> is will there be any problem in this configuration and leaving FAST cache enabled as I only have a small amount of drives so using seperate pools is probably not feasilble.
Its always prudent to separate your means of recovery from you application's filesystem. You don't want, 'all your eggs in one basket', in the unlikely event of a filesystem failure.
Also, logs are typically, small-block, sequential write. This is not an ideal I/O profile for the FAST Cache. Logs can take-up FAST Cache capacity while offering little performance benefit. The capacity they consume is better used for LUNs better suited to secondary caching.
If you only have a few drives, placing your logs on traditional LUNs is the most efficient use of drive capacity to separate the much smaller capacity log LUNs from the application filesystem. There is also the option of placing the logs onto Traditional LUNs on the system drives. They may have some spare capacity and cannot be used for pools. However, the use of the system drives will depend on the bandwidth consumed by the logs. EMC Unified Best Practices for Performance and Availability: Common Platform and O.E. Block 31.0 in its 'System drive performance provisioning section' describes the bandwidth restrictions.
jps00
2 Intern
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392 Posts
0
August 1st, 2011 05:00
> is will there be any problem in this configuration and leaving FAST cache enabled as I only have a small amount of drives so using seperate pools is probably not feasilble.
Its always prudent to separate your means of recovery from you application's filesystem. You don't want, 'all your eggs in one basket', in the unlikely event of a filesystem failure.
Also, logs are typically, small-block, sequential write. This is not an ideal I/O profile for the FAST Cache. Logs can take-up FAST Cache capacity while offering little performance benefit. The capacity they consume is better used for LUNs better suited to secondary caching.
If you only have a few drives, placing your logs on traditional LUNs is the most efficient use of drive capacity to separate the much smaller capacity log LUNs from the application filesystem. There is also the option of placing the logs onto Traditional LUNs on the system drives. They may have some spare capacity and cannot be used for pools. However, the use of the system drives will depend on the bandwidth consumed by the logs. EMC Unified Best Practices for Performance and Availability: Common Platform and O.E. Block 31.0 in its 'System drive performance provisioning section' describes the bandwidth restrictions.
HTH.
jps00
2 Intern
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392 Posts
0
August 1st, 2011 06:00
> I was thinking along the lines of a small RAID 1/0 traditional RAID group for the redo log LUNs and your explanation has helped my decision.
In my opinion, based on what you've described above, that is a good decision.
smarti2
214 Posts
0
August 1st, 2011 06:00
jps00,
Thanks for the reply.
I was thinking along the lines of a small RAID 1/0 traditional RAID group for the redo log LUNs and your explanation has helped my decision.
Pools are a good idea for simplyfying things but when you get into a more detailed design you see that you need a combination.
In addition this customer will be using Orcale ASM.
Cheers
Ian