Jason Arneil Solutions Architect

Slide 1

Jason ArneilSolutions ArchitectWhats New with 12c ASM Oracