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Scalability Limits

This topic provides the supported and tested Microsoft iSCSI Software Target 3.3 limits. The following tables display the tested limits and the enforced limits where applicable.

In addition, the following limits apply:

  • You should not use network adapter teaming with Microsoft iSCSI Software Target 3.3 for iSCSI communication.

  • If you plan to use multiple network adapters for iSCSI communication, you should separate them into their own subnets, set up virtual IP addresses, and then implement MPIO.

Microsoft iSCSI Software Target 3.3 support boundaries

Base configuration

Item Limit Enforced Comment

iSCSI target instances per appliance

256

Not enforced

 

Initiators that can connect to the same iSCSI target instance

16

Enforced

When used with MPIO, you can connect no more than 4 sessions per initiator.

iSCSI initiators per appliance

256

Not enforced

 

Virtual disks per appliance

256

Not enforced

 

Virtual disks per iSCSI target instance

128

Enforced

 

Simultaneous sessions

64

Enforced

 

Snapshots per virtual disk

512

Enforced

There is a limit of 512 snapshots per independent iSCSI application volume and 64 snapshots for file share volumes. If the iSCSI virtual disks and file shares are on a common volume, the iSCSI snapshot limit is 448 (512 – 64).

Locally mounted virtual disks or snapshots per appliance

32 (on stand-alone) 4 (on a cluster)

Enforced

 

Fault tolerance

Item Limit Enforced Comment

Failover cluster nodes

5

Not enforced

 

Error recovery level (ERL)

0

Enforced

 

Multiple connections per session (MC/S)

Not supported

Enforced

 

Simultaneous connections

64

Not enforced

 

Multipath Input/Output (MPIO)

Supported

N/A 

 

MPIO paths

4

Not enforced

 

Virtual disks over MPIO per initiator on a stand-alone server

64

Not enforced

There is an initial delay after creating the disks before they appear to the Virtual Disk Service and the Disk Management snap-in because PnP first detects the devices and then MPIO detects the paths for each disk. This happens only one time per disk per appliance.

Virtual disks over MPIO per initiator on a clustered application server

32

Not enforced

Converting stand-alone iSCSI Software Target to failover cluster or vice versa

Supported

N/A 

No VHD or target will be preserved.

Network

Item Limit Enforced Comment

Maximum number of active network ports

6

Not enforced

Applies to network ports that are dedicated to iSCSI traffic, rather than the total number of network ports in the appliance.

Network port speed

10 gigabits per second (Gbps)

Not enforced

IPv4

Supported

 

 

IPv6

Supported

 

 

TCP offload

Supported

 

 

iSCSI offload

Not supported

 

 

Jumbo frames

Supported

 

 

IPsec

Supported

 

 

iSCSI virtual disks

Item Limit Enforced Comment

From an iSCSI initiator, which converts the iSCSI target disk from a fixed disk to a dynamic disk

Not supported

Not enforced 

 

VHD minimum size format

8 MB

Enforced 

 

Parent VHD size

2088890 MB

Enforced

Fixed VHD size

16776703 MB

Enforced

Differencing VHD size

2088960 MB

Enforced

VHD fixed format

Supported

N/A

VHD differencing format

Supported

N/A

VHD dynamic format

Not supported

N/A

FAT/FAT32 (hosting volume of the VHD)

Not supported

Not enforced

NTFS

Supported

N/A

NTFS cluster size

4 KB

N/A

Non-Microsoft CFS

Not supported

Enforced

Number of differencing VHDs per parent VHD

256

Not enforced

Number of parent VHDs per differencing VHDs

1

Enforced

 

Number of boot operating systems that can be installed on one VHD

1

Not enforced

Thin provisioning

Not supported

N/A

LUN shrink

Not supported

N/A

LUN cloning

Not supported

N/A

 

Windows operating systems on which the VDS and VSS hardware providers are supported

Operating system Limit Enforced

Windows Server 2003 R2 x64

Supported

Enforced

Windows Server 2003 R2 x86

Supported

Enforced

Windows Server 2008 SP2 x64

Supported

Enforced

Windows Server 2008 SP2 x86

Supported

Enforced

Windows Server 2008 R2 x64

Supported

Enforced

Windows Storage Server 2008 x64

Supported

Enforced

Windows Storage Server 2008 x86

Not supported

Enforced

Windows Storage Server 2008 R2 x64

Supported

Enforced

All client operating systems (Windows XP, Windows Vista, Windows 7)

Not supported

Enforced

iSCSI Software Target provider interoperability

iSCSI target version iSCSI provider version Supported

3.1

3.1

Supported

3.2

3.1

Not supported

3.2

3.1 (in-place upgrade)

Not supported

3.1

3.2

Supported

3.2

3.2

Supported

3.2

3.3

Supported

3.3

3.3

Supported

Note

In-place upgrades from Microsoft iSCSI Software Target 3.1 to Microsoft iSCSI Software Target 3.3 are not supported. To upgrade to Microsoft iSCSI Software Target 3.3, you must first uninstall Microsoft iSCSI Software Target 3.1.

iSCSI Software Target virtual disk compatibility

Created in version Mounted in version Supported

3.0

3.1

Not supported

3.0

3.2

Supported

3.1

3.2

Supported

3.1

3.3

Supported

3.2

3.3

Supported

Microsoft iSCSI Software Target snap-in interoperability

Snap-in installed on Managing iSCSI target on Supported

Windows Server 2008 R2

Windows Server 2008 R2

Supported

Windows Server 2008 R2, stand-alone server

Windows Server 2008 R2, failover cluster node

Supported

Windows Server 2008 R2, failover cluster node

Windows Server 2008 R2, stand-alone server

Supported

Snap-in installed on Managing iSCSI target on Supported

Windows Storage Server 2008 R2

Windows Storage Server 2008 R2

Supported

Windows Storage Server 2008 R2, stand-alone server

Windows Storage Server 2008 R2, failover cluster node

Supported

Windows Storage Server 2008 R2, failover cluster node

Windows Storage Server 2008 R2, stand-alone server

Supported

Miscellaneous

Item Supported

Install Microsoft iSCSI Software Target 3.3 snap-in on Windows XP, Windows Vista, or Windows 7

Not supported

Install Microsoft iSCSI Software Target 3.3 snap-in on x86 version of Windows Storage Server 2008

Not supported

Use Microsoft iSCSI Software Target 3.3 snap-in to manage Microsoft iSCSI Software Target 3.2 target

Supported

Use Microsoft iSCSI Software Target 3.2 snap-in to manage Microsoft iSCSI Software Target 3.3 target

Not supported