Quantum 6-01376-05 manual StorNext File System Tuning Metadata Controller System

Page 17

StorNext File System Tuning

The Metadata Controller System

The cvcp utility is a higher performance alternative to commands such as cp and tar. The cvcp utility achieves high performance by using threads, large I/O buffers, preallocation, stripe alignment, DMA I/O transfer, and Bulk Create. Also, the cvcp utility uses the SNFS External API for preallocation and stripe alignment. In the directory-to-directory copy mode (for example, cvcp source_dir destination_dir,) cvcp conditionally uses the Bulk Create API to provide a dramatic small file copy performance boost. However, it will not use Bulk Create in some scenarios, such as non-root invocation, managed file systems, quotas, or Windows security. Hopefully, these limitations will be removed in a future release. When Bulk Create is utilized, it significantly boosts performance by reducing the number of metadata operations issued. For example, up to 20 files can be created all with a single metadata operation. For more information, see the cvcp man page.

The cvmkfile utility provides a command line tool to utilize valuable SNFS performance features. These features include preallocation, stripe alignment, and affinities. See the cvmkfile man page.

The Lmdd utility is very useful to measure raw LUN performance as well as varied I/O transfer sizes.

The cvdbset utility has a special “Perf” trace flag that is very useful to analyze I/O performance. For example: cvdbset perf

Then, you can use cvdb -gto collect trace information such as this:

PERF: Device Write 41 MB/s IOs 2 exts 1 offs 0x0 len 0x400000 mics 95589 ino 0x5

PERF: VFS Write EofDmaAlgn 41 MB/s offs 0x0 len 0x400000 mics 95618 ino 0x5

The “PERF: Device” trace shows throughput measured for the device I/ O. It also shows the number of I/Os into which it was broken, and the number of extents (sequence of consecutive filesystem blocks).

The “PERF: VFS” trace shows throughput measured for the read or write system call and significant aspects of the I/O, including:

•Dma: DMA

•Buf: Buffered

•Eof: File extended

•Algn: Well-formed DMA I/O

•Shr: File is shared by another client

•Rt: File is real time

StorNext File System Tuning Guide

14

Page 16 Page 18
Image 17
Page 16 Page 18
Contents 01376-05 Copyright Statement Contents Underlying Storage System StorNext File System TuningRAID Cache Configuration RAID Write-Back Caching RAID Read-Ahead Caching RAID Level, Segment Size, and Stripe Size Buffer Cache File Size Mix and Application I/O CharacteristicsDirect Memory Access DMA I/O Transfer NFS / Cifs Metadata Controller System Metadata NetworkStripe Groups FSM Configuration File SettingsAffinities ExampleBufferCacheSize StripeBreadth ThreadPoolSize InodeCacheSize ForcestripeAlignment FsBlockSizeSnfs Tools JournalSizeStorNext File System Tuning Metadata Controller System StorNext File System Tuning Metadata Controller System StorNext File System Tuning Metadata Controller System MountCommandOptions StorNext File System Tuning Metadata Controller System Snfs External API Hardware ConfigurationDistributed LAN Disk Proxy Networks StorNext File System Tuning Guide Network Configuration and Topology SAN Windows Memory Requirements Distributed LAN ServersStorNext File System Tuning Windows Memory Requirements StorNext File System Tuning Windows Memory Requirements Sample FSM Configuration File MAXStripeBreadth StorNext File System Tuning Sample FSM Configuration File StorNext File System Tuning Sample FSM Configuration File StorNext File System Tuning Sample FSM Configuration File
Top Page Image Contents