Quantum 6-01376-05 Benutzerhandbuch

  StorNext File System Tuning

The Metadata Controller System

StorNext File System Tuning Guide

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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 

 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 

 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

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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 

 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