Summer 2009 IntroductionCNT 4603, Summer 2009: Introduction+ A practical hands-on approach+ Also higher-level concepts+ Expertise is distributed: system administration happenseverywhere from your PC to large servers, and systemadministration is generally collaborative. Other peoplewill help you solve problems and learn moreCNT 4603Summer 2009 IntroductionCNT 4603, Summer 2009: Introduction+ The systems we will emphasize are Linux. We will alsotalk some about Solaris and Windows.CNT 4603Summer 2009 IntroductionCNT 4603, Summer 2090: Introduction+ You may see occasionally see these abbreviations incourse materials:ó LAH → Linux Administration Handbook, 2nd Ed(Nemeth et al)ó W2K8 → Windows Server 2008: NetworkingFoundations (Minasi et al)CNT 4603Summer 2009 IntroductionASSIGNMENT+ Read chapters 1, 2, and 3 in LAH+ Read chapters 1, 2, and 3 in W2K8CNT 4603Summer 2009 IntroductionIntroduction to Unix+ Unix is now more than 30 years old+ It began in 1969+ See The Evolution of the Unix Time-sharing Systemby Dennis Ritchie+ http://cm.bell-labs.com/cm/cs/who/dmr/hist.htmlCNT 4603Summer 2009 IntroductionIntroduction to Unix+ Started at AT&T’s Bell Labs, derived fromMULTICS.+ Initial hardware was a DEC PDP-7, and the filesystemwas hierarchical but did not have pathnames+ (i.e., there was no equivalent to a pathname suchas /etc/hosts, it would just be hosts; directoryinformation was kept in a special file called dd)CNT 4603Summer 2009 IntroductionIntroduction to Unix+ Rather than a product from a manufacturer, Unixbegan as collaboration with these goals:ó Simplicityó Multi-user supportó Portabilityó Universities could get source code easilyó Users shared ideas, programs, bug fixesCNT 4603Summer 2009 IntroductionIntroduction to Unix+ The development of early Unix was user-driven ratherthan corporate-driven+ Note that Linux and the BSDs (FreeBSD,OpenBSD, NetBSD) now flourish in similiar“open source” environments (http://www.freebsd.org,http://www.openbsd.org, http://www.netbsd.org)CNT 4603Summer 2009 IntroductionIntroduction to UnixThe first meeting of the Unix User Group was inMay, 1974; this group would late become the UsenixAssociationYou can watch the ever-varying open source world ofLinux/BSD distributions at http://www.distrowatch.comCNT 4603Summer 2009 IntroductionA History of Unix+ In the beginning, processes were very different+ Originallyó Each terminal only could have one active processó When creating a “child” process, the parent firstclosed all of its open filesó Then the parent linked to the executable and openeditCNT 4603Summer 2009 IntroductionA History of Unixó Then the parent copied a bootstrap to the top ofmemory and jumped into the bootstrapó The bootstrap copied the code for the new processover the parent’s code and then jumped into itó When the child did an exit, it first copied in the parentprocess code into its code area, and then jumped backinto the parent code at the beginningCNT 4603Summer 2009 IntroductionOld Unix+ Today the parent uses a fork/exec/wait model:ó fork(2) (to create a new child process)ó exec*(2) (to have the child process start executinga new program)ó wait*(2) (to wait on the child (or at least checkon its status if non-blocking))CNT 4603Summer 2009 IntroductionLinux: a complete Unix-compatibleoperating system+ Runs on huge array of hardware, from IBM’s biggestmachines down to commodity routers such as theLinksys WRT routers using DD-WRT+ Based on Linux Torvalds’ kernel (he is still in charge ofkernel development (2.6.28 is the current stable release),though now many people work on the kernel)CNT 4603Summer 2009 IntroductionLinux: a complete Unix-compatibleoperating system+ The Linux distributions we will use are CentOS andFedora; each includes a full development environment,X-Windows, NFS, office environment products (wordprocessors, spreadsheets, etc), C, C++, Fortran, severalmail systems (exim, postfix, and sendmail) and wholelot more (a full install is around 5 to 7 gigabytes)+ Linux is mostly POSIX.1 compliantCNT 4603Summer 2009 IntroductionLinux: a complete Unix-compatibleoperating systemFAQ: http://www.opengroup.org/austin/papers/posix faq.htmlCNT 4603Summer 2009 IntroductionSolarisSolaris is a vendor UnixIt runs on Sun custom hardware and commodity PC hardware –and in virtual environmentsCNT 4603Summer 2009 IntroductionMicrosoft Windows+ Windows 2008 Server is a proprietary system that follows in theNT and Windows Server 2003 family+ Windows 2008, like Windows 2003, has several varieties:ó “Standard Edition” (Supports “Server Core”)ó “Enterprise Edition” (Supports “Server Core”)ó “Datacenter Edition” (Supports “Server Core”)ó “Windows Web Server”ó “Windows Storage Server”CNT 4603Summer 2009 IntroductionMicrosoft Windows+ The Minasi book is an enjoyable, and no longer volumninous, read+ Windows has the advantage that it provides a single vendorsolution, completely controlled by MicrosoftCNT 4603Summer 2009 IntroductionSystem administration responsibilities(AIC)+ Availability of services and data+ Integrity of services and data+ ConfidentialityCNT 4603Summer 2009 IntroductionSystem administration duties+ Installing new hardware and software+ Updating and upgrading hardware and software+ Monitoring for problems+ Resolving problemsCNT 4603Summer 2009 IntroductionSystem administration duties+ Planning for growth and obsolence+ Making backups+ Recovering data from backupsCNT 4603Summer 2009 IntroductionAvailability+ Lack of availability can have a large dollar impact on manybusinesses+ The most common danger to availability is SPOFs (single pointsof failure)CNT 4603Summer 2009 IntroductionAvailability+ SPOFs are generally cured by redundancy. Redundancy models:ó Cold → Good points: “guarantees” availability, but (1) typicallymost expensive (2) tends to require frequent testing (3) typicallyslow to bring liveCNT 4603Summer 2009 IntroductionAvailabilityó Warm (dual-use hardware that is powered up and used forrelated but non-production purposes such as development or q/a)→ Typically good availability and less expensive than cold since thehardware has day-to-day use, but (1) tends to be one-offish and (2)tends to require frequent testing of switchoverCNT 4603Summer 2009 IntroductionAvailabilityó Hot (redundant hardware in production) typically least expensivesince it is in active production use and testing requirements tendto be less but more likely to have capacity