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What will happen if unused disk space is fully utilized in Dell EMC ScaleIO
I have implemented 3 Node Dell EMC ScaleIO. Total capacity is of 8.7 TB. 3.1 TB is Spare and 5.0 TB is Protected. 649.5 GB unused.
I was think what will happen, if unused space will fully utilized? do EMC ScaleIO able to rebalance and Rebuild or i need to increase the capacity of the unused spaced.
Thanks
jingxi02
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August 24th, 2020 21:00
The unused space is not important. The spare space is most important in fault tolerance role.
Base on my lab test and understanding, here is how the VxFlex fault tolerance work.
1. If the spare space is greater than one disk, your system can remain fault tolerate after one drive failure.
2. If the spare space is greater than total storage size in one node, your system can remain fault tolerate after one node failure.
3. If the spare space is greater than total storage of one fault domain, your system can remain tolerate after all nodes fail within one fault domain.
Tolerate means after a disk/node/fault domain failure, the system can fully rebuild data and maintain minimum two copies of data across all remaining drives.
For example, if your spare space is just greater than one disk, when you have one drive failure, your system will rebuild the data on the spare space. After the rebuild process, your system is still fully fault tolerance even without replace the first failed drive. When you have the second fail drive, your system is still going to fully operational. However, your data is not going to be able to maintain two copies across the remaining drives which is not going to be fault tolerance anymore. If you have 3rd drive failure, your data is going to be not accessible.
So keep in mind the spare space is the space to rebuild data after the fault. How much spare space you have, how much live storage can be failed and remain fault tolerance after the failure.