I've just put in 4 x 4TB 00'ed drives and it's taking 14hours to "sync", well nothing should be syncing lets be clear, why is it taking so long to initlaise a RAID5 array?
I've just put in 4 x 4TB 00'ed drives and it's taking 14hours to "sync", well nothing should be syncing lets be clear, why is it taking so long to initlaise a RAID5 array?
RAID creates a virtual disk (block storage); the file system is built on top of that. So creating/syncing the RAID array takes the same amount of time when the file system is empty as it does when it is full.
Therefore, 16 TB of disk I/O is needed to sync the array (even with no data) - 12 TB to read the data blocks, and 4 TB to write the parity blocks. That takes a while. If it takes 14 hours, it will be processing ~300 MB/sec.
This could be faster if the system assumed the disks were zeroed. But it doesn't make any assumptions about what's on the drives.
