The thin LUN was mapped to the Windows server 2012, it was fast to format the LUN in the first time, but it was very slow to re-format it in second time. When turning on the performance monitoring tool, we can see the duration and bandwidth as below:
for the first time, it finished within 5 minutes; but for the second time, it took about 20 hours.
1. With the performance data from the storage, we can see the bandwidth is about 360MBps when formatting the 32TB LUN, the whole formatting progress last for about 20 hours. Due to the large amount of IOs, the “quick format” is just not like a real quick format for the storage.
2. We checked this problem with Microsoft, when formatting the thin LUN for the second time, there will be extra operation, such as "UNMAP" command, to start the space reclaimation.
To disable the function:
To enable the function: