Quantum StorNext QD7000, Руководство по оборудованию

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• The smaller the bandwidth on the WAN, the longer it takes a mirror to synchronize.
• If the bandwidth does not exceed the average rate, you might not be able to synchronize the data
at all. For example, if the system writes at 1 Mb/s, it needs 2 Mb/s of bandwidth available.
• If the mirroring is lagging far behind during production hours, suspend the mirror. During off-
peak hours, resume the mirror.
• If you need to keep the Synchronous Mirroring on at all times, keep the mirror physically as close
as possible to the production site.
• To determine the average write rate, you should use the available system utilities and should take
measurements during peak times.
• If you anticipate adding any applications, determine the bandwidth needs for any future
applications.
• Acceptable lag times vary depending on the environment and should be determined on an
individual basis.
Line capacities
Line type Capacity in Mb/s Speed in MB/s
T-1 1.544 0.193
T-3 43.232 5.404
OC-3 155.6352 19.454
OC-12 622.5408 77.8176
OC-48 2490.1632 311.27
OC-192 9960.6528 1245.085
The following table shows average write operations in Mb/s with corresponding line capacity
calculations. When the line capacity calculation is below 50 percent, the result is an adequate
response-time performance and a limited need for delta logging (when the mirror lags behind the
data). When the line capacity calculation is above 50 percent, the mirror can never catch up. Any
transfers above 50 percent will start to lag.
Average write time
in Mb/s T-1 T-3 OC-3 OC-12 OC-18 OC-192
0.01 5.2% 0.2% 0.1% 0.0% 0.0% 0.0%
0.1 51.8% 1.9% 0.5% 0.1% 0.0% 0.0%
1 518.1% 18.5% 5.1% 1.3% 0.3% 0.1%
10 5181.3% 185.3% 51.4% 12.9% 3.2% 0.8%
Hardware installation for Synchronous Mirroring and Asynchronous Mirroring | 129