Maual SQL Server 2008 Desig, Optimize ad Maitai (70-450) 1-800-418-6789 Domai 1: Desigig a SQL Server Istace ad a Database Solutio Desigig for CPU, Memory ad Storage Capacity Requiremets Whe desigig a SQL server istace cosideratio must be give to the resources that will be utilized i that istace. What we will discuss i this sectio will be how to allocate those resources, how to desig ad cofigure a server istace, ad how to desig the physical database. Ad i additio to the server ad database, you will lear how to desig a migratio, cosolidatio, ad upgrade strategy. CPU Requiremets SQL Server 2008 requires a processor with a miimum speed of 1 GHz, but like most of Microsoft s requiremets you really should use the recommeded 2 GHz processor. This depeds somewhat o the OS but more is always better i the case of CPU speed. Whe selectig a CPU, both 32 bit ad 64 bit CPUs are supported by SQL Server 2008. There are, however, some beefits to usig the 64 bit architecture over the x86 architecture. We ll list those, below: Up to 8 TB of memory is supported Better bus architecture which equals higher speed ad better throughput Larger o-chip cache (L2 cache) Better chip cache maagemet Aother processor optio is a multicore processor. A multicore processor cotais two or more complete processors o the same chip. Each processor rus as a idepedet CPU with its ow L2 cache. A mai advatage of usig multicore processors is hyperthreadig. This allows multiple threads to ru simultaeously o a sigle CPU ad each processor keeps the state for each thread. To idetify CPU performace problems use the SQL Server pla cache couters. These couters are available usig the performace moitor (we will discuss later i Domai 5 of this maual) - ad iclude the followig statistics: Cache hits ratio Number of batch requests Number of compilatios per secod Number of recompilatios per secod LearSmart Cloud Classroom: Video Traiig Mauals
Maual SQL Server 2008 Desig, Optimize ad Maitai (70-450) 1-800-418-6789 Memory Cosideratios 32bit architecture has some limitatios whe it comes to memory usage. For istace, you ca oly access 4GB of memory directly ad oly 2GB is available for SQL Server with aother 2GB for the OS. However you ca up this by usig the /3GB switch i boot.ii to allow 3GB of memory per process. This leaves 1GB available for the OS. You ca also use the AWE (Address Widows Extesio) feature to use high memory for data buffers. Usig AWE however provides o beefit for stored procedure cache, some CLR fuctios or lock arrays. 64bit architecture provides 8GB of directly accessible memory with a full 7GB available to SQL Server - o switches activated. There is still 1GB available for the OS. Note: Although SQL Server 2008 ca access huge amouts of memory, the amout of actual memory available to SQL Server may be limited by the OS. NUMA Whe there are may processors i a sigle machie with oe memory cotroller, performace ca be limited because all of the processors are competig for access to memory through a sigle hardware chael. If you could divide the processors ito groups that each have their ow memory cotrollers -- to the poit where each processor is able to access memory without competitio -- you have maximum performace i regards to memory access. That s exactly what NUMA (No-uiform Memory Access) ca do for you. As more ad more processors became the orm i server desig, the eed for a hardware solutio to the problem of overloaded memory cotrollers icreased. NUMA was implemeted to meet that eed. NUMA hardware divides multiple processors ito small groups of processors (NUMA odes) that each have their ow memory ad sometimes their ow I/O cotrollers. This has icreased performace by elimiatig the memory access bottleeck i the older systems. SQL Server is NUMA aware ad works just fie o systems with NUMA desiged ito the hardware, without ay chages. NUMA is a scalable solutio to the limitatios of SMP (Symmetric Multiprocessig) architecture. The mai advatage of NUMA is scalability. The task of memory access is broke dow ito groups of CPUs with shared memory rather tha available memory beig shared by all CPUs i the server. Bottleecks are elimiated by limitig the umber of CPUs o ay oe memory bus ad providig access