Demystifying Hardware - SQL Server 2012 Internals and Troubleshooting - page 47

Ensure that you have dual power supplies for the database server, each plugged into separate circuits
in your server room or data center. You should also be plugged into an uninterruptable power sup-
ply (UPS) on each circuit, and ideally have a backup power source, such as a diesel generator for
your data center. The idea here is to protect against an internal power supply failure, a cord being
kicked out of an electrical socket, a circuit breaker tripping, or loss of electrical power from the
utility grid. Adding a second power supply is relatively inexpensive insurance, typically less than
$300. Despite this, we have seen many battles with economizing bosses about this item over the
years. Power supplies do fail, cords are accidentally unplugged, and circuit breakers do get tripped.
Therefore, stick to your guns about dual power supplies for a database server. You should have
multiple network ports in the server, with Ethernet connections into at least two different network
switches. These network switches (which should also have dual power supplies) should be plugged
into different electrical circuits in your data center. Most new rack-mounted servers have at least
four gigabit Ethernet ports embedded on the motherboard. All of this is designed to prevent an out-
age caused by the loss of a single network port or a single network switch.
You should have multiple RAID controller cards (if you are using direct-attached or internal stor-
age); multiple host bus adapters (HBAs) (if you are using a Fibre Channel SAN); or multiple PCIe
Gigabit, or better Ethernet cards with an iSCSI SAN. This will give you better redundancy and bet-
ter throughput, depending on your coni guration. Again, the idea here is to try to avoid an outage
caused by the loss of a single component.
Wherever your SQL Server data i les, log i les, tempdb i les, and SQL Server backup i les are located,
they should be protected by an appropriate RAID level, depending on your budget and performance
needs. You want to prevent your databases from going down due to the loss of a single drive. Keep in
mind that RAID is not a substitute for an appropriate SQL Server backup and restore strategy! Never
let anyone, whether it is a SAN vendor, a server administrator from your operations team, or your
boss, talk you into not doing SQL Server backups as appropriate for your recovery point objective
(RPO) and recovery time objective (RTO) requirements. This cannot be emphasized enough! There is
absolutely no substitute for having SQL Server backup i les, although you will undoubtedly be pres-
sured throughout your career, by different people, into not running SQL Server database backups.
Stand your ground. The old saying is true: “If you don't have backups, you don't have a database.”
To reduce the boot and SQL Server startup time on your database servers, note the following BIOS
coni guration setting. For a standalone database server, reducing your total reboot time has a direct
effect on your high-availability numbers. Therefore, go into the BIOS setup for the server and dis-
able the memory testing that normally occurs during the POST sequence, which shaves a signii cant
amount of time off of it (often many minutes, depending on how much RAM is installed), so the
server will boot faster. This carries little risk, as this testing only occurs during the POST sequence;
it has nothing to do with detecting a memory problem while the server is running later, which is the
job of your hardware or system-monitoring software.
While you are in the BIOS setup, also access the Power Management section and either disable
the power management settings or set them to OS control. By default, Windows Server 2008 and
Windows Server 2008 R2 use the Windows Balanced Power Plan. This saves electrical power usage
by reducing the multiplier setting for the processors, which reduces their clock speed when the sys-
tem is not under a heavy load. This sounds like a good idea, but it can actually have a very signii -
cant negative effect on performance, as some processors do not react quickly enough to an increase