Storage for the DBA

Storage for the DBADenny Cherry

Manager of Information [email protected]

MVP, MCSA, MCDBA, MCTS, MCITP

AgendaStorage TerminologyArray Cache SetupRAID TypesTiered StorageDisk AlignmentSpindle TypesPhysical Array Diagram

Storage TerminologyLUN = Logical Unit NumberHost = The Server or Servers a LUN is

presented toSAN = Storage Area NetworkFabric = Fibre network which makes up the

SANArray = Box with the Spindles in it

Storage TerminologyDisk = How the OS sees a LUN when

presentedSpindle = Physical disks in the Storage ArrayIOps = Physical Operation To DiskSequential IO = Reads or writes which are

sequential on the spindleRandom IO = Reads or writes which are

located at random positions on the spindle

Cache SetupOLTP databases make poor use of SAN read

cacheOLAP databases make good use of SAN read

cacheTry reducing read cache and increasing write

cacheOLTP databases with high buffer cache hit ratios

may be able to have the read cache disabledThere is no one correct setup. Every system is

different.

RAID TypesRAID 1

Full Mirror of dataNo performance Benefit

RAID 0+1Drives Striped, then Stripes MirroredHigh Cost, but High Performance

RAID 10 (aka 1+0)Drives Mirrored, then Mirrors StripedHigh Cost, but High Performance

RAID TypesRAID 5

Stripe with single parity driveLow cost, good performanceWrite penalty

RAID 6Stripe with two parity drivesSlightly higher cost per gig than RAID 5, good

performanceSame write penalty as RAID 5

Tiered StorageTier 1

15k RPM Fibre Channel low capacity drivesHigh cost, high speed storageDatabases, Exchange, Virtual Machines

Tier 210k RPM Fibre Channel medium capacity

drivesMedium cost, medium speed storageFile Servers, Database Archives

Tiered StorageTier 3

7.2/5.4k RPM SATA/SAS high capacity drivesLow cost, low speed storageBackups, Archives

Tier 0Enterprise Flash Disks low capacity drivesVery high cost, very high speed storageDatabases

Disk Alignment• Can improve SQL disk performance up

to 100%• (64 1k blocks/64k IO)=100% of IO is

impacted• Must be done before data is put on the

disk• Windows 2000 - Diskpar• Windows 2003 - Diskpart• Windows 2008 - Automatic

Spindle TypesFibre Channel (FC)

Fastest Bus Speeds between 2-4 GigsSCSI

Older Technology, slower bus speedsSATA

Newer Technology, even slower bus speedsEnterprise Flash Disks (EFDs)

Newest Technology, same bus speeds as FC

Array Diagram

Denny [email protected]

http://itke.techtarget.com/sql-server

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