But doesn't using thin provisioning hurt performance due to fragmentation as the disk grows?
OK, lets dispell 3 myths.
1) ALL file systems get fragmented, period end of subject (EXT3, NTFS, FAT32, Unix, ZFS, etc..).
2) Thin Provision has NOTHING at all to do with performance, ZERO. It has to do with space consumption. You allocated a VM to occupy 30GB of space. You either grow this VM until it REACHES the size you wanted over time or you PRE-ALLOCATE at the time you set up the file, that's the ONLY difference.
3) There MAY be a slight overhead to increase the file (in 2 GB increments) and depending on the SAN storage you use and the way you provision it (NFS, Fiber, iSCSI) as well as type of disks (SAS vs SATA) it may or may not have an impact.
But Thin provision in and of itself does NOT affect performance, its either allocate the space NOW or LATER your choice. The only downside to thin provision since you don't see how much space you WILL use and you could over commit your space.
