IBM Systems magazine, IBM Z - May/June 2020 - 35

TECHBITS

FCP
ECKD
VS

Linux on IBM Z and IBM LinuxONE: When to Use SCSI
Versus DASD Storage

B

* Reduced SAP utilization
I/O (QDIO) device driver. With
* Improved response time
QDIO, I/O operations are affected
* Server cycle reduction
using a signal adapter instruction
(SIGA). The SIGA is processed by
the System Assist Processor
Storage Efficiency
(SAP) in much the same
DASD was first introduced
way a CCW is processed
with the IBM System/360.
by the SAP. However,
It's not native to Linux.
the SIGA effectively
Linux expects to
passes a pointer to
read and write data
LEARN MORE
the data because
as 512-byte blocks,
about SCSI and DASD
the data already
but DASD devices
storage in the full article
occupies internal
use tracks (4K-byte
at bit.ly/2SqnO2k.
storage. So, while
blocks) and cylinders.
the SAPs themselves
This disparity means some
enhance I/O processing, this
conversion or emulation must
is leveled out for FCP and SCSI by:
occur to make Linux compatible
with DASD devices, and this has
I/O Channel Path and SAPs
* A 20% improvement in
a cost.
FICON I/O is driven by the channel
performance versus non-QDIO
Traditional DASDs (such as 3390
command word (CCW), whereas
mode
devices) have a maximum size
FCP is driven by the queued direct
of 65,520 cylinders. An extended
address volume (EAV) DASD device
Tak Chin is a senior programmer at IBM. He's PCC technical lead for z/VM, KVM on
can hold up to 1,182,006 cylinders,
IBM Z and Linux on IBM Z.
usinesses that run
IBM z/OS® on IBM Z® use
direct access storage device (DASD), implemented using
Extended Key Count Data (ECKD)
and FICON protocol1. But when
clients implement LinuxONE or
Linux® on IBM Z, they now have
other storage options2, the most
common being SCSI devices using
Fibre Channel Protocol (FCP). The
IBM Z platform can support DASD,
SCSI or both at once. So, which is
a better option for LinuxONE or
Linux on IBM Z? The answer varies for every business.

IBMSYSTEMSMAG.COM MAY/JUNE 2020 | 35


http://www.bit.ly/2SqnO2k http://www.IBMSYSTEMSMAG.COM

IBM Systems magazine, IBM Z - May/June 2020

Table of Contents for the Digital Edition of IBM Systems magazine, IBM Z - May/June 2020

Table of Contents
Editor's Desk: Enabling your success in a hybrid multicloud world
Currents: Arvind Krishna elected IBM CEO, James Whitehurst elected president
Currents: Solutions
Currents: Sustainable battery composition
Currents: The next generation of IBMers on why IBM Z is relevant
Currents: Women in IT value community and mentorship
Currents: A call to all Canadian mainframers
Partner POV: Develop an effective package management strategy to streamline DevOps
Cover Story: Meet the New IBM z15 and IBM LinuxONE III Models: The latest air-cooled systems can help enhance resiliency, security and availability in a hybrid cloud world
The Business Value of the Transformative IBM Z Platform How Feature 1: The Business Value of the Transformative IBM Z Platform: How IBM Z provides tools and capabilities for digital transformation
TECH Showcase: The IBM DS8900F family of flash storage systems provides improved encryption, disaster recovery, uptime and scalability
Techbits: Linux on IBM Z and IBM LinuxONE: When to use SCSI versus DASD storage
Techbits: Application tier considerations for moving to the cloud or x86
Techbits: Ask the expert: How can I reduce risk when performing an IBM Z hardware upgrade?
Beyond the Box: IBMer David Hilliard on his role as a locomotive engineer for the Catskill Mountain Railroad
IBM Systems magazine, IBM Z - May/June 2020 - Intro
IBM Systems magazine, IBM Z - May/June 2020 - Table of Contents
IBM Systems magazine, IBM Z - May/June 2020 - Cover2
IBM Systems magazine, IBM Z - May/June 2020 - 1
IBM Systems magazine, IBM Z - May/June 2020 - 2
IBM Systems magazine, IBM Z - May/June 2020 - 3
IBM Systems magazine, IBM Z - May/June 2020 - 4
IBM Systems magazine, IBM Z - May/June 2020 - 5
IBM Systems magazine, IBM Z - May/June 2020 - Editor's Desk: Enabling your success in a hybrid multicloud world
IBM Systems magazine, IBM Z - May/June 2020 - 7
IBM Systems magazine, IBM Z - May/June 2020 - Currents: Solutions
IBM Systems magazine, IBM Z - May/June 2020 - Currents: The next generation of IBMers on why IBM Z is relevant
IBM Systems magazine, IBM Z - May/June 2020 - Currents: Women in IT value community and mentorship
IBM Systems magazine, IBM Z - May/June 2020 - 11
IBM Systems magazine, IBM Z - May/June 2020 - 12
IBM Systems magazine, IBM Z - May/June 2020 - 13
IBM Systems magazine, IBM Z - May/June 2020 - Currents: A call to all Canadian mainframers
IBM Systems magazine, IBM Z - May/June 2020 - 15
IBM Systems magazine, IBM Z - May/June 2020 - Partner POV: Develop an effective package management strategy to streamline DevOps
IBM Systems magazine, IBM Z - May/June 2020 - 17
IBM Systems magazine, IBM Z - May/June 2020 - Cover Story: Meet the New IBM z15 and IBM LinuxONE III Models: The latest air-cooled systems can help enhance resiliency, security and availability in a hybrid cloud world
IBM Systems magazine, IBM Z - May/June 2020 - 19
IBM Systems magazine, IBM Z - May/June 2020 - 20
IBM Systems magazine, IBM Z - May/June 2020 - 21
IBM Systems magazine, IBM Z - May/June 2020 - 22
IBM Systems magazine, IBM Z - May/June 2020 - 23
IBM Systems magazine, IBM Z - May/June 2020 - The Business Value of the Transformative IBM Z Platform How Feature 1: The Business Value of the Transformative IBM Z Platform: How IBM Z provides tools and capabilities for digital transformation
IBM Systems magazine, IBM Z - May/June 2020 - 25
IBM Systems magazine, IBM Z - May/June 2020 - 26
IBM Systems magazine, IBM Z - May/June 2020 - 27
IBM Systems magazine, IBM Z - May/June 2020 - 28
IBM Systems magazine, IBM Z - May/June 2020 - TECH Showcase: The IBM DS8900F family of flash storage systems provides improved encryption, disaster recovery, uptime and scalability
IBM Systems magazine, IBM Z - May/June 2020 - 30
IBM Systems magazine, IBM Z - May/June 2020 - 31
IBM Systems magazine, IBM Z - May/June 2020 - 32
IBM Systems magazine, IBM Z - May/June 2020 - 33
IBM Systems magazine, IBM Z - May/June 2020 - 34
IBM Systems magazine, IBM Z - May/June 2020 - Techbits: Linux on IBM Z and IBM LinuxONE: When to use SCSI versus DASD storage
IBM Systems magazine, IBM Z - May/June 2020 - 36
IBM Systems magazine, IBM Z - May/June 2020 - Techbits: Application tier considerations for moving to the cloud or x86
IBM Systems magazine, IBM Z - May/June 2020 - 38
IBM Systems magazine, IBM Z - May/June 2020 - Techbits: Ask the expert: How can I reduce risk when performing an IBM Z hardware upgrade?
IBM Systems magazine, IBM Z - May/June 2020 - Beyond the Box: IBMer David Hilliard on his role as a locomotive engineer for the Catskill Mountain Railroad
IBM Systems magazine, IBM Z - May/June 2020 - Cover3
IBM Systems magazine, IBM Z - May/June 2020 - Cover4
IBM Systems magazine, IBM Z - May/June 2020 - SD
IBM Systems magazine, IBM Z - May/June 2020 - CoverSD1
IBM Systems magazine, IBM Z - May/June 2020 - CoverSD2
IBM Systems magazine, IBM Z - May/June 2020 - SD1
IBM Systems magazine, IBM Z - May/June 2020 - SD2
IBM Systems magazine, IBM Z - May/June 2020 - SD3
IBM Systems magazine, IBM Z - May/June 2020 - SD4
IBM Systems magazine, IBM Z - May/June 2020 - CT1
IBM Systems magazine, IBM Z - May/June 2020 - CT2
IBM Systems magazine, IBM Z - May/June 2020 - SD5
IBM Systems magazine, IBM Z - May/June 2020 - SD6
IBM Systems magazine, IBM Z - May/June 2020 - SD7
IBM Systems magazine, IBM Z - May/June 2020 - SD8
IBM Systems magazine, IBM Z - May/June 2020 - SD9
IBM Systems magazine, IBM Z - May/June 2020 - SD10
IBM Systems magazine, IBM Z - May/June 2020 - SD11
IBM Systems magazine, IBM Z - May/June 2020 - SD12
IBM Systems magazine, IBM Z - May/June 2020 - SD13
IBM Systems magazine, IBM Z - May/June 2020 - SD14
IBM Systems magazine, IBM Z - May/June 2020 - SD15
IBM Systems magazine, IBM Z - May/June 2020 - SD16
IBM Systems magazine, IBM Z - May/June 2020 - SD17
IBM Systems magazine, IBM Z - May/June 2020 - SD18
IBM Systems magazine, IBM Z - May/June 2020 - SD19
IBM Systems magazine, IBM Z - May/June 2020 - SD20
IBM Systems magazine, IBM Z - May/June 2020 - SD21
IBM Systems magazine, IBM Z - May/June 2020 - SD22
IBM Systems magazine, IBM Z - May/June 2020 - SD23
IBM Systems magazine, IBM Z - May/June 2020 - SD24
IBM Systems magazine, IBM Z - May/June 2020 - SD25
IBM Systems magazine, IBM Z - May/June 2020 - SD26
IBM Systems magazine, IBM Z - May/June 2020 - SD27
IBM Systems magazine, IBM Z - May/June 2020 - SD28
IBM Systems magazine, IBM Z - May/June 2020 - SD29
IBM Systems magazine, IBM Z - May/June 2020 - SD30
IBM Systems magazine, IBM Z - May/June 2020 - SD31
IBM Systems magazine, IBM Z - May/June 2020 - SD32
IBM Systems magazine, IBM Z - May/June 2020 - SD33
IBM Systems magazine, IBM Z - May/June 2020 - SD34
IBM Systems magazine, IBM Z - May/June 2020 - SD35
IBM Systems magazine, IBM Z - May/June 2020 - SD36
IBM Systems magazine, IBM Z - May/June 2020 - SD39
IBM Systems magazine, IBM Z - May/June 2020 - SD40
IBM Systems magazine, IBM Z - May/June 2020 - SD41
IBM Systems magazine, IBM Z - May/June 2020 - SD42
IBM Systems magazine, IBM Z - May/June 2020 - SD43
IBM Systems magazine, IBM Z - May/June 2020 - SD44
IBM Systems magazine, IBM Z - May/June 2020 - SD45
IBM Systems magazine, IBM Z - May/June 2020 - SD46
IBM Systems magazine, IBM Z - May/June 2020 - SD47
IBM Systems magazine, IBM Z - May/June 2020 - SD48
IBM Systems magazine, IBM Z - May/June 2020 - SD49
IBM Systems magazine, IBM Z - May/June 2020 - SD50
IBM Systems magazine, IBM Z - May/June 2020 - SD51
IBM Systems magazine, IBM Z - May/June 2020 - SD52
IBM Systems magazine, IBM Z - May/June 2020 - SD53
IBM Systems magazine, IBM Z - May/June 2020 - SD54
IBM Systems magazine, IBM Z - May/June 2020 - SD55
IBM Systems magazine, IBM Z - May/June 2020 - SD56
IBM Systems magazine, IBM Z - May/June 2020 - CoverSD3
IBM Systems magazine, IBM Z - May/June 2020 - CoverSD4
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