From: Kern S. <ke...@si...> - 2005-01-29 22:07:26
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Hello, On Mon, 2005-01-17 at 15:37 +0100, Ludovic Drolez wrote: > Hello, > > I'd like to add a RAIT feature in the storage daemon: each data block would be > divided in 3 or 4 blocks (+ a checksum block), which would be sent to X tape > devices in parallel. > > For that I'd like to have to confirmation that *all* data writes or reads end up > in write_block_to_dev() or read_block_from_dev() (including label writings). This is correct up to version 1.37.2. However, in version 1.37.3, if you have ANSI or IBM labels turned on, the ANSI/IBM label will be read/written in label.c. Each ANSI/IBM label consists of 3 80 character records (read or writes). > > Also Bacula would need to send fixed size blocks (for example, Minimum Block > Size = Maximum Block Size = X tapes * 32k ). Does it add more limitations to > bacula ? Using Minimum/Maximum block sizes doesn't necessarily "limit" Bacula. In the normal operation (non-RAIT), it is not recommended. The only major downsize of fixed block sizes is that a bit of space is wasted on tapes to occasionally pad to the fixed size. If you are planning to submit code for integration into Bacula, I would recommend that you provide us a general overview of what you are planning and a good amount of detail on the modifications necessary to Bacula. Please do this before you begin so that there are misunderstandings. Recently someone submitted some code representing a fair amount of work, and it was not accepted for a number of reasons. I would like to avoid such situations ... -- Best regards, Kern |