HugePages for Oracle Database in Azure Cloud

Written by Jose Rodriguez | Aug 22, 2018 4:00:00 AM

So, what's up?

In case you don't know, my co-worker Gleb Otochkin has written a couple of blog entries about HugePages' support in different cloud providers here and here. Given that I am preparing a presentation about HugePages, I reached out to him and asked if he has something similar in the oven for Azure, but he hasn't. So I put my researcher hat on and initiated a simple test: create an Oracle database in an Azure instance and test if it would accept the HugePages configuration. Short story even shorter: yes, it does.

The start

It all starts with a brand new Azure account. Microsoft has been so kind as to offer an initial "Free Trial" account than includes 200€ in credits that last only 30 days, meaning that if by the end of the 30 days period you haven't used them, you lose them. These credits are good to use in the Pay-As-You-Go subscription model to create a simple VM running the latest Azure available Red Hat Linux image which happens to be RHEL 7.2. Unfortunately, this does not include Oracle Linux support, so we cannot use the brand new Red Hat compatible Oracle preinstallation RPM. Anyway, after some struggle in the initial account creation, I was able to quickly deploy a "Standard B2s (2 vcpus, 4 GB memory)" VM with the mentioned RHEL 7.2.

Creating the database and testing HugePages

Being this a basic RHEL image, it did not include any of the Oracle required OS configuration to deploy Oracle. Given that I don't have an Oracle Linux license, I can't use the brand new 18c Oracle RPM or even the basic Oracle preintallation RPM. So, after manually configuring the OS, (I know there are Ansible workbooks for that), I chose to both install the binaries and to create a basic database with the Oracle Universal Installer for 12.2 Oracle database. Why 12.2 and not another version? To be honest, this was a quick and dirty experiment from the very beginning and this version was the first to appear in my search in Oracle Delivery. Using the response file template included in the binaries I ran the installer and after a few minutes got both the binaries installed and the database up and running. In case you, dear reader, are interested here it goes:

oracle.install.responseFileVersion=/oracle/install/rspfmt_dbinstall_response_schema_v12.2.0
 oracle.install.option=INSTALL_DB_AND_CONFIG
 UNIX_GROUP_NAME=oinstall
 INVENTORY_LOCATION=/apps/oracle/inv
 ORACLE_HOME=/apps/oracle/db_home1
 ORACLE_BASE=/apps/oracle
 oracle.install.db.InstallEdition=SE2
 oracle.install.db.OSDBA_GROUP=dba
 oracle.install.db.OSOPER_GROUP=dba
 oracle.install.db.OSBACKUPDBA_GROUP=dba
 oracle.install.db.OSDGDBA_GROUP=dba
 oracle.install.db.OSKMDBA_GROUP=dba
 oracle.install.db.OSRACDBA_GROUP=dba
 oracle.install.db.rac.configurationType=
 oracle.install.db.CLUSTER_NODES=
 oracle.install.db.isRACOneInstall=
 oracle.install.db.racOneServiceName=
 oracle.install.db.rac.serverpoolName=
 oracle.install.db.rac.serverpoolCardinality=
 oracle.install.db.config.starterdb.type=GENERAL_PURPOSE
 oracle.install.db.config.starterdb.globalDBName=ORCL
 oracle.install.db.config.starterdb.SID=ORCL
 oracle.install.db.ConfigureAsContainerDB=false
 oracle.install.db.config.PDBName=
 oracle.install.db.config.starterdb.characterSet=AL32UTF8
 oracle.install.db.config.starterdb.memoryOption=false
 oracle.install.db.config.starterdb.memoryLimit=2048
 oracle.install.db.config.starterdb.installExampleSchemas=false
 oracle.install.db.config.starterdb.password.ALL=***************
 oracle.install.db.config.starterdb.password.SYS=
 oracle.install.db.config.starterdb.password.SYSTEM=
 oracle.install.db.config.starterdb.password.DBSNMP=
 oracle.install.db.config.starterdb.password.PDBADMIN=***************
 oracle.install.db.config.starterdb.managementOption=DEFAULT
 oracle.install.db.config.starterdb.omsHost=
 oracle.install.db.config.starterdb.omsPort=
 oracle.install.db.config.starterdb.emAdminUser=
 oracle.install.db.config.starterdb.emAdminPassword=
 oracle.install.db.config.starterdb.enableRecovery=false
 oracle.install.db.config.starterdb.storageType=FILE_SYSTEM_STORAGE
 oracle.install.db.config.starterdb.fileSystemStorage.dataLocation=/apps/oracle/oradata
 oracle.install.db.config.starterdb.fileSystemStorage.recoveryLocation=/apps/oracle/oradata
 oracle.install.db.config.asm.diskGroup=
 oracle.install.db.config.asm.ASMSNMPPassword=
 MYORACLESUPPORT_USERNAME=
 MYORACLESUPPORT_PASSWORD=
 SECURITY_UPDATES_VIA_MYORACLESUPPORT=false
 DECLINE_SECURITY_UPDATES=TRUE
 PROXY_HOST=
 PROXY_PORT=
 PROXY_USER=
 PROXY_PWD=
 COLLECTOR_SUPPORTHUB_URL=

A little issue, of course

Even though everything went fine after fixing one or two parameters and installing a couple missing RPMs, when the database started, it failed to allocate the HugePages.

2018-08-20T12:31:53.072289+00:00
  Per process system memlock (soft) limit = 64K
 2018-08-20T12:31:53.072378+00:00
  Expected per process system memlock (soft) limit to lock
  SHARED GLOBAL AREA (SGA) into memory: 1540M
 2018-08-20T12:31:53.072469+00:00
  Available system pagesizes:
  4K, 2048K 
 2018-08-20T12:31:53.072659+00:00
  Supported system pagesize(s):
 2018-08-20T12:31:53.072719+00:00
  PAGESIZE AVAILABLE_PAGES EXPECTED_PAGES ALLOCATED_PAGES ERROR(s)
 2018-08-20T12:31:53.072857+00:00
  2048K 1056 770 0 ORA-27125
 2018-08-20T12:31:53.072922+00:00
  Reason for not supporting certain system pagesizes: 
 2018-08-20T12:31:53.072983+00:00
  4K - Large pagesizes only
 2018-08-20T12:31:53.073063+00:00
 RECOMMENDATION:
 2018-08-20T12:31:53.073103+00:00
  1. Increase per process memlock (soft) limit to at least 1540MB
  to lock 100% of SHARED GLOBAL AREA (SGA) pages into physical memory
 2018-08-20T12:31:53.073187+00:00

Yes, the database failed to allocate the required HugePages due to a memlock soft limit issue. For some reason I didn't explore, all the other soft and hard resource limits were applied successfully upon creating a new session for the 'oracle' user, but not this one. A quick reboot of the VM fixed this and the database came up like a charm. The alert log shows the proper expected information regarding reserved HugePages:

2018-08-20T12:43:18.163509+00:00
 Dump of system resources acquired for SHARED GLOBAL AREA (SGA)
 
 2018-08-20T12:43:18.163653+00:00
  Per process system memlock (soft) limit = 2048M
 2018-08-20T12:43:18.163821+00:00
  Expected per process system memlock (soft) limit to lock
  SHARED GLOBAL AREA (SGA) into memory: 1540M
 2018-08-20T12:43:18.163952+00:00
  Available system pagesizes:
  4K, 2048K
 2018-08-20T12:43:18.164143+00:00
  Supported system pagesize(s):
 2018-08-20T12:43:18.164220+00:00
  PAGESIZE AVAILABLE_PAGES EXPECTED_PAGES ALLOCATED_PAGES ERROR(s)
 2018-08-20T12:43:18.164382+00:00
  2048K 1056 770 770 NONE

And so does the OS meminfo:

[oracle@HPtesting ~]$ grep ^HugePages /proc/meminfo 
 HugePages_Total: 1056
 HugePages_Free: 287
 HugePages_Rsvd: 1
 HugePages_Surp: 0

So, as my spoiler stated at the very beginning of the post, yes, we can use HugePages on Azure Cloud Red Hat Linux 7.2 virtual machines. I hope you enjoyed this.

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