Awesome post: VMFS Details
Friday, 13 March 2009 00:20

Tonight I was reading the Planet V12n list, looking for new interesting articles. Now one spotted my eye which is very cool. Mike La Spina has written detailed info about the VMFS. Read the full article here. Now the thing I really like was the part for 'backing-up' your VMFS. I quote:

"

For example we create a new VMFS store on the same storage backing with the same LUN size as the original and it shows up as a LUN with a device name of /dev/sdd we can use esxcfg-vmhbadevs -m to find it if required

The deleted device name was /dev/sdc

We use the dd command to do a block copy from the new partition to a file or even directly in this case.

Remember to back it up first!

dd if=/dev/sdc of=/var/log/part-backup-sdc-1st.hex  bs=512 count=1

then issue

dd if=/dev/sdd of=/dev/sdc bs=512 count=1

or 

dd if=/dev/sdd of=/var/log/part-backup-sdd.hex bs=512 count=1

dd if=/var/log/part-backup-sdd.hex of=/dev/sdc bs=512 count=1

"

Very nice!

And also:"

As as an additional level of protection we could even include making backups of the vh.sf metadata file and the VMFS header.

cp /vmfs/volumes/49716cd8-ebcbbf9a-6792-000d60d46e2e/.vh.sf /var/log/vh.sf.bu

dd if=/dev/sdc of=/var/log/vmfsheader-bu-sdc.hex bs=512 count=4096

This would grant the ability for support to examine the exact details of the VMFS configuration and potentially allow recovery from more complex issues.

"

This one is going into my default actions list when deploying at customers... Put it on memory stick as a backup Cool! Many thanks Mike La Spina!

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Did you know: that ESX checks every 20ms to migrate a vCPU to another pCPU for the optimal workload balance. This is configurable (0ms - 5000ms) in Cpu.MigratePeriod in Advanced Settings of you ESX server.