Virtualization and SAN Basics for DBAs

VMs, SAN, SQL:The Big Threes
Brent OzarQuest Software
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I’m Your Host: Brent Ozar
Microsoft Certified Master
SQL Server MVP
Quest Software
Past Lives: DBA, SAN, VMware admin
www.BrentOzar.com
Twitter: @BrentO

Today’s Big Threes
3 “Nevers” for VMs
3 “Always” for SAN
3 Metrics for Both
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Some Definitions

Our Host
2 Sockets4 Cores Each
64GB RAM
1 Terabyte SAN
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The Brochure Says…

CPU Scheduling

Not So Fast!

Never OverallocatevCPUs
Less is More
Every Tick Matters
Minimize CPU Work
Don’t Be Strict
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So What About Memory?
Host: 64GB
Guest: 16GB
Other Guests: 32GB
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So What About Memory?
Host: 64GB
Guest: 16GB
Other Guests: 80GB
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How Hypervisors Cope
Host page file
Dedupe memory(page sharing)
Keep guest OSmemory freed up
Learn more inmy bookmarks:http://delicious.com/brento/balloon
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Never Use Automatics
Set SQL Server’s min/max memory
Set VMware’s reservation size
Use locked pagescarefully
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Physical Storage Setup

In Virtualization…

Behind the Curtain

Think You’re Alone?

Never Assume VMs are Alone
Guests move
Guests get created
Competition: virus scans, scheduled tasks, backups
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Always Know Your Neighbors
Same disks
Same cache
Same controller
Same SAN
Ask:
Usage pattern?
Scheduled jobs?
Antivirus?
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Design Storage as a Whole
Backup schedules
Backup methods
Backup targets
Use differentials
Stagger job times
Reconfigure antivirus

Typical SAN Components
Drive enclosures
Controllers (& Cache)
Switch networks
Host Bus Adapters
HBA Drivers
Servers

Lots of Paths for Data

What Does Active/Active Mean?
One path per LUN
Sending vs receiving
Network design
Post-failover stickiness

Got High Speed?

So You Tested This Too, Right?
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Always Test First with SQLIO
Doesn’t use SQL Server
Doesn’t mimic SQL Server
Doesn’t return SQL metrics
Therefore: SAN guys love it!

The Easy Way

SQLIO Results
E:Program Files (x86)SQLIO>sqlio -kW -t2 -s120 -dM -o1 -frandom -b64 -BH -LS Testfile.dat
sqlio v1.5.SG
using system counter for latency timings, -1361967296 counts per second
2 threads writing for 120 secs to file M:Testfile.dat
using 64KB random IOs
enabling multiple I/Os per thread with 1 outstanding
buffering set to use hardware disk cache (but not file cache)
using current size: 24576 MB for file: M:Testfile.dat
initialization done
CUMULATIVE DATA:
throughput metrics:
IOs/sec: 1539.50
MBs/sec: 96.21
latency metrics:
Min_Latency(ms): 0
Avg_Latency(ms): 0
Max_Latency(ms): 572
histogram:
ms: 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24+
%: 66 32 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0

Good Numbers, Bad News
iSCSI
1GB = 125 MB/sec
10GB = 1250 MB/sec
Fibre Channel:
2GB = 250 MB/sec
4GB = 500 MB/sec

Which Causes An Outage?
New neighbors
RAID restripe
Drive failure
Cable change
Firmware change
Switch upgrade
Controller reboot
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Where Will You See Changes?
Windows event log
SQL Server logs
Profiler traces
Net Send popups
Your dreams at night

Always Be Checking
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My 3 Favorite Metrics
Physical Disk: Avg Sec/Read and Write
System: Processor Queue Length
SQL Server Memory: Page Life Expectancy

It’s Not All Bad News!
Easier scaling
Less firmware outages
No leased hardware cycles
Easier disaster recovery
Easier dinosaur handling

Wrapping It Up
Virtualization Nevers:
OverallocatevCPUs
Use automatics
Assume your VM is alone
SAN Always’s:
Know your neighbors
Test first with SQLIO
Be checking

http://www.BrentOzar.com/go/virtual

Our Book
Internals:
Memory
Locking
Storage
Troubleshooting:
Perfmon/Profiler
RML Utilities
SQLNexus

Our Authors
Christian BoltonMVP, MCM, MCAFormer Microsoft PFE
Justin LangfordFormer MS PFE
Brent OzarMCM, MVP
James Rowland-JonesMVP, EMC Consulting
Steven WortMicrosoft Developer

Paperbacks & PDF Versions:SQLServerTroubleshooting.com

Virtualization and SAN Basics for DBAs

by Quest Software on Apr 29, 2010

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Virtualization and SAN Basics for DBAs — Presentation Transcript