Microsoft Word Hardware Reconfiguration Methodology V final2

Speed and bandwidth

It is important to determine the network speed, amount of time available and required by the tool, and required network bandwidth. Time constraints will also be a determining factor in determining which backup utility to use. Consider the following:

1. 
   Tar and Cpio are very fast when backing up small to medium-sized datasets. Dump is very fast for medium to large-sized datasets. DD is not fast because it must copy every bit of data from a partition or raw device.
   

2. 
   How much network bandwidth is available? Does it decrease during the day and increase at night or on weekends? If so, then backups should be scheduled when network bandwidth is at highest.
   

3. 
   If backups must be performed during periods of high network utilization, then data compression tools can be used to help reduce the amount of required network bandwidth. The data stream can be compressed using SSH, Gzip, Zip, or Bzip2 before being sent and decompressed at the remote system.
   

4. 
   If DD must be used then it will typically require more network transmission time as bit- copies are larger than their counterpart backup types. Thus, DD-based backups should be compressed and backed up during periods of low network utilization.
   

5. 
   What is the read/write speed of the archival media and/or device? This could be the backup process’ bottleneck. Spreading the backup from multiple partitions/filesystems across multiple backup devices (local or remote) could significantly speed up the backup. However, this is not a useful option for multivolume backups; instead, it is better suited for simultaneously backing up multiple datasets.
   

6. 
   Local backup devices are usually faster than remote devices and using multiple backup devices simultaneously for large datasets from different partitions is faster than using a single backup device, whether local or remote.
   

7. 
   SCSI devices are generally faster than IDE devices and are therefore highly suggested.
   
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