VMware performance: physical partitions vs images?

[Kurt Granroth]

Technomage wrote:
> I am an experienced user of vmware products (both the server and workstation 
> lines). using real partitions is definitely gives better performance over 
> using "loop back image" partitions.
> 
> This situation is most noticeable when using only 128 MB of ram for the vmware 
> instance and reserving the other 128 for the host system (which is what I run 
> mac OS Darwin under here).. running the guest system "natively" is definitely 
> far superior, but failing that, running a vmware guest OS using real hardware 
> is 30-50% faster than via loopback.

That's what I would have guessed, too.  I just did some random
benchmarks, though, and now I'm not so sure.  I ran 'bonnie++',
'dbench', and then did a few things with tar files.

'dbench' measure throughput for multiple clients.  Bonnie++ measures
quite a few things.  The tar tests each tested different things, which
are noted below.  I attached the Bonnie++ HTML output which is easier to
look at.

I ran the tests within VMware on a (pre-allocated) vmware image, a
physical partition, and on then on the Host system on the same physical
partition.  The most notable result of the tests is how similar they all
are!  I was expecting the physical partition to run away with the tests
but that wasn't the case at all.

dbench: pretty much the same
bonnie++: images are FASTER for writing and roughly the same otherwise
tar: extracting the tar file is as fast on the image as on the host
system and weird results for the raw access.  images were notably slower
while creating a tar file made up of 45,000 files.  in all other cases,
they were close enough not to notice in "real life"

So all in all, my tests *seem* to indicate that images are far faster
than we all thought!


System
======================================================================
Host: 2.8Ghz P4, SATA WDC WD1600JD-75H UDMA/133, 1GB RAM
      VMware Server 1.01
      SuSE 9.3
      /dev/sda10 -> 12G; WIN32; 11G Pre-allocated VMware image
      /dev/sda11 -> 12G; Reiser; Physical VMware access
Guest: 384MB RAM
       SUSE 10.1
       /dev/sda -> 8G; reiserfs; vmware image
       /dev/sdb -> 11G; reiserfs; image (host: /dev/sda10)
       /dev/sdc -> 12G; reiserfs; raw partition (host: /dev/sda11)

dbench 5
======================================================================
image: 133.9 MB/sec
raw  : 130.1 MB/sec
host : 134.2 MB/sec

bonnie++ -u 0:0
======================================================================
image,1G,35118,58,32685,18,11361,9,16324,25,13846,6,75.0,0,16,17522,99,+++++,+++,15117,97,17406,99,+++++,+++,15233,100
raw,1G,21187,55,27171,14,10113,6,16965,23,18265,6,100.1,1,16,17487,99,+++++,+++,15975,99,16970,99,+++++,+++,14689,99
host,2G,25702,31,24746,10,10937,3,17834,17,17309,2,104.5,0,16,22203,95,+++++,+++,19243,99,22791,99,+++++,+++,18199,99

Extract tar file (883MB; 45,386 files)
Purpose: Read large file; write thousands of little files
======================================================================
image: 1m32s
raw  : 2m06s
host : 1m29s

Create tar file (883MB; 45,386 files)
Purpose: Read thousands of little files; write one large file
======================================================================
image: 2m25s
raw  : 1m42s
host : 1m39s

cat 883MB > /dev/null
Purpose: Read large file by itself
======================================================================
image: 55.5s
raw  : 48.8s
host : 29.8s

cat 883MB 883MB > 1.7GB
Purpose: Read large file; write to very large file
======================================================================
image: 2m19s
raw  : 2m50s
host : 2m02s
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