[ Pobierz całość w formacie PDF ]
.x or another netware oper-work management.ating systemoSEE ALSO In-place upgrade, which usespSERVER.EXE to upgrade from Net-EMA (Enterprise ManagementqWare 2.x to NetWare 3.x and thenArchitecture); Network Management;uses the 4.x upgrade programs toNMA (Network Managementrcontinue the upgrade processArchitecture)sAs a verb, upgrade refers to the process ofUpgrade performing the installation of a newer soft-tware version or of a more powerful hard-An upgrade provides a mechanism for con-uware component.verting from one version of a program orpackage to another, more recent one.Forvexample, Novell supports the followingUplinkwtypes of upgrades to NetWare 4.x:In telecommunications, a communicationsxMigration, in which servers are con- link between one or more earth stations anda satellite; also, the process of transmittingverted from NetWare 2.x or 3.x toyfrom an earth station to the satellite.zNMPNMPPNM 1052 UploadCOMPAREUPS (Uninterruptible Power Supply)DownlinkA UPS is an emergency power source thatcan deliver a limited amount of power to aUploadfile server or other device in the event of aTo transfer data (such as a file) from a PCblackout (total loss of power).or other machine to a host machine.ForUPSs are sometimes known as onlineexample, the target machine may be a main-UPSs to distinguish them from SPSs (standbyframe or a bulletin board system (BBS) com-power supplies), which are also known asputer.In general, an upload transfers from aoffline UPSs.An SPS is similar, but not iden-remote machine to a central one.This pro-tical, to a UPS.The main difference is that acess requires a communications protocolUPS always supplies power through a bat-that both host and recipient can understandtery, whereas an SPS does so only whenand use.there is a power failure.UPS OperationUpper Memory Block (UMB)A UPS provides power to a file serverSEEthrough its battery and an inverter (whichUMB (Upper Memory Block)converts the battery s direct current to alter-nating current).That is, a UPS takes powerfrom the lines and uses it to charge a battery.CONSEQUENCES OF ONLINE POWERAn online power supply has several consequences:Since a server will get more than just emergency power from the UPS, the UPS must be able to providepower that is at least as clean as the power company s.In practice, this means the UPS must be able toproduce a true sine wave pattern, rather than providing just a square wave as a rough approximation.Askpotential vendors to send you typical wave patterns produced by their devices or check on these for your-self.To do that properly, you ll need an oscilloscope.There is a 25 to 30 percent loss of power as it goes through the battery and the inverter.Thus, the UPSmust work harder than the power company to supply the file server (or whatever) with its power.(Astandby power supply, in contrast, loses only about 2 percent of the power.)A busy UPS generates a considerable amount of heat as it loses the power.This heat causes wear and tearon the UPS components, including the battery.This wear shortens the effective lifetime of the compo-nents.Some manufacturers house the battery in a separate box to protect it from the heat, and therebyextend the battery s life. UPS (Uninterruptible Power Supply) 1053The UPS then feeds the server by sending and supply.See the UPS Monitoring articleapower from the battery through an inverter for more information.to create the alternating current the com- Some UPSs can perform automatic net-bputer s power supply expects.The UPS s bat- work shutdowns in case of a blackout.Thisctery is kept full by a battery charger that is is a great help because it enables networks toalso part of the UPS.be shut down properly even if no one isdA UPS with a bad battery can actually around during a power outage.Shutdownsuck power from the lines as it tries to capability is often provided in an optionalecharge the battery.This can cause voltage board that is plugged into the server (orfsags in other devices.Similarly, a UPS oper- whatever machine is being protected).ating in an environment with a low voltagegVariant Power Suppliessupply will not be able to charge the battery,which may also get drained to provide extra hThe (online) UPS and the SPS represent twopower. pure ends of a spectrum that includes var-iUPSs typically work as battery chargersious hybrids and special variants.Theseduring normal operation.If there is some-hybrids each have their own distinctive fea- jthing wrong with the battery, the UPS maytures, advantages, and disadvantages:kdraw more than its share of power, toAn online without bypass variantthe detriment of other equipment on theloperates like a regular UPS, except thatsame line
[ Pobierz całość w formacie PDF ]