Storage Changes in VMware vSphere 4.1

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Storage Changes in VMware vSphere 4.1A quick review of changes and new features

Scott Lowe, VCDX 39vSpecialist, EMC CorporationAuthor, Mastering VMware vSphere 4Blogger, http://blog.scottlowe.org

http://blog.scottlowe.org/


Storage Feature Summary• 8 Gbps FC HBA and expanded support for

FCoE CNAs

• New storage performance statistics

• Storage I/O Control

• vStorage APIs for Array Integration

• iSCSI enhancements


New Storage Performance Statistics• More comprehensive performance statistics

available both in vCenter and esxtop/resxtop– Historical/real-time via GUI in vCEnter– Real-time via esxtop/resxtop for

drill-down/scripting

• Latency and throughput statistics available for:

– Datastore per host– Storage adapter and path per host– Datastore per VM– VMDK per VM

• Greater feature parity across all storage protocols


Storage I/O Control


The I/O Sharing Problem

What You See Now What You Should See

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datastore

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Solution: Storage I/O Control (SIOC)

32GHz 16GB

Datastore A

CPU shares: High

Memory shares: Highonline store

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CPU shares: Low

Memory shares: Low

CPU shares: High

Memory shares: High

I/O shares: High I/O shares: LowI/O shares: High


Setting I/O Controls


Enabling Storage I/O Control

Storage I/O Control Enabled


Viewing Configuration Settings


Allocate I/O Resources• Shares translate into ESX I/O queue slots

– VMs with more shares are allowed to send more I/O’s at a time

– Slot assignment is dynamic, based on VM shares and current load

– Total # of slots available is dynamic, based on level of congestion

I/O’s in flight

STORAGE ARRAY

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Congestion Triggers SIOC• Congestion signal: ESX-array response time

> threshold– Default threshold: 30ms– Should set different defaults for SSD and SATA

• Changing default threshold (not usually recommended)

– Low latency goal: set lower if latency is critical for some VMs

– High throughput goal: set close to IOPS maximization point


vStorage APIs for Array Integration


Storage Integration Points

FC/FCoE & iSCSIArray APIs/Mgmt

vCenter

VAAI SCSI cmds

ESX Storage Stack

Datamover

Vendor-specific Plug-Ine.g. EMC Virtual Storage

Integrator

View VMware-to-Storage relationshipsProvision datastores more easily

Leverage array features (compress/dedupe, file/filesystem/LUN

snapshots

VI Client VM

Storage Array

VMFS NFS

NFSclient

Network Stack

VMware LVM

HBA Drivers

VSS via VMware Tools Snap request

SvMotion requestVM provisioning cmdTurn thin prov on/off

Vendor-specific VAAI SCSI command support

vStorage API for Multi-

pathing

NMP

Future NFS offloads

NFS

NIC Drivers

vStorage API for Data Protection

(VDDK)

Vendor Specific

vStorage API for SRM

SRM

VM-Aware Unisphere

Co-op

Co-

op


Current VAAI Primitives• Hardware-Accelerated Locking = 10-100x better metadata

scaling– Replace LUN locking with extent-based locks for better

granularity– Reduce number of “lock” operations required by using one

efficient SCSI command to perform pre-lock, lock, and post-lock operations

– Increases locking efficiency by an order of magnitude

• Hardware-Accelerated Zero = 2-10x lower number of IO operations

– Eliminate redundant and repetitive host-based write commands with optimized internal array commands

• Hardware-Accelerated Copy = 2-10x better data movement– Leverage native array Copy capability to move blocks


Hardware-Accelerated Locking• Without API

– Reserves the complete LUN so that it could obtain a lock

– Required several SCSI commands– LUN level locks affect adjacent hosts

• With API– Locks occur at a block level

One efficient SCSI command - SCSI Compare and Swap (CAS)

– Block level locks have no effect on adjacent hosts.

• Use Cases– Bigger clusters with more VMs– View, Lab Manager, Project Redwood– More & Faster VM Snapshotting


Parameter for Hardware-Accelerated Locking

Q: Can this be changed without a reboot?

A: Yes!


Hardware-Accelerated Zero• Without API

– SCSI Write - Many identical small blocks of zeroes moved from host to array for MANY VMware IO operations

– Extra zeros can be removed by EMC arrays after the fact by “zero reclaim”

– New Guest IO to VMDK is “pre-zeroed”

• With API– SCSI Write Same - One giant block of

zeroes moved from host to array and repeatedly written

– Thin provisioned array skips zero completely (pre “zero reclaim”)

• Use Cases– Reduced IO when writing to new blocks in

the VMDK for any VM– Time to create VMs (particularly FT-enabled

VMs

VMDK

SCSI WRITE (0000…..)SCSI WRITE (data)SCSI WRITE (0000….)SCSI WRITE (data)Repeat MANY times…

SCSI WRITE SAME (0 * times)SCSI WRITE (data)


Parameter for Hardware-Accelerated Zero

Q: Can this be

changed without a reboot?

A: Yes!


Hardware-Accelerated Copy• Without API

– SCSI Read (Data moved from array to host)– SCSI Write (Data moved from host to array)– Repeat– Huge periods of large VMFS level IO, done via

millions of small block operations

• With API– SCSI Extended Copy (Data moved within array)– Repeat– Order of magnitude reduction in IO operations– Order of magnitude reduction in array IOps

• Use Cases– Storage VMotion– VM Creation from Template

SCSI READSCSI READSCSI READ..MANY times…

SCSI EXTENDED COPY

SCSI WRITESCSI WRITESCSI WRITE..MANY times…

“let’s Storage VMotion”“let’s Storage VMotion”

“Give me a VM clone/deploy from template”


Parameter for Hardware-Accelerated Copy

Q: Can this be changed without a reboot?

A: Yes!


iSCSI Enhancements


iSCSI Enhancements in vSphere 4.1• Boot from software iSCSI (iBFT)

• iSCSI offloading

• iSCSI session management

• Additions have also been made to the CLI


Steps in Booting from Software iSCSI• Ensure that the NIC you wish to use supports iSCSI

Boot.

• Ensure that the NIC has a supported version of firmware.

• Ensure that iSCSI Boot option is selected in the host BIOS for the NIC.

• Configure the iSCSI Boot parameters in the NIC BIOS.

• Configure the iSCSI target to allow initiator (NIC) access.

• Configure a LUN on the iSCSI target and present to the initiator.


Q&A


THANK YOU

Storage Changes in VMware vSphere 4.1

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