6.5.1
Table Of Contents
- vSphere Storage
- Contents
- About vSphere Storage
- Updated Information
- Introduction to Storage
- Getting Started with a Traditional Storage Model
- Overview of Using ESXi with a SAN
- Using ESXi with Fibre Channel SAN
- Configuring Fibre Channel Storage
- Configuring Fibre Channel over Ethernet
- Booting ESXi from Fibre Channel SAN
- Booting ESXi with Software FCoE
- Best Practices for Fibre Channel Storage
- Using ESXi with iSCSI SAN
- Configuring iSCSI Adapters and Storage
- ESXi iSCSI SAN Requirements
- ESXi iSCSI SAN Restrictions
- Setting LUN Allocations for iSCSI
- Network Configuration and Authentication
- Set Up Independent Hardware iSCSI Adapters
- About Dependent Hardware iSCSI Adapters
- About the Software iSCSI Adapter
- Modify General Properties for iSCSI Adapters
- Setting Up iSCSI Network
- Using Jumbo Frames with iSCSI
- Configuring Discovery Addresses for iSCSI Adapters
- Configuring CHAP Parameters for iSCSI Adapters
- Configuring Advanced Parameters for iSCSI
- iSCSI Session Management
- Booting from iSCSI SAN
- Best Practices for iSCSI Storage
- Managing Storage Devices
- Storage Device Characteristics
- Understanding Storage Device Naming
- Storage Rescan Operations
- Identifying Device Connectivity Problems
- Edit Configuration File Parameters
- Enable or Disable the Locator LED on Storage Devices
- Erase Storage Devices
- Working with Flash Devices
- About VMware vSphere Flash Read Cache
- Working with Datastores
- Types of Datastores
- Understanding VMFS Datastores
- Understanding Network File System Datastores
- Creating Datastores
- Managing Duplicate VMFS Datastores
- Increasing VMFS Datastore Capacity
- Administrative Operations for Datastores
- Set Up Dynamic Disk Mirroring
- Collecting Diagnostic Information for ESXi Hosts on a Storage Device
- Checking Metadata Consistency with VOMA
- Configuring VMFS Pointer Block Cache
- Understanding Multipathing and Failover
- Raw Device Mapping
- Software-Defined Storage and Storage Policy Based Management
- About Storage Policy Based Management
- Virtual Machine Storage Policies
- Working with Virtual Machine Storage Policies
- Populating the VM Storage Policies Interface
- Default Storage Policies
- Creating and Managing VM Storage Policies
- Storage Policies and Virtual Machines
- Assign Storage Policies to Virtual Machines
- Change Storage Policy Assignment for Virtual Machine Files and Disks
- Monitor Storage Compliance for Virtual Machines
- Check Compliance for a VM Storage Policy
- Find Compatible Storage Resource for Noncompliant Virtual Machine
- Reapply Virtual Machine Storage Policy
- Using Storage Providers
- Working with Virtual Volumes
- About Virtual Volumes
- Virtual Volumes Concepts
- Virtual Volumes and Storage Protocols
- Virtual Volumes Architecture
- Virtual Volumes and VMware Certificate Authority
- Snapshots and Virtual Volumes
- Before You Enable Virtual Volumes
- Configure Virtual Volumes
- Provision Virtual Machines on Virtual Volumes Datastores
- Virtual Volumes and Replication
- Best Practices for Working with vSphere Virtual Volumes
- Filtering Virtual Machine I/O
- Storage Hardware Acceleration
- Hardware Acceleration Benefits
- Hardware Acceleration Requirements
- Hardware Acceleration Support Status
- Hardware Acceleration for Block Storage Devices
- Hardware Acceleration on NAS Devices
- Hardware Acceleration Considerations
- Thin Provisioning and Space Reclamation
- Using vmkfstools
- vmkfstools Command Syntax
- The vmkfstools Command Options
- -v Suboption
- File System Options
- Virtual Disk Options
- Supported Disk Formats
- Creating a Virtual Disk
- Initializing a Virtual Disk
- Inflating a Thin Virtual Disk
- Converting a Zeroedthick Virtual Disk to an Eagerzeroedthick Disk
- Removing Zeroed Blocks
- Deleting a Virtual Disk
- Renaming a Virtual Disk
- Cloning or Converting a Virtual Disk or RDM
- Extending a Virtual Disk
- Upgrading Virtual Disks
- Creating a Virtual Compatibility Mode Raw Device Mapping
- Creating a Physical Compatibility Mode Raw Device Mapping
- Listing Attributes of an RDM
- Displaying Virtual Disk Geometry
- Checking and Repairing Virtual Disks
- Checking Disk Chain for Consistency
- Storage Device Options
Figure 13‑1. Single Ethernet Link Connection to Storage
When systems read data from storage, the storage responds with sending enough data to fill the link
between the storage systems and the Ethernet switch. It is unlikely that any single system or virtual
machine gets full use of the network speed. However, this situation can be expected when many systems
share one storage device.
When writing data to storage, multiple systems or virtual machines might attempt to fill their links. As a
result, the switch between the systems and the storage system might drop network packets. The data
drop might occur because the switch has more traffic to send to the storage system than a single link can
carry. The amount of data the switch can transmit is limited by the speed of the link between it and the
storage system.
Figure 13‑2. Dropped Packets
1 Gbit
1 Gbit
1 Gbit
dropped packets
Recovering from dropped network packets results in large performance degradation. In addition to time
spent determining that data was dropped, the retransmission uses network bandwidth that can otherwise
be used for current transactions.
iSCSI traffic is carried on the network by the Transmission Control Protocol (TCP). TCP is a reliable
transmission protocol that ensures that dropped packets are retried and eventually reach their
destination. TCP is designed to recover from dropped packets and retransmits them quickly and
seamlessly. However, when the switch discards packets with any regularity, network throughput suffers.
The network becomes congested with requests to resend data and with the resent packets. Less data is
transferred than in a network without congestion.
Most Ethernet switches can buffer, or store, data. This technique gives every device attempting to send
data an equal chance to get to the destination. The ability to buffer some transmissions, combined with
many systems limiting the number of outstanding commands, reduces transmissions to small bursts. The
bursts from several systems can be sent to a storage system in turn.
vSphere Storage
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