InterSystems IRIS

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** Revised Feb-12, 2018

While this article is about InterSystems IRIS, it also applies to Caché, Ensemble, and HealthShare distributions.

Introduction

Memory is managed in pages.  The default page size is 4KB on Linux systems.  Red Hat Enterprise Linux 6, SUSE Linux Enterprise Server 11, and Oracle Linux 6 introduced a method to provide an increased page size in 2MB or 1GB sizes depending on system configuration know as HugePages.

At first HugePages required to be assigned at boot time, and if not managed or calculated appropriately could result in wasted resources.  As a result various Linux distributions introduced Transparent HugePages with the 2.6.38 kernel as enabled by default.  This was meant as a means to automate creating, managing, and using HugePages.  Prior kernel versions may have this feature as well however may not be marked as [always] and potentially set to [madvise].  

Transparent Huge Pages (THP) is a Linux memory management system that reduces the overhead of Translation Lookaside Buffer (TLB) lookups on machines with large amounts of memory by using larger memory pages.  However in current Linux releases THP can only map individual process heap and stack space.

Last comment 22 February 2017
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One of the great availability and scaling features of Caché is Enterprise Cache Protocol (ECP). With consideration during application development distributed processing using ECP allows a scale out architecture for Caché applications. Application processing can scale to very high rates from a single application server to the processing power of up to 255 application servers with no application changes.

ECP was used widely for many years in TrakCare deployments I was involved in. A decade ago a 'big' x86 server from one of the major vendors might only have a total of eight cores. For larger deployments ECP was a way to scale out processing on commodity servers rather than a single large and expensive big iron enterprise server. Even the high core count enterprise servers had limits so ECP was also used to scale deployments on them as well

Last comment 8 December 2016
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This post provides guidelines for configuration, system sizing and capacity planning when deploying Caché 2015 and later on a VMware ESXi 5.5 and later environment.

I jump right in with recommendations assuming you already have an understanding of VMware vSphere virtualization platform. The recommendations in this guide are not specific to any particular hardware or site specific implementation, and are not intended as a fully comprehensive guide to planning and configuring a vSphere deployment -- rather this is a check list of best practice configuration choices you can make. I expect that the recommendations will be evaluated for a specific site by your expert VMware implementation team.


A list of other posts in the InterSystems Data Platforms and performance series is here.

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In this post I would like to talk about the syslog table.  I will cover what it is, how you look at it, what the entries really are, and why it may be important to you.  The syslog table can contain important diagnostic information.  If your system is having any problems, it is important to understand how to look at this table and what information is contained there.

Last comment 9 November 2016
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