via a high speed itercoectio o each ode. There is aother cosideratio whe usig NUMA -- That is the differece i local ad foreig memory. Local memory is the memory that is ruig o the same ode as the CPU curretly ruig the thread. Foreig memory is memory that is ot ruig o the curret thread. Sice NUMA uses both local ad foreig memory it will take loger to access some memory tha others. NUMA Ratio is the ratio of foreig memory access time to local memory access time. Ideally this ratio should be 1 this idicates that it takes the same time to access foreig memory as it does local memory. A ratio of 2 idicates that it takes twice the time to access foreig memory as it does the local memory ad so forth. Some Widows applicatios ad SQL Server 2003 ad earlier, are ot NUMA aware ad will sometimes perform poorly with NUMA hardware. The NUMA cofiguratio is recorded i the server log as multimode cofiguratio alog with CPU mask whe the server is started. SQL Server 2008 supports both hardware NUMA ad soft NUMA. LearSmart Cloud Classroom: Video Traiig Mauals
Maual SQL Server 2008 Desig, Optimize ad Maitai (70-450) 1-800-418-6789 Hardware NUMA Computers with hardware NUMA have more tha oe system bus. The hardware determies the umber of CPUs that are served by a sigle bus ad each group of CPUs has its ow memory as well as its ow bus. A hardware NUMA ode is a collectio of CPUs, memory bus, ad I/O chaels. If you already have the hardware ad you re ot sure how may NUMA odes you have, you ca fid out by executig the query: SELECT DISTINCT memory_ode_id FROM sys.dm_os_memory_clerks If this query returs ode 0 oly, either you do t have hardware NUMA or your NUMA is cofigured for iterleaved memory. Software NUMA With SQL Server you ca group CPUs ito odes with software as well. This groupig is kow as soft- NUMA. Soft-NUMA is used whe you have may CPUs but you have o hardware NUMA or if you have a eed to divide the hardware odes ito smaller groups (odes). You do this by creatig a registry etry that describes your Soft NUMA setup. Soft NUMA does ot affect memory odes, oly CPU odes. I other words, with soft NUMA you ca oly group processors, but you have o cotrol over how the buses or memory are grouped, that s a fuctio of hardware oly. SQL Server has oly oe Lazy Writer ad oe I/O hadler. The I/O hadler hadles all of the I/O completes ad the Lazy Writer keeps the disk updated -- durig slow times i the system -- with chages made to memory. The problem: If you have a system with may CPUs ad may users the thread that hadles the Lazy Writer ad I/O could become a bottleeck. The solutio: Cofigurig may soft NUMA odes provides oe I/O thread ad oe Lazy Writer thread per ode. You ca divide hardware odes ito eve smaller groups (soft Nodes), but you must be careful ot to cross hardware ode boudaries whe you cofigure SQL Server for soft NUMA ad hardware NUMA is preset i the system. Let s say you have two hardware NUMA odes i your system, the first ode cotais CPUs 0-3 ad the secod ode cotais CPUs 4-7. You could create a soft NUMA ode to group processors 0 ad 1 together because they are both i the same hardware NUMA ode. Ad you could create aother ode to group processors 2 ad 3 together. But you ca t create a ode that would group processors 0 ad 4 together -- because you ca t cross hardware boudaries i a soft NUMA ode. LearSmart Cloud Classroom: Video Traiig Mauals
Maual SQL Server 2008 Desig, Optimize ad Maitai (70-450) 1-800-418-6789 How to Cofigure SQL Server for Soft NUMA As we metioed earlier, you cofigure soft NUMA odes by a registry etry -- here s how: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Microsoft SQL Server\100\NodeCofiguratio Type Value Name Value \Node 0 DWORD 0x03 \Node 1 DWORD 0x0c \Node 2 DWORD 0x30 \Node 3 DWORD 0xc0 Figure 1: NUMA Cofiguratio ple With the right most bit of the value represetative of CPU 0, the mask value selects which CPUs will be associated with which ode. I this case processors 0 ad 1 will be associated with ode 0, processors 2 ad 3 will be associated with ode 1, ad so forth. Storage Cosideratios Types of Storage SQL Server works best with disk drives that have high rotatio speeds ad low seek times. A more expesive optio is to use SANs (Storage