Hi, all:
I have two questions about MDLog:
1. The max number of logsegments per MDlog (mds_log_max_segments) is configured
to be 30 in the config_opts.h file.
However, the MDLog doesn’t check the number of logsegments when it start a new
segment.
The configuration is only used when the number of segments in a MDLog is larger
than 2*mds_log_max_segments.
The MDS notifies monitor, while the monitor does nothing.
My question is: Is the logsegments size limited to a max size? If so, what’s
the size?
2. The MDLog prezeros two periods ahead of the write_pos of Journaler.
The comment of _issue_prezero function is “we need to zero at least two
periods, minimum, to ensure that we have a full empty object/period in front of
us”.
Does it means that the OSD will preallocate objects for the Journaler ?
The function is actually implemented by Objecter::remove. However, the
Objecter::remove only removes a object through FileStore/NewStore.
It seams that the OSD doesn’t preallocate objects. If so, then what’s the
purpose of prezero? Or, do I misunderstand anything?
Thanks.
Best regard,
Fei Xia
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