• More than 53,000 VCP certifications have been issued worldwide across all versions!

• There are more than 15,000 VCP4 holders worldwide!

Pretty impressive since the VCP4 certification is only 6 months old.



For now use the PVSCSI for virtual disks with more than 2000 iops.

I was just playing around with CPU reservations in vCenter. I wanted to verify that it actually works. I have been playing around with limits and shares a lot but never really tested cpu reservations.

The server I tested it on is a Intel Xeon E5410 (quad core 2,33ghz). I created 8 virtual machines and started the cpubusy.vbs we use on the vmware courses. At first I started out with no reservations for any of the machines.

Test 1: No reservations (Every VM is equal and results are what I expect)
_________________________________%USED                                %RDY
38     38 frped-1             4   48.51   48.78    0.01  300.05   52.32    0.00    0.24    0.00    0.00    0.00
39     39 frped-2             4   47.55   47.62    0.06  300.14   53.40    0.00    0.20    0.00    0.00    0.00
40     40 frped-3             4   46.83   46.98    0.00  299.84   54.33    0.00    0.15    0.00    0.00    0.00
41     41 frped-4             4   49.25   49.37    0.01  300.02   51.76    0.00    0.14    0.00    0.00    0.00
42     42 frped-5             4   47.80   47.91    0.01  299.84   53.40    0.00    0.13    0.00    0.00    0.00
43     43 frped-7             4   47.63   47.81    0.00  299.82   53.55    0.00    0.18    0.00    0.00    0.00
44     44 frped-6             4   48.32   48.47    0.01  300.03   52.68    0.00    0.16    0.00    0.00    0.00
45     45 frped-8             4   48.17   48.36    0.01  300.29   52.54    0.00    0.20    0.00    0.00    0.00

Test 2: Reservation 2400 mhz on frped-1 (Nothing happens?)
________________________________%USED                                %RDY
38     38 frped-1             4   47.81   48.02    0.00  299.75   52.80    0.00    0.17    0.00    0.00    0.00
39     39 frped-2             4   48.41   48.68    0.01  299.29   52.60    0.00    0.20    0.00    0.00    0.00
40     40 frped-3             4   48.00   48.10    0.01  299.25   53.21    0.00    0.13    0.00    0.00    0.00
41     41 frped-4             4   47.58   47.68    0.01  299.48   53.41    0.00    0.14    0.00    0.00    0.00
42     42 frped-5             4   46.91   47.05    0.00  299.23   54.30    0.00    0.14    0.00    0.00    0.00
43     43 frped-7             4   47.93   48.06    0.00  299.64   52.87    0.00    0.14    0.00    0.00    0.00
44     44 frped-6             4   48.35   48.69    0.01  298.62   53.26    0.00    0.33    0.00    0.00    0.00
45     45 frped-8             4   48.06   48.34    0.00  299.61   52.62    0.00    0.18    0.00    0.00    0.00

Test 3: Reservation 2300 mhz on frped-1 (WORKS)
________________________________%USED                                %RDY
38     38 frped-1             4   97.74   97.70    0.01  298.35    2.90    0.00    0.19    0.00    0.00    0.00
39     39 frped-2             4   39.89   40.07    0.00  298.08   60.78    0.00    0.20    0.00    0.00    0.00
40     40 frped-3             4   41.02   41.17    0.00  297.84   59.95    0.00    0.15    0.00    0.00    0.00
41     41 frped-4             4   39.96   40.11    0.01  297.95   60.90    0.00    0.14    0.00    0.00    0.00
42     42 frped-5             4   42.34   42.44    0.01  298.42   58.12    0.00    0.14    0.00    0.00    0.00
43     43 frped-7             4   42.40   42.56    0.00  298.47   57.95    0.00    0.17    0.00    0.00    0.00
44     44 frped-6             4   39.85   40.20    0.00  297.78   60.99    0.00    0.13    0.00    0.00    0.00
45     45 frped-8             4   41.18   41.18    0.00  297.50   60.29    0.00    0.21    0.00    0.00    0.00

With vShpere a new PVISCSI virtual disk controller has been introduced. The new controller is good for high IO intensive virtual machines. What is new (at least for me) is that it is better to use the LSI Logic controller for low-io workloads.

The KB states you should use the PVISCSI for vm’s with more than 2000 IOPS! That is a lot of IOPS, so just continue on using the LSI for most of your workloads.

• PVSCSI is best for workloads that drive more than 2000 IOPS and 8 outstanding I/Os.
• LSI Logic is best for workloads that drive lower I/O rates and fewer outstanding I/Os.

Ever since ESX3.0 we have used the VMFS3 filesystem and we are still using it on vShpere. What most people don’t know is that there actually is sub versions of the VMFS.

• ESX 3.0 VMFS 3.21
• ESX 3.5 VMFS 3.31 key new feature: optimistic locking
• ESX 4.0 VMFS 3.33 key new feature: optimistic IO

The good thing about it is that you can use all features on all versions. In ESX4 thin provisioning was introduced but it does need the VMFS to be 3.33. It will still work on 3.21.

The changes in the VMFS is primarily regarding the handling of SCSI reservations. SCSI reservations happens a lot of times. Creation of new vm, growing a snapshot delta file or growing thin provisioned disk etc. (KB1005009)

If you have started out with vShpere all of your VMFS will be 3.33. Then there is really nothing to think about. But if you have been running ESX3 and upgrading your hosts to 3.5 and later 4.0 there is a good chance your VMFS is at 3.21. If that is the case I would recommend you to upgrade your VMFS to the newest version. So how do you upgrade? Either cold migrate or storage vmotion all virtual machines and templates away from a datastore. When the datastore is empty delete it and create it again.

So how do you find out what version your VMFS is running? Simple, you can see this information from the vShpere client. Go to Configuration – Storage and select a datastore. Then look in the datastore details: