Look likes a good plan (if you have time enough to do all you suggest).
In case your aiming for a certain recovery time, it would be good
to run experiments to evaluate how accurate your estimates are. I.e.,
how long does the recovery actually take.
--
Øystein
Raymond Raymond wrote:
Thanks for so many people gave their suggestions on this issue.
I really learned a lot of things from it. Since I am doing a student
project
on derby, I am thinking of implementing two versions of checkpointing:
1. Let me call it "automaticaly scheduled checkpointing". In this version,
I will not change lots on the checkpointing mechanism. I will add a module
to schedule the checkpointing automaticaly depends on the system
performance what we have discussed before( e.p. recovery speed,
current disk I/O situation).The only thing I will change on the
checkpointing process is to make it wirte out several pages and sleep
for a while if the system is busy, and then write several more,and so on.
2. Let me call it "Incremental checkpointing"(details please refer to the
former discussions).
Then I want do some test and comparison among:
-- The current checkpointing mechanism
-- The automatically scheduled checkpointing mechanism
-- The incremental checkpointing mechanism
and we can know which one would be better.
I still have a questions about derby checkpointing. Someone can
help me to make it clear? ^_^.
I want to summarize what events will trigger a checkpoint?
On the derby website :
http://db.apache.org/derby/papers/logformats.html
I found such comments:
-------------------------------------------------------------------------------------------------------------------------------------------
With the default values, a new log file is created (this is known as log
switch) when a log file grows beyond 1MB and a checkpoint happens when
the amount of log written is 10MB or more from the last checkpoint.
RawStore exposes a checkpoint method which clients can call, or a
checkpoint is taken automatically by the RawStore when:
1. The log file grows beyond a certain size (configurable, default 1MB)
2. RawStore is shutdown and a checkpoint hasn't been done "for a while"
3. RawStore is recovered and a checkpoint hasn't been done "for a while"
-------------------------------------------------------------------------------------------------------------------------------------------
I am no very clear about what " for a while " means in the second and
the third comments.
I also want to know is there any other events will trigger a checkpoint
besides these?
Thanks.
Raymond
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