The Latest Gartner® Magic Quadrant™Hyperconverged Infrastructure Software
Moderators: anton (staff), art (staff), Max (staff), Anatoly (staff)
Code: Select all
1) Our initiator fills the target with 10 Z blocks:
Target ZZZZZZZZZZ
Disk Z-------------------
Map Z:10
Starwind just writes one Z to the disk, and records that there are 10 duplicates of Z. We have 19 blocks free on our physical disk.
2) The initiator starts writing some random data to the target
Target ZZZZZZZZZZ
Target ITISAPERIO
Disk -ITSAPERO-----------
Map Z:1 I:3 T:2 S:1 A:1 M:1
The new blocks I, T, S, A, P, R and D get written to the disk. Note that the count for Z has disappeared. This was achieved by decrementing the counter for Z each time a Z block was replaced by something else. When it reached zero, the Z block was deleted. We have 11 blocks free on our physical disk.
3) The initiator continues writing some random data to the target
Target DOFCIVILWA
Disk -I--A---ODFCVLW-----
Map I:2 D:1 F:1 C:1 V:1 L:1 W:1 A:1
11 blocks are free
4) The initiator continues channeling GL
Target RREBELSPAC
Disk ----A------C-LWREBSP
Map R:2 E:2 B:1 L:1 S:1 P:1 A:1 C:1
Still 11 blocks are free
If we didn't have this counting method coupled with deleting unused blocks, the physical disk would be looking like this:
1) Z-------------------
2) ZITSAPERO-----------
3) ZITSAPERODFCVLWA----
4) ZITSAPERODFCVLWABP--
only two free blocks; the next two unique blocks written would fill our physical disk.