Advanced Copy Services; Flashcopy - IBM V7000 Introduction And Implementation Manual

Table 2-9 shows differences between the use of FCoE and iSCSI for transfer environments.
Table 2-9 FCoE and iSCSI differences
FCoE
Local-area, lossless links, no routing allowed
Simple encapsulation of Fibre Channel
Low overhead – similar to Fibre Channel
Storage administrators know Fibre Channel well
Frame loss can quickly become catastrophic
FCoE allows for fewer network adapters to be required, as both protocols can share the same
adapter, reducing hardware cost and freeing up bus slots in hosts.
For in-depth details and recommendations for using these protocols, see Storage and
Network Convergence Using FCoE and iSCSI, SG24-7986 available at this website:
http://w3.itso.ibm.com/abstracts/sg247986.html?Open

2.7 Advanced copy services

IBM Flex System V7000 Storage Node supports the following copy services:

FlashCopy

Synchronous Remote Copy
Asynchronous Remote Copy
2.7.1 FlashCopy
FlashCopy makes a copy of a source volume on a target volume. After the copy operation has
started, the target volume has the contents of the source volume as they existed at a single
point in time. Although the copy operation takes time, the resulting data at the target appears
as though the copy was made instantaneously.
FlashCopy is sometimes described as an instance of a time-zero (T0) copy or a point in time
(PiT) copy technology.
FlashCopy can be performed on multiple source and target volumes. FlashCopy permits the
management operations to be coordinated so that a common single point in time is chosen
for copying target volumes from their respective source volumes.
IBM Flex System V7000 Storage Node also permits multiple target volumes to be
FlashCopied from the same source volume. This capability can be used to create images
from separate points in time for the source volume, and to create multiple images from a
source volume at a common point in time. Source and target volumes can be thin-provisioned
volumes.
Reverse FlashCopy enables target volumes to become restore points for the source volume
without breaking the FlashCopy relationship and without waiting for the original copy
operation to complete. IBM Flex System V7000 Storage Node supports multiple targets and
thus multiple rollback points.
iSCSI
Allows many hops, lossy connections and high
latency
Substantial complexity on top of TCP
Overhead varies - typically higher
TCP/iP well understood by most IT staff
Frame loss recovery built into protocol stack
Chapter 2. Introduction to IBM Flex System V7000 Storage Node
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