Backup; Management; Iscsi Planning Considerations - IBM TotalStorage DS300 Best Practices Manual

2.4.4 Backup

Backup of data on the IP Storage is the same as for any direct attach storage;
that is, via any method that supports SCSI-attached volumes. A backup
application running on an external server, including the one hosting the iSCSI
initiator code, will control the backup of data that is physically stored on the iSCSI
appliance.
An NAS appliance, because it "hides" disk volumes from its clients, and often
includes specialized backup facilities, may be easier to install and manage.

2.4.5 Management

iSCSI is managed like any direct-attach SCSI device. iSCSI-connected disk
volumes are visible to attached processors. Compared to Fibre Channel SANs,
iSCSI benefits from using IP networks for which there are established network
management tools and people skills. Such tools enable network administrators to
coordinate provision of bandwidth among users and applications, traffic
management, and overall network operations. Training in new networking skills is
minimized.

2.5 iSCSI planning considerations

Since the iSCSI appliance attaches to the existing Ethernet network,
implementation is very similar to an NAS device. In this way, NAS and iSCSI are
very similar. However, when you make the comparisons between iSCSI, Fibre
Channel and NAS, it really comes down to Block I/O versus File I/O. Both iSCSI
and Fibre Channel use Block I/O to transport data, whereas NAS uses File I/O.
The determining factor might ultimately be what kind of application is to be used.
Will the application work better in a Block I/O environment, or File I/O
environment? Is the application database or file sharing oriented? How much
does performance play in this application?
All File I/Os result at a lower layer in Block I/Os. This means that iSCSI can also
support File I/O applications. However, if "visibility" and "sharing" of files are
needed, File I/O applications are better supported by NAS than by iSCSI devices.
Actual device sharing can only happen at the Block I/O level. This requires a
"share-aware" file system. Windows NTFS does not support this.
Chapter 2. iSCSI overview
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