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From Mike Matrigali <mikem_...@sbcglobal.net>
Subject Re: [jira] Commented: (DERBY-239) Need a online backup feature that does not block update operations when online backup is in progress.
Date Mon, 31 Oct 2005 21:14:53 GMT

windows allows one to partition in software, I think included in the 
base OS.  Can someone say if linux does or not (or at least a particular
version of linux).  I do agree that hardware can do a more efficient
job than software.

I am not sure how expensive a RAID controller is to anyone who actually
needs multiple disks for performance of their app, I know my < $500
personal home machine came with it.

I believe Derby gives the OS plenty of opportunity to do parallel I/O
if there are multiple users in the database.  Every thread can possibly
be doing I/O at a single time.  There may be room to improve in the case
of checkpoint, but not sure how important that is.

I agree that single user Derby does not do parallel.
Øystein Grøvlen wrote:
>>>>>>"MM" == Mike Matrigali <mikem_app@sbcglobal.net> writes:
>     MM> Yes this is probably incorrect in a number of places.  There currently
>     MM> is only one segment.  The segment number was added in the beginning so
>     MM> that if we ever had to  do data partitioning ourselves we had a chance
>     MM> to
>     MM> add it without an ugly upgrade.  But as you are seeing over time some
>     MM> hard coding has happened and if we ever really want another segment it
>     MM> will have to be cleaned up.
>     MM> My opinion is that the OS can do better data partitioning then we can so
>     MM> I don't think it is very useful to add that feature.
> I agree that the OS often can do a better job with data partitioning
> but that often requires expensive storage systems (e.g., RAID).  
> I think that many applications would perform better if it was possible
> to put tables and indexes on different disks.
> Also, Derby does not give the OS much opportunity to optimize IO as
> long as it does not allow parallel disk accesses to a table.

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