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August 27th, 2017 08:00
Compellent available space vs VMware available space
I am following best practice and provisioning my VM's as thick eager zero on my SC4020 and this keeps the available space out of sync between vmware and storage manager since compellent doesn't store white space and data progression dedupes and compresses the data. VMware will always show that more space is being consumed than actually is on the back-end storage. In order to use this saved space do I just need to create more datastores and essentially over-provision? My concern is if I thick eager zero all of the VM's in a datastore and they consume 2TB of a 2TB datastore from a VMware prospective, then will vmware complain and tell me I am out of space when trying to create snapshots or add additional VM's? In my example above, the SC4020 may be only using 1TB of the 2TB of space so in reality I have an extra TB available to use.
littlesteve
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August 29th, 2017 12:00
This is the best practice ->
As a best practice, use the default virtual disk format of thick provision lazy zeroed unless there are specific needs to pre-allocate virtual disk storage such as Microsoft clustering, VMware Fault Tolerance (FT), or for virtual machines that may be impacted by the thin or zeroedthick on-first-write penalties. If the application is sensitive to VMFS write penalties, it is recommended to test eagerzeroedthick virtual disks to determine the actual performance impact.
And you should consider this from a SC point of view->
SC Series thin write functionality:
Most versions of SCOS have the ability to detect incoming sequential zeroes while being written and track them, but not actually write the zeroed page to the physical disks. When creating virtual disks on these versions of firmware, all virtual disk formats will be thin provisioned at the array level, including thick provision eager zeroed.
Look at this doc also -> Understanding RAID with Dell SC Series Storage - White Papers ...