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StorNext File System Tuning
The Metadata Controller System
StorNext File System Tuning Guide 10
StripeBreadth 0
This setting must match the RAID stripe size or be a multiple of the RAID
stripe size. Matching the RAID stripe size is usually the most optimal
setting. However, depending on the RAID performance characteristics
and application I/O size, it might be beneficial to use a multiple of the
RAID stripe size. For example, if the RAID stripe size is 256K, the stripe
group contains 4 LUNs, and the application to be optimized uses DMA I/
O with 8MB block size, a
StripeBreadth setting of 2MB might be optimal.
In this example the 8MB application I/O is issued as 4 concurrent 2MB I/
Os to the RAID. This concurrency can provide up to a 4X performance
increase. This typically requires some experimentation to determine the
RAID characteristics. The
lmdd utility can be very helpful. Note that this
setting is not adjustable after initial file system creation.
Example:
[stripeGroup AudioFiles]
Status UP
Exclusive Yes ##These two lines set Exclusive stripeGroup ##
Affinity AudioFiles ##for Audio Files Only##
Read Enabled
Write Enabled
StripeBreadth 1M
MultiPathMethod Rotate
Node CvfsDisk4 0
Node CvfsDisk5 1
BufferCacheSize 0
This setting consumes up to 2X bytes of memory times the number
specified. Increasing this value can reduce latency of any metadata
operation by performing a
hot cache access to directory blocks, inode
information, and other metadata info. This is about 10 to 1000 times faster
than I/O. It is especially important to increase this setting if metadata I/O
latency is high, (for example, more than 2ms average latency). We
recommend sizing this according to how much memory is available;
more is better.
Example:
# BufferCacheSize 64M # default 32MB