Server+ Exam Notes

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11. Given below are important bus types and their characteristics:

Bus Type	Data bus width	Speed	Bandwidth	Comments
ISA	16-bit	8.3MHz	15.9MBPS	Use jumpers to configure
EISA	32-bit	8.3MHz	31.8MBPS	Backward compatible with ISA, uses software/ jumpers for configuration
VESA or VL bus	32-bit	33MHz	127.2MBPS	Backward compatible with ISA cards
PCI	32-bit	33MHz	127.2MBPS	Supports Plug and Play
64-bit PCI	64-bit	66MHz	508.6MBPS	Supports Plug and Play

12. Disk swapping:

1. Cold Swap: It means that you have to power down a server before the part is replaced.
2. Warm Swap: It means that you may have to stop I/O functions corresponding to the part that need to be replaced by using appropriate commands. The server need not be powered off.
3. Hot Swap: Hot Swap allows the faulty part to be replaced without interrupting the Server or introducing any interruption in the I/O procedures.

Obviously, hot-swap allows for easy replacement of faulty part.

13. EEPROM is used to program dynamically, whereas, EPROM can be erased with ultra violet light and reprogrammed.

14. Usually, a sector contains 512 bytes. To find out the size of a hard disk, use the formula:

(# of cylinders X # of sectors X # of heads) X 0.5 KB

15. MCA architecture is a proprietary architecture.

16. Cable Select, if enabled, determines which drive is the master and which drive is the slave when there are two IDE hard disks.

17. IDE/ATA/ATAPI:

- In the ATA/ATAPI-4 standard / Ultra DMA transfer, a 80-conductor (wires) IDE/ATA cable is used. However, it does not have 80 pins on each connector, just 40. This means that the new cable is pin-compatible with the old drive. The additional conductors(40) are introduced to reduce the cross talk / interference between the conductors and are grounded.

The old IDE/ATA cable has only 40 conductors.

- The first implementation of Ultra DMA as specified in the ATA/ATAPI-4 standard, included three Ultra DMA modes, providing up to 33 MB/s of throughput. Ultra ATA/66 refers to an interface speed of 66MB/Sec. Similarly, Ultra ATA/100 refers to an interface speed of 100MB/Sec.

- A maximum of two IDE disk drives can be connected to each IDE/ATA controller. Since most computers come with two IDE controllers, we can connect a maximum of 4 IDE hard drives.

- IDE/ATA hard disk interface does not require any external cable termination. Whereas, SCSI requires cable termination on both ends.

- IDE hard drives come with a 40 pin connector. SCSI hard drives come with different types of connectors, but not 40 pin connector.

Some of widely used SCSI connectors are:

Centronics type 50-pin connector (old type)

50 pin high density connector

68 pin high density connector

However, all ATA/IDE connectors are 40 pin.

- The disk drive designations in an ID/ATA chain is Master and Slave. These are selectable by changing the jumpers on the disk drives or can be made cable select. If both the hard disks are jumpered for Master or if both hard disks are jumpered for Slave configuration, your computer may fail to boot!

18. There can be a maximum of only two devices that can be connected on a single channel of an ATA/IDE system. In a SCSI bus system, you can connect 7 or 15 or more devices to a SCSI channel (excluding SCSI controller itself). The number of disks (or devices) that can be connected to an IDE channel is a major factor to be considered when planning the disk drive. SCSI allows you to attach a large collection of add-on peripherals like CD recorders, tape drives both inside and outside the case. EIDE/ATA is strictly for devices inside the PC / SERVER case.

19. Clustering:

- To configure a clustered server environment, at least 2 servers are required.

- All the following are true about clustering:

Clustering improves the availability of the network.

Processing load is distributed among the clustered servers.

Clustering allows for better scalability.

If one of the servers in a cluster fails, other server(s) in the cluster take over the entire load of the failed server without interruption to the services.