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The purpose of this shootout was to analyze already backed up images of VM guests sitting idle on disk. We like to keep 7 days online, so I was curious as to how the two compared in our environment.

Compressed vs Deduplicated

COMPRESSED: (backed up via vRanger Pro over VCB, size on win NTFS volume)
citrix_server = 4.29gb
win_sql_server_64bit = 9.76gb
citrix_server2 = 6.14gb
win2k3_member = 4.97gb

compressed vm total = 25.16gb

UNCOMPRESSED:

citrix_server = 10gb
win_sql_server_64bit = 20gb
citrix_server2 = 10gb
win2k3_member = 35gb

uncompressed total = 75gb

DEDUPED VS COMPRESSED:

deduped     = 54.29% savings (NetApp cmd output below)
compressed     = 66.45% savings

Here’s the actual output from the NetApp find_space exe:
A-SIS Deduplication Space Savings estimate.

Name of Fingerprint File:          d:\esx_deduped.txt
Total Number of Directories:       5
Total Number of Files:             58
Total Number of 4K Blocks:         19662390
Total Number of Duplicate Blocks:  10673928
Percentage of Duplicate Data:      54.29
Scan Start Time:                   Wed, Jul 30 2008 3:40:16 PM
Scan End Time:                     Wed, Jul 30 2008 4:22:25 PM

I’ll be honest, I was expecting deduplication to blow compression out of the water even with only 4 vm’s. I’ll go out on a limb and venture that deduplication would provide more results as you toss more vm’s into the picture.

I’ve been doing a little testing with NetApp Deduplication lately but only in a limited test environment.  I know one thing for certain, deduplication and compression do not mix at all!  When you start to look at this technology make sure you’re dealing with uncompressed data.  This posting is more or less a bookmark for:

“Scott’s Quick Guide to Setting up Netapp Deduplication”

NetApp does provide a useful windows exe called “find_space” which you can run in report mode against any windows data volume.

I came into work this morning and one of the ESX hosts had HA disabled.  The network engineers replaced the core switch and I have to assume the NIC connectivity caused HA to disable since they were all down at once.  One command helped me get HA enabled:

SSH to the host that is disabled and as root execute:

service mgmt-vmware restart

Then enable HA after successfully running the command.