Area Network) -- especially for high-ed, high cofiguratio systems. Always err o the side of more disk space. You must cosider I/O throughput as well. Eve with plety of disk space you could still have throughput issues. For example, if you use a two terabyte sigle drive ad you have multiple users, the time to access the sigle drive could slow the etire system. You should cosider the type ad amout of storage used as well. Here are some hardware cosideratios for disk storage: SQL Server works best with disk drives that have high rotatio speeds ad low seek times. You may eve cosider usig the more expesive SANs (Storage Area Network) -- especially for high-ed, high cofiguratio systems. You wat to always err o the side of more disk space - more is always better whe it comes to storage capacity. Ad you must cosider I/O throughput as well. Maagig Disk Storage Rotatio speed ad seek times are importat, but so is availability. Performace of a drive is equal to the speed of the reads ad writes. But the performace i a system is equal to the speed of the reads ad writes of the idividual drives ad the availability. I other words, you may have high performace drives, but limited availability will create bottleecks ad slow dow the etire system. Fault tolerace is the ability of the system to cotiue fuctioig through a system failure without a loss of data. LearSmart Cloud Classroom: Video Traiig Mauals
Maual SQL Server 2008 Desig, Optimize ad Maitai (70-450) 1-800-418-6789 You should cosider NTFS (New Techology File System) formatted drives with a 64KB allocatio table. Why a 64KB allocatio table? 64KB is the size of oe extet. Oe extet is equal to eight pages (oe page equals 8K of data) side by side. Some large I/Os ca read a etire extet at oe time so the miimum allocatio uit should be the same size as oe extet. Aother way to icrease performace is to spread data across may differet drives. This allows parallel scas of a table ad therefore icreases throughput. RAID ad SQL Server RAID (Redudat Array of Idepedet Disks) combies two or more hard disks i a sigle logical uit. The data is divided amog several disks i a array of disks that are see by the system as oe uit, therefore the risk of data loss due to a disk failure is reduced. Havig all data i a server stored o sigle disks that are treated idepedetly by the system is aki to havig all of your fiacial ivestmets i oe compay. If the compay fails, you risk losig all of your ivestmet. Spreadig data amog several disks with mirrorig or parity error correctio is a way to protect the itegrity of the data ad spreads the risk aroud so that oe failure caot cost you all your data ivestmet. This is the basis of RAID - although some cofiguratios have either redudacy or parity but do icrease performace. A mirrorig scheme, as the ame implies, writes the same data to two or more disks at oce makig a exact copy of all of the data writte to the origial. Parity provides a way to correct errors i the data o the fly. Note: Hardware RAID is better ad faster tha OS RAID. There are several RAID levels available that allow differig combiatios of performace, redudacy, ad error checkig. Levels 0, 1, ad 5 are the oes typically implemeted by the SQL Server so for test preparatio we will focus o these three cofiguratios. RAID 0 - Stripig I RAID level 0 disk stripig is used to separate the data ito blocks ad store data i a fixed order across the disk array. Miimum of two disks Data is writte to oe disk, the the other No fault tolerace Better read ad write performace Max disks ca be quite large Disk stripig is used at this level to improve the performace of read ad write operatios. With disk stripig several disks are arraged i a array so that idepedet read ad write operatios ca be performed at the same time to more tha oe disk, thus improvig performace. Data is divided ito blocks ad i a fixed order across the disk array. Data ca be writte ad read faster tha o a sigle disk. With o mirrorig or parity, a failure of a sigle disk ca cause loss of data. RAID Level 0 is similar to level 5 except there is o fault tolerace at level 0. Advatage: Better read ad write performace. Disadvatage: No fault tolerace. LearSmart Cloud Classroom: Video Traiig Mauals