SQL Server Then and Now: Changing the State of Long-held Beliefs. Maxwell Myrick Managing Partner SQLHA LLC

Transcription

1 SQL Server Then and Now: Changing the State of Long-held Beliefs Maxwell Myrick Managing Partner SQLHA LLC

2 Thank You SQLSAT Sponsors!

3 Maxwell Myrick Max is a 16 year Microsoft veteran which included 5 years on SQL Server development where he ran the SQL Customer Lab and then the Sustained Engineering team. He was an initial member of Microsoft's Mission Critical team where he worked directly with some of the largest SQL Server applications worldwide for 8 years. Max was also regular speaker for Microsoft at TechEd and TechReady as well as the creator of several new service offerings including the Monthly Hotfix Report. Four years ago, he joined SQLHA where he continues to work on mission critical system design, implementation, and support.

4 Agenda Part 1 Old Advice We ve All Heard Updated! Separate your Data and Log Files Disk Queue Length <= 2 Use RAID 1+0 for Log, RAID 5 for Data Myths of Tiered Storage Network Latency to Storage Off-Box Storage is Necessary for Space or Performance Part 2 A Glimpse of the Future

5 Disk Technology - HDD Platters, surfaces, and heads oh my! But really worked just like a record player Except the needle could jump around

6 Disk Technology - HDD

7 Disk Technology - HDD Platters, surfaces, and heads oh my! But really worked just like a record player Except the needle could jump around Sequential IO was fastest by far No Seek time Outer tracks were faster (Rotational Speed) Less data on disk was faster Less Seek Time Reads could be 16x speed of Writes

8 Disk Technology - SSD No moving parts! Really it s just like main memory Except slower clock cycle

9 Disk Technology - SSD

10 Disk Technology - SSD No moving parts! Really it s just like main memory Except slower clock cycle Fastest IO evenly uses all Memory Chips Fastest IO evenly uses all Controller Chips Key is to have enough Data / Files / Threads Reads and Writes much closer in speed Some SSDs are optimized for Read / some for Write

11 Separate Data and Log Files Yes on HDDs Data writes all over Log writes sequentially don t randomize with seeks No on SSDs (including all Flash storage types) Make sure you have enough data, files, and threads to use all chips and all controller channels Use Diskspd Utility to determine Use different vdisk labels for service monitoring

12 Disk Queue Length <= 2 Yes on HDDs Seek time is still a real thing Latency is in milliseconds (ms) which is a lot now Throughput is low, it cannot catch up quickly No on SSDs Disk Queue Length can be MUCH HIGHER! So fast; so little latency; so quick to catch up Use Diskspd Utility to determine Will have different thresholds for different SQL Server workloads

13 Use RAID 1+0 Log, RAID 5 Data Yes on HDDs RAID 5 slows writes (calculate parity) But RAID 5 reads up to 15x faster No on SSDs You still need RAID arguably more than ever! Parity cost trivial except on loss of disk You want to spread the load evenly - use RAID 6

14 Myths of Tiered Storage What is Tiered Storage you ask? Usually SSD, 15k rpm HDD, 7.2k rpm HDD Self-Optimizes moves busy data to faster storage Myth 1 Middle tier makes sense Reality Put that money toward more SSD or RAM The difference is so great faster HDDs don t matter Myth 2 Need lots of disks for speed Reality True for HDD, but only in the extreme for SSDs If you have all data on flash storage, probably fast enough If not, add RAM not more HDDs Myth 3 Tiered Storage Works Great Reality Most of them move data once per day They react slowly, so changing workloads are a bad fit

15 Network Latency to Storage Windows Server network latency (TCPIP) has vastly improved 5 ms latency on round trip used to be norm Now can do about 1.2 ms (or less) Now you can use remote storage with little latency Storage abstraction like SOFS often add 0 ms latency RDMA is absolutely amazing! But VMware support is lagging Windows support

16 Off-box Storage Necessary We used to need big SAN / NAS systems Needed a ton of disks for speed Sparsely filled them for speed (just outer tracks) Needed lots of controller channels Disks were large and power hungry Laptop drives can be used in racked servers Storage capacity numbers have exploded Local disks (DAS) can now both hold huge data sizes and provide high IOPS (SSD) Hyper-Converged Infrastructure is coming

17 DiskSpd Overview Wonderful new IO test harness from Microsoft Replaces SQLIO stress tool Injects IO to mimic SQL Server Can control some cache usage DispSpd is here: Now has a GUI called DiskSpeed:

18 DiskSpd Usage Workload IO Pattern IO Type Data Size / IO Data Activity Random Read 8k, 64k Data Activity Random Write 8k, 64k Data Activity Random Mixed (4:1) 8k, 64k Logs & Backups Sequential Read 8k, 64k Logs & Backups Sequential Write 8k, 64k Example Command Line DiskSpd.exe -c1000g d300 -r -w0 -t8 -o8 -b8k -h -L F:\testfile.dat > Results.txt

19 Looking Ahead #1 Let s take a glimpse into the FUTURE 1. Memory and Disk are blurring Memory was FAST but NON-PERSISTENT Disk was SLOW but PERSISTENT These are simply NOT TRUE anymore SSD/FLASH are both FAST and PERSISTENT Your smartphone has 1 type of storage which is both memory and disk And it s tiny, and cheap, and fast, and stores a lot

20 Looking Ahead #2 Let s take a glimpse into the FUTURE 2. We have an Architectural problem Memory and Disk are handled different on Motherboards

21 Disk Technology - SSD

22 Looking Ahead #2 Let s take a glimpse into the FUTURE 2. We have an Architectural problem Memory and Disk are handled different on Motherboards This will be hard to change It s holding us back

23 Looking Ahead #3 Let s take a glimpse into the FUTURE 3. Hyper-Converged Infrastructure Cloudy technologies like virtualization Software Defined - Everything Where resources are will matter less Any application will be able to get resources it needs Administration role changes, but remains

24 Questions?

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