From: Ivan Mikhailov <[email protected]> Cc: [email protected], Alan Ruttenberg <[email protected]> Date: Thu, 13 May 2010 12:45:49 +0700
Hello Alan, That's normal behavior and it is described in http://docs.openlinksw.com/virtuoso/CHECKPOINT.html#checkpointparams with all related configuration details. I've read that page before, but I don't see how it applies exactly. There are two configuration parameters mentioned: UnremapQuota and MaxCheckpointRemap. UnremapQuota is new to me, doesn't occur in my virtuoso.ini, and isn't described in your configuration file documentation (at http://docs.openlinksw.com/virtuoso/dbadm.html). I don't know what its default value is. MaxCheckpointRemap I had set to 250000. Are you telling me that this causes me to waste 26G of space? 250000 pages should be something like 2G, so how do I get from there to 26G? But OK, the page you sent me to does say that: "Setting the maximum checkpoint remap to zero in such a situation causes the next checkpoint to unremap all checkpoint remapped pages, restoring physical sequence and freeing disk space." So I set MaxCheckpointRemap to 0, restarted Virtuoso, manually invoked a checkpoint, and even did another dump and restore, but I've still got a 67G database and Conductor tells me I have 26G "free". So exactly what steps do I have to take to get this database to occuly less space on disk? Or is it hopeless and I should just ignore conductor when it tantalizingly tells me there is 25G "free" in my database? I have little experience in maintaining these issues because all my big databases are for debugging purposes and the disk space is freed by deleting them ;) Best Regards, Ivan Mikhailov OpenLink Software http://virtuoso.openlinksw.com On Wed, 2010-05-12 at 20:00 -0400, Alan Bawden wrote: > Using Virtuoso 6.1.1, I loaded a database containing about 500 million > triples (and a fair amount of text). After loading, the on-disk database > had expanded to about 67G of storage. Conductor reported that I had about > 26G -free- in that database. (I'm not sure exactly why that extra space > was needed during the load, but it is perhaps the result of a computation > we run as part of loading that creates and drops a number of temporary > graphs.) > > Since it would be handy to recover that 26G of disk space for other > purposes, I did a full backup followed by a restore into a fresh Virtuoso. > I was suprised to find that the restored database was still 67G on disk > with 26G of free space. I seem to recall using backup/restore to reclaim > free space several releases ago, and it worked. Is my memory failing me? > > In any case, is there any way to get Virtuoso to let me have those 26G > back? Or is that space not "free" in that sense of the word? > > (I went looking for tools that claimed to be able to "clean up" the > database in any sense, but the only thing I found was DB.DBA.VACUUM(), > which does not help.) >
