iSCSITarget使用指南

to vSAN vSphere Replication can deliver a 5-minute recover point objective.

1.2 Application Clustering Solutions

Application Clustering Solutions

While it should be noted that vSphere High Availability, Fault Tolerance, and Replication can cover the vast majority of use

cases in an easy to manage, low cost manner, there are a number of use cases for application level clustering. It should be

noted that iSCSI will enable some new application clustering options, while others work today simply having VMDKs stored

on VMware vSAN.

Microsoft SQL

Microsoft Always ON Availability Groups

Operate in a true shared nothing fashion. They can be con?gured for either local synchronous replication, or remote

asynchronous replication. They are fully supported using native VMDK objects stored on vSAN storage.

Failover Clustering Instance (FCI)

FCI is NOT supported on VMware vSAN.

Microsoft File Services

Microsoft has a number of of availability solutions for ?le services. Built into their server operating system.

Distributed File System Replication DFS-R

The Distributed File System Replication (DFS-R) service replication engine that can keep folders synchronized using

compression and di?erential comparison. DFS-R works in a shared nothing environment and is fully supported using native

VMDK objects stored on VMware vSAN storage.

File Server Failover clustering

2008R2 2012R2 Failover Cluster

Traditional File Server clustering in windows server requires SCSI-3 locking, and shared storage. This is not supported on

VMware vSAN.

2012/2012R2 SoFS Cluster

Traditional File Server clustering in windows server requires SCSI-3 locking, and shared storage. While SoFS has

advantages over traditional failover clustering there are limitations on what is recommended or supported in using SoFS vs.

traditional failover clusters.

Windows 2016 Storage Replica (SR)

Storage Replicas are agnostic to storage hardware and has no speci?c storage hardware requirements. It is supported and

will run on top of VMware vSAN.

Exchange

Exchange as of Exchange 2010 no longer uses shared volumes for clustering. Database Availability Groups (DAG) use a

shared nothing design, and is fully supported using native VMDK objects stored on a vSAN datastore.

Oracle

Virtualized Oracle on vSAN is fully supported using native VMDK objects stored on a vSAN datastore. Note, you will need to

use the multi-writer ?ag and there are a number of considerations (no HotExtend, VADP, CBT support). See KB 2121181 for

more information.

Physical servers running Oracle RAC are supported with VMware vSAN using the iSCSI Target Service. Support is being

extended speci?cally for Oracle RAC 12c, 11gR2.

1.3 Third party solutions

Third party solutions

3rd party solutions also o?er a variety of replication solutions using both VMware vSphere Storage APIs – Data Protection

(Formerly known as VADP) as well as using vSphere APIs for I/O Filtering (VAIO).

VMware guidance: vSphere High availability o?ers an excellent RPO and RTO for most workloads, and vSphere replication.

When lower recovery times are needed, should be application level clustering often no longer requires clustered volumes.

2. Security Guidance

iSCSI, like any storage protocol, requires proper security considerations.

2.1 Private Network

Private Network

iSCSI storage tra?c is transmitted in an unencrypted format across the LAN. Therefore, it is considered best practice to use

iSCSI on trusted networks only and to isolate the tra?c on separate physical switches or to leverage a private VLAN. All

iSCSI-array vendors agree that it is good practice to isolate iSCSI tra?c for security reasons. This would mean isolating the

iSCSI tra?c on its own separate physical switches or leveraging a dedicated VLAN (IEEE 802.1Q).

2.2 Encryption and Authentication

Authentication

CHAP (Challenge Handshake Authentication Protocol) veri?es identity using a hashed transmission. The target initiates the

challenge. Both parties know the secret key. It periodically repeats the challenge to guard against replay attacks. CHAP is

supported by the vSAN iSCSI Target service. bidirectional CHAP is supported.

3. Availability and Performance Best Practices

Best practices for scaling availability and performance.

3.1 Availability Best Practices

Availability Best Practices

Multi-Path IO (MPIO) is supported with the vSAN iSCSI Target Service. Every target has an owner and initial connections will

be redirected using iSCSI redirects to the owning path. In the event of failure reconnection attempts will be redirected to the

new owning target. An initiator can connect to any host, but will always be redirected to the current active host.

3.2 Performance Best Practices

Performance Considerations

iSCSI Targets have a limited maximum queue depth and it is recommended to utilize more targets to increase performance. It

should be noted that a given target will only be active for a single host so

deploying more targets will lead to a more even usage of paths for performance balancing. You can see the I/O owning Host

from within the UI. It should be noted that iSCSI utilizes more compute overhead, and because of added pathing will add

additional latency and overhead compared to running Virtual Machine disks directly on the VSAN datastore. If performance is

a concern, iSCSI should only be used when native VSAN is not an options.

4. Interoperability and Support Considerations

Discussions on supported con?gurations.

4.1 Interoperability Considerations

vSAN policies and capabilities

As the iSCSI LUNs are stored as VMDK’s SPBM (Storage Policy Based Management) can be used to manage the

characteristics of the LUNs. Space e?ciency features including RAID-5 and Deduplication and Compression are fully

supported.

4.2 vSphere and VMware feature support

ESXi host support

Use of the Virutal SAN iSCSI Target for providing storage directly to vSphere is not currently supported. The intent of this

feature is to provide for extended use cases where application clustering requires it, as well as physical workloads outside of

the VSAN cluster.

vSphere and VSAN features not currently supported

The following features are not supported by iSCSI Target service volumes.

vSphere Replication

vSphere Data Protection API’s

Snapshots

SRM

For data protection, in guest tools, agents, or application level data replication tools will need to be leveraged. For failing over

to a second site, a stretched vSAN cluster would need to be used.

4.3 Supported Operating Systems

Supported Operating Systems

Windows 10, Windows 2016 , 2012 R2, 2012, 2008 R2, 2008

RHEL 7, RHEL 6, RHEL 5

SUSE Linux Enterprise Server 12, SLES 11 SP4/SP3/SP1

Hardware HBA's are not supported at this time.