StorNext File System Tuning The Underlying Storage System
RAID Cache
Configuration
The single most important RAID tuning component is the cache configuration. This is particularly true for small I/O operations. Contemporary RAID systems such as the EMC CX series and the various Engenio systems provide excellent small I/O performance with properly tuned caching. So, for the best general purpose performance characteristics, it is crucial to utilize the RAID system caching as fully as possible.
For example,
However, there are a few drawbacks to consider as well. For example,
Caution: Some RAID systems cannot safely support
| Consequently, this is an area that requires an understanding of |
| application I/O requirements. As a general rule, RAID system caching is |
| critically important for most applications, so it is the first place to focus |
| tuning attention. |
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RAID | |
Caching | operations. This is accomplished by returning a successful reply as soon |
| as data is written into cache, and then deferring the operation of |
| |
| actually writing the data to the physical disks. This results in a great |
| performance improvement for small I/O operations. |
| Many contemporary RAID systems protect against |
| loss due to power or component failure. This is accomplished through |
| various techniques including redundancy, battery backup, battery- |
| backed memory, and controller mirroring. To prevent data corruption, it |
| is important to ensure that these systems are working properly. It is |
| particularly catastrophic if file system metadata is corrupted, because |
| complete file system loss could result. Check with your RAID vendor to |
| make sure that |
| Minimal I/O latency is critically important for metadata stripe groups to |
| achieve high metadata operations throughput. This is because metadata |
2 | StorNext File System Tuning Guide |