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From Mike Matrigali <mikem_...@sbcglobal.net>
Subject Re: Memory-only mode and transactions/locking
Date Wed, 13 Apr 2005 17:10:37 GMT
Another hardware option that can help derby out a lot is placing
the log file on a battery backed disk or even cheaper is to get
a controller with a battery backed frontend cache.  I have seen
results on the latter and it basically removes the log sync I/O
bottle neck for a number of commit bound applications with no
change necessary to the application.  The cache does not have to
be that big as it just needs to caches the I/O from the log
commit long enough for it to hit disk before the cache fills.

I don't get much server hardware to play with any more, but the
last machine we got had it as a default configuration (it took
us awhile to figure out why our numbers were so good :-) ).


David Van Couvering wrote:
> I have on my "like to do" plate the following:
> - build a prototype in-memory store for Derby
> - do some performance tests of this compared to running Derby with a 
> *massive* JVM cache and Derby cache and RAMdisk for disk storage.  A lot 
> of machines put /tmp on RAM, you don't even need to purchase special 
> software.
> - See how they compare...
> David
> Kevin Foster wrote:
>> Elissa Newman wrote:
>>  > Does Derby have a mode such that it runs in memory only? I am 
>> working on
>>  > a project that needs the database to run in memory and not go to the
>>  > disk at all (the amount of memory we have for our system should 
>> suffice
>>  > for the database size we will have). I reviewed the available
>>  > documentation and did not see a setting for something like this.
>> Has anyone tried Derby on a RAM Disk? Here's an example (Google search 
>> on "ramdisk"):
>>     http://www.superspeed.com/ramdisk.html
>> It obviously wouldn't be a safe place to keep data in case of machine 
>> failure, but if safety isn't a requirement, then I would guess that 
>> performance would improve accordingly. Maybe not to the theoretical 
>> maximum speed possible without logging, but memory is a lot faster 
>> than a physical disk would be.
>> -Kevin

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