Solved: vSphere 5.5 - Shared Value for VM

Najkon · ‎08-22-2018

HI,

Do it's possible to make Unlimited Shared Value for each VM?

I want to achieve in this way fast access to disks write/read

at this moment I have Shared Value set to 4000 and IOPs limit to Unlimited. Cannot set more that 4000 Shared Value (error popup from Client View say it must be between 200 a 4000.

Simple test write on Linux VM:

dd if=/dev/zero of=/mnt/trash/test-file bs=999k count=10k; rm /mnt/trash/test-file
10240+0 readed records
10240+0 writed records
10475274240 bytes (10 GB, 9,8 GiB) copied, 794,036 s, 13,2 MB/s

In that same machine with that same configuration (hw and soft) but without virtualize - system copied 1:1

dd if=/dev/zero of=/mnt/trash/test-file bs=999k count=10k; rm /mnt/trash/test-file

10240+0 readed records
10240+0 writed records
10475274240 bytes (10 GB, 9,8 GiB) copied, 22,18s, 472 MB/s

It's a HUGE difference - how to change it?

Najkon · ‎08-25-2018

I find the problem..

it turned out to be a hardware controller and Cache Ratio setting. In my case it was HP P410 Hw Controller

/opt/smartstorageadmin/ssacli/bin/ssacli ctrl all show config detail | head -40

Cache Board Present: True
Cache Status: OK
Cache Status Details: A cache error was detected. Run a diagnostic report for more information.
Cache Ratio: 100% Read / 0% Write
Drive Write Cache: Disabled

to fix it, the Cache Ratio must be forced by 50/50

/opt/smartstorageadmin/ssacli/bin/ssacli ctrl slot=2 modify cr=50/50 forced

and then suddenly the error disappears, and we can change it to the optimal setting for us.. for example 25 % Read / 75% Write

/opt/smartstorageadmin/ssacli/bin/ssacli ctrl slot=2 modify cr=25/75
/opt/smartstorageadmin/ssacli/bin/ssacli ctrl all show config detail | head -40

Smart Array P410 in Slot 2
   Bus Interface: PCI
   Slot: 2
[....]
   Cache Board Present: True
   Cache Status: OK
   Cache Ratio: 25% Read / 75% Write
   Drive Write Cache: Enabled
   Total Cache Size: 256 MB
   Total Cache Memory Available: 144 MB

dd if=/dev/zero of=/mnt/trash/test-file bs=999k count=10k; rm /mnt/trash/test-file
10240+0 readed records
10240+0 writed records
10475274240 bytes (10 GB, 9,8 GiB) copied, 27,8135 s, 377 MB/s

And everything works!

View solution in original post

Najkon · ‎08-25-2018