Servers CPTE 433 John Beckett. Server Hardware Extensible More CPU performance High-performance I/O...
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Transcript of Servers CPTE 433 John Beckett. Server Hardware Extensible More CPU performance High-performance I/O...
Servers
CPTE 433John Beckett
Server Hardware
• Extensible• More CPU performance• High-performance I/O• Upgrade options• Rack mountable• No side-access needs• High-availability options• Maintenance Contracts• Management Options
Select Vendors for Reliability
• More people depend on a given server than on an individual workstation, so it matters
• Talk with other SAs• Standardize on a vendor and product
line to reduce costs– Cost of knowing how to maintain– Cost of spares– Cost of wasting components when
reorganizing
Cost
• Cost per unit of performance will be higher for a server
• That cost is spread over many users• The users may be local PCs, Web
clients, or a combination
Maintenance Contracts & Spare Parts
• Non-critical: 2-day response may be OK– Development machines
• Groups of similar servers– Extensive spares kit
• Critical host: Perhaps a maint contract with same-day response– The old way of doing it
• Can you get vendor to store spares on-site?
• On-site tech
Spares
• How good is that spare on your shelf?– Do they go bad on the shelf?
• Did you re-order it when the previous one died?
• RMA – Return Material Authorization• Cross-shipping• Is that spare really bad?
– Is the “new” one really good?
Data Integrity
• Windows insists on saving some data on the local machine– Registry entries
• Good reason to image• UNIX machines have their own set of
challenges
Servers Belong in the Data Center
• Proper environment– Power– UPS– HVAC
• High-bandwidth connections to backup
• Access by techs
• Field office: Need a server closet
Client/Server Configuration
• Web: No need to be the same• UNIX: Often need the same
– Use NFS to mount server’s resources on clients, which may be diskless
– Similar situation (Citrix) available for Windows
Provide Remote Access
• KVM switch– Large versions work via Ethernet, which
requires reliable net• Remote Console• UNIX: Simple Ethernet connections
work fine, especially for command-line management
Mirror Boot Disks
• Keep a copy of the boot partition so you can get the machine up quickly if needed
• Include the tools needed for full recovery
Server Appliances
Servers sold from the outset for specific purposes
• Engineered for optimal performance• Pre-configured• May include features you can’t get
otherwise• May be locked down or otherwise
limited– Example: Almost any networking box at
Best Buy
Redundant Power Supplies
• Either “hot swap” or no reason to bother• Either power supply must have enough
power for the system• Separate power cords, plugged into
separate circuits all the way to separate breakers
• Do you need to UPS on both sides?– Probably not, since you are guarding against
different dangers– But you need to deal with down supplies quickly
Full versus n + 1 Redundancy
• n + 1 means you can handle any single failure
• Do your problems only come one at a time?
• Full redundancy may provide load sharing, which helps iron out peaks
• When using n + 1 redundancy, it is important to swap out failed components quickly before a second failure occurs– Especially important if n is a large
number
Questions About Redundancy
• Which parts are not hot-swappable– RAID controller (often the source of
problems anyhow)• Hot-Plug or Hot-Swap
– Hot-Plug: Nothing will be broken if you change, but you’ll probably have to reboot
– Hot-Swap: The software keeps on running
Separate Network for Administrative Functions
• Performance problems might lock you out
• You can’t fix it if you can’t get to it
Alternative: Many Inexpensive Servers
• Identical servers that you never move to reduce failure points
• If you manage failures well, this could save a lot of money
• Recognize that failures are part of the game• If the load can be balanced, this might be a
very scalable architecture• Disposable servers?• Opposite approach: Virtualization/Clustering
Blade Servers
• Dell sells them if you want them• Economics haven’t really panned out• Go with commodity servers instead• Or a cluster of large servers for
virtualization
Server Connectivity
Mainframe
Mainframe
TerminalController
TerminalTermin
alTerminal Terminal
A New World Begins
Mainframe
TerminalController
TerminalTermin
alTerminal Terminal
Hub
PC
Internet
More PCs
Mainframe
TerminalController
TerminalTermin
alTerminal Terminal
Hub
PCPC
PCPC
Internet
Duh…
Mainframe
TerminalController
TerminalTermin
alTerminal Terminal
Switch
PCPC
PCPC
Internet
PCPC
PCPC
The Problem Has Moved
Mainframe
TerminalController
Terminal Terminal
OrganizedNetwork
PCPC
PCPC
Internet
PCPC
PCPC
Need Speed Here
The “Final” solution
Server OrganizedNetwork
PCPC
PCPC
Internet
PCPC
PCPC
Need Speed Here
Server
The Next Wave(s)
Server OrganizedNetwork
PCPC
PCPC
Internet
PCPC
PCPC
Need Even More Speed Here
Server
Cloud Service
s
Servers become services, and can be anywhere
Everything communicates via IP
and Here
Sun Microsystems: “The network is the computer”
Convergence
• More of our corporate operations are going over the Ethernet network as time goes on.
• The network must be faster.– Performance is more difficult to predict.
• The network must be more reliable.– Failures will disable more of the
organization.
Monitor Your Servers
• Room temperature records can tell you when people were there– And when they forgot to close the door
• Humidity can be an issue• Security camera image capture?
– Digital security camera systems are far better than analog
Server Proliferation
• If you implement a server for each application, you’ll end up with an awful lot of servers– Disadvantages: Heat/Power, Support cost
• Current approach is to virtualize:– Super-server that is large and super-reliable
• Perhaps clustered– Consistent implementation of servers within that
hardware server– Control software that allows easy manipulation of
virtual servers:• Creating backup images• Migrating from one hardware server to another