Disk I/O

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Non-Volatile Memory Express Performance with Linux on IBM LinuxONE Emperor II and LinuxONE Rockhopper II

Results of Use Cases

Abstract

The high performance characteristics of NMVe storage have the potential to improve response times and throughput of I/O intense use cases. The expectation is that in servers where NVMe storage is large enough to contain all data NVMe will be a fast and inexpensive storage. This could improve the performance of databases, Docker containers and KVM host and guests. In case the NVMe storage is too small to contain all data NVMe might accelerate I/O intense functions of databases. This paper will demonstrate the advanced performance when using NMVe storage with a set of performance comparisons for certain use cases.

View Non-Volatile Memory Express Performance with Linux on IBM LinuxONE Emperor II and LinuxONE Rockhopper II

Creation date September 2018

Linux on z Systems Disk I/O Performance

Presentation abstract

In many Linux on z Systems servers the disk attachment is not optimized to get best throughput. While default settings may be sufficient for disks with low or moderate I/O rates it can be useful to consider this information for disks where higher I/O rates are expected. The material can be used as a check list to review existing or future server configurations.

It describes tuning knobs on all layers
  • Application program
  • Linux kernel / device drivers
  • Interconnects
  • Storage server
  • Linux guests on z/VM and KVM
  • KVM host
  • z14 performance benefits

View Linux on z Systems Disk I/O Performance

Creation date October 2017

QSAM access method for data sharing with z/OS

Presentation abstract

So far, the access of z/OS data from Linux on z Systems required the use of a network interface and tools, such as NFS or FTP.

With QSAM a method is introduced to directly access storage devices in PS/PDS format.

The presentation shows benefits and prerequisites of this very efficient way to read z/OS data from Linux on z Systems.

View QSAM access method for data sharing with z/OS

Creation date February 2015

Linux I/O scheduler performance evaluation

Presentation abstract

To check if previous results of I/O Scheduler analyses are still valid, we re-evaluated this subject. For this evaluation, the cfq, deadline and noop I/O schedulers were compared on different workload scenarios and with different distributions.

View Linux I/O scheduler performance evaluation

Creation date October 2013

High performance FICON

Presentation abstract
  • Prerequisites to enable High Performance FICON (HPF) with Linux on z Systems
  • Performance expectation
  • Performance results and comparison of channel programs with chained 4KB data, channel programs with full track data and HPF

View High performance FICON (283KB)

Creation date July 2010

ECKD versus SCSI

Presentation abstract
  • Linux kernel components involved in disk I/O: block device layer and device drivers
  • Example for storage server attachment
  • I/O processing differences between ECKD and SCSI
  • Sample scenarios for ECKD, including single disk, Parallel Access Volumes (PAV) , striped logical volume and storage pool striped volume
  • Sample scenarios for SCSI, including single disk, multipathing, striped logical volume and storage pool striped volume

View ECKD versus SCSI (540KB)

Creation date July 2010

DASD block size

Presentation abstract

The DASD block size recommendation is 4096 bytes. The presentation shows that throughput and capacity is lower with smaller block sizes.

View DASD block size (267KB)

Creation date June 2010

Linux disk I/O considerations

Presentation abstract
  • Recommendation for using journaling file systems
  • How to deal with temporary files
  • Direct I/O
  • Async I/O
  • Function and recommendation for I/O schedulers
  • Linear and striped logical volumes
  • Effect of read ahead settings
  • Monitoring disk I/O with iostat

View Linux disk I/O considerations (291KB)

Creation date June 2010

Disk performance optimizing

Presentation abstract
  • Storage server internals that need to be considered
  • Strategy for better use of ranks, device adapters, host bus adapters and channel paths
  • Disk placement

View Disk performance optimizing (364KB)

Creation date June 2010

Storage pool striping

Presentation abstract

This presentation explains storage pool striping, shows its impact on performance, and compares the performance of storage pool striped volumes with logical volumes.

View Storage pool striping (261KB)

Creation date March 2009