An EMC Avamar customer is unable to successfully complete a nightly backup of a large file
server within their defined backup window. The server is a single quad core system with 2 GBs of
RAM. The file system data is being stored on a RAID 5 SAN disk.
Currently, the server has 7 million files totaling 1 TB of data spread across three volumes. The
Avamar agent was installed and configured using the default settings.
What should be recommended to increase the performance of the nightly backup?
A.
Increase the size of the local file cache
B.
Migrate the data volumes to RAID 1/0 disks
C.
Increase the speed of the network connection
D.
Increase the size of the local hash cache
If you need to limit the sizes of the caches below the optimum values:
• For a typical file server, first allocate the required RAM to the file cache.
• For a typical database client, first allocate the required RAM to the hash cache.
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La respuesta correcta es la alternativa A.
En este caso, la regla para el dimensionamiento de la memoria caché es 1/8 del total de la memoria RAM en el caso de Archivos y de 1/16 del total de la memoria RAM en el caso de bases de datos.
La regla para calcular si la caché configurada por defecto, en el caso de archivos es asignar 44 MB por cada millon de archivos.
44*7 = 308 MB.
2048 MB =2 GB RAM.
Caché por defecto para fIles, 1/8 de la ram.
2048/8 = 256 MB RAM.
Según lo anterior, el memoria caché es insuficiente. Respuesta correcta A.
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the correct answer is not A
file cache size required:
7 million * 44MB = 308MB
max file cache that can be configured(1/8 of RAM):
2048MB/8 = 256MB,
and as file cache starts from 2.75MB and only doubles when increasing the size , the max allowed size is 176MB which is the value below 256MB.
that said, file cache can’t be increased because you can’t exceed the max limit of the file cache which is 1/8 of RAM(176MB in our case) otherwise you will have performance issues.
what needs to be increased is the RAM itself to be able to increase the file cache, but that choice is not available in the answers,
so I would say the right answer is B, as this is the other bottleneck mentioned in the question which is having the data on RAID 5.
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