Diagnosis and Performance Monitoring - Deploying and Managing a Cloud Infrastructure - page 154

by revolutions per minute, and the actuator arm lateral movement speed, which brings the
head over the correct track.
The file system also plays a major role in the performance of a storage system. It is
important that the file system be configured specifically, tailor-made if you will, to your
purpose, which is cloud and distributed computing. Common file systems used in this area
are FFS and NFS. Most operating system users, especially Windows users, take the file
system for granted because it is largely invisible to them, so it takes a back seat when enthu-
siast modders and gamers tweak their computer's performance. But for a service entity that
deals almost exclusively in data, the file system is probably one of the most important fac-
tors in the service infrastructure. This is where most of the performance in the system can
be attained or lost because cloud applications are mostly data related and data dependent.
From the file system, you can control I/O operations and metadata operations, which helps
to speed up various processes through proper tuning.
We also discussed various methods that help increase disk and memory performance,
such as I/O tuning and disk swapping or paging.
Chapter Essentials
Performance Concepts Although a multitenant cloud system is a diverse system with
many capabilities, all of them are tied to data, which is in turn stored in disks. When talk-
ing about performance concepts, we often mean the criteria for which we judge a specific
system or its constituents. In the case of cloud computing, it is usually the database and the
storage system.
File system performance, I/O operations rate of processing, read and write operation
speeds, and metadata performance are a few of these performance concepts that an IT
professional, not just a cloud expert, should be familiar with.
Disk Performance The disk is kind of like the bread and butter of the enterprise. Since disk
performance has not really improved by leaps and bounds in the last decade, we are left with
finding the right drives from the right manufacturers by taking advantage of every microsec-
ond of performance we can. We are looking for great performance in access time and data
transfer rate, which are characterized by the internal mechanical parts of the drive.
Disk Tuning This is the optimization of a disk's performance in conjunction with other
hardware and the software platform that is used to manage it. Obviously you cannot make
a disk perform any better or faster than it's capable of, unlike processors, which can be
overclocked. You can only make them perform at their best through proper configuration
of settings and tuning the file system itself to work in the best way possible. You must take
into account the actual performance of the disks being used, which is reduced to really just
limiting I/O requests to the disks and doing batch file access and transfers because the disks
are pretty much the biggest bottleneck in any system.
Swap Disk Space The swap disk space is essentially a specially assigned portion of the
disk that is being used as a place to temporarily store data from the main memory, known