Tekram Technology DC-820B manual Eisa Fast Scsi Caching Adapter

EISA Fast SCSI Caching Adapter

Mirrored to SCSI ID: NO/1-7. This disk mirroring function is implemented by the DC-820B’s firmware and works for all operating systems. This option needs two and only two drives and is selected from the slave drive’s point of view. The SCSI ID number you choose stands for the master drive that you want to mirror to. The NO option may stand for two meanings: either this drive (master) mirrors to another drive or no mirroring operation is on this drive at all. So, from the example shown on the setup screen, we can tell that the fixed drive with SCSI ID 1 (slave) is mirrored to another fixed drive with SCSI 0 (master). The MO with SCSI ID 2 has NO as its option and is not involved in any mirroring activity.

When the mirror function is enabled, the mirror-pair related to this operation would be seen as one. That means a WRITE operation would be performed on both the master and slave drives. On the other hand, a read operation would only access the data from the master drive and not the slave. Since a duplicate copy of the master drive would reside on the slave drive, data security is ensured in case one of the pair is damaged. One condition of this option is that the slave drive must have at least the same storage capacity as the master drive. Besides setting this option properly, you still have to run a

utility program (TOOLBME.EXE) to set up the mirroring initialization. Refer to the next section for more details about TOOLBME.EXE.

BIOS INT 13H device: HD/HDRM/No. HD (default) option is for fixed disk drives controlled by BIOS INT 13H and will be ignored if no device is installed. HDRM option is for fixed disk and removable disk drives con- trolled by BIOS INT 13H. The No option is for drives controlled by the DC- 820B’s device driver instead of INT 13H. Note that removable disk drives with the HDRM option selected can only function as fixed disks and are not allowed to change media. Also, if you set the option as HD for a removable media device, it can only be recognized by adding a device driver instead of being controlled through BIOS INT 13H.

MAX Sync Xfer rate: 10.0 - 2.00 MB/sec. DC-820B supports the 10.00 MB/sec as its highest data transfer rate to work with SCSI devices comply- ing with Fast SCSI protocol. The DC-820B will negotiate an optimum speed depending on the transfer rate of each device under your chosen option.

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