IBM E16RMLL-I - Tivoli Storage Manager, Руководство по внедрению

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IBM Tivoli Storage Manager Implementation Guide
requirements, and therefore, the calculation may not be linear. In any case, keep
in mind that it is best to assume a middle case/worst case scenario so that you
do not run out of tapes.
Backup tapes
To calculate the number of on-site tape volumes required for backup operations,
carry out the following calculations:
1. If this is a sequential storage pool (tape device), multiply the primary storage
pool size by the number of backup versions from Table 2-5 on page 26 to give
versions pool size.
2. Add the sum of all Total storage used fields for each client from Table 2-1 on
page 18 to the versions pool size, giving tape pool size.
3. Divide the tape pool size by the device capacity to find the number of tape
cartridges required.
4. Add 50% to cater to tapes that are in filling status to give the total cartridges
required for on-site tapes.
5. If using collocation, normally there should be at least as many tape cartridges
as there are clients. Consider tape native capacity as a rounding factor.
We do not use the compressed capacity of the tape here because we factored
the client compression rate into the calculation of the storage pool size. If data is
compressed at the client, it will not receive any benefit from hardware
compression done by the tape drive.
Backup tape calculation
To calculate:
1. If the primary storage pool is 254 GB, and the number of versions kept is 7,
then multiplying 1.04 * 7 gives a 1778 GB versions pool size.
2. If the all the clients are using 1200 and 400 GB, then 1200 + 400 + 1778
equals 3378 GB.
3. If the tape device has a capacity of 400 GB, then dividing 1938 by 400 gives 9
cartridges required to store all the data.
4. 5 * 1.5 gives 14 total cartridges required for on-site tapes.
5. If we use collocation for the database servers, since there 4 database servers
and 20 file servers, we have enough tape volumes.