection at the client side?
(??What do you mean by "module"?) The server program "dumper" connects to the amanda UDP port 10080 and requests a "sendbackup". The server also sends a list of 2 or 3 TCP portnumbers containing the DATA, MESG (+error), and, if index was asked another one for the INDEX datastream. The client executes the correct handling program (for gnutar or for dump), making sure the stdout is connected to the DATA tcp port, and stderr is connected to the MESG tcp port and, if indexing is needed, the data-stream is actually duplicated with a tee-like mechanism, and fed in the gnutar/restore program with a table-of-contents option. The output of that stream is then connected to the tcp port that the server asked for the INDEX stream.
Suppose if the backup size more than 65535 bytes. How the client module will send the backup? whether the backup data is divided into more than one packet. Please clarify ?
This buffer size has nothing to do with the size of the backup. The send and receive buffer is a property of a TCP connection. (Phew! are you really sure you want to reorganize the socket code in Amanda?)
Thanks In advance.
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