[Xapian-discuss] Xapian on SSD vs SATA

[Henry]

Greets,

Either Xapian is not as IO intensive as I always thought, or I'm  
missing something.

I've been running some tests to assess how many search nodes I'll need  
for a nnnGB index to ensure ~1s search query performance.

The idea was to reduce the number of nodes needed using SSDs (since  
the performance gains (eg) on an IO intensive DB are staggering)  
versus the number needed using standard SATA disks (ie, larger index  
on SSDs using less nodes, versus smaller indexes on more nodes using  
slower SATA hard drives).

Anyway, the results are disappointing.  The SSD provides no  
appreciable performance gain at all (aside:  the SSD was using ext2  
since it was also used to test a DB app, which didn't need the  
journalling overhead of ext3 - this might explain the .10 - .80 second  
average *slower* performance of the SSD).

My gut is that Xapian is more sequential-read intensive (not random  
IO) which would explain this disappointing result.  Am I right?

Cheers
Henry