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freenas的文档
1.3.2 RAM
The best way to get the most out of your FreeNAS® system is to install as much RAM as possible. If
your RAM is limited, consider using UFS until you can afford better hardware. FreeNAS® with ZFS
typically requires a minimum of 8 GB of RAM in order to provide good performance and stability. The
more RAM, the better the performance, and the FreeNAS® Forums provide anecdotal evidence from
users on how much performance is gained by adding more RAM. For systems with large disk capacity
(greater than 8 TB), a general rule of thumb is 1 GB of RAM for every 1 TB of storage. This post
describes how RAM is used by ZFS.
It is possible to use ZFS on systems with less than 8 GB of RAM. However, FreeNAS® as distributed
is configured to be suitable for systems meeting the sizing recommendations above. If you wish to use
ZFS on a smaller memory system, some tuning will be necessary, and performance will be (likely
substantially) reduced. ZFS will automatically disable pre-fetching (caching) on systems where it is not
able to use at least 4 GB of memory just for ZFS cache and data structures. This post describes many of
the relevant tunables.
If you plan to use ZFS deduplication, a general rule of thumb is 5 GB RAM per TB of storage to be
deduplicated.
If you use Active Directory with FreeNAS®, add an additional 2 GB of RAM for winbind's internal
cache.
If you are installing FreeNAS® on a headless system, disable the shared memory settings for the video
card in the BIOS. |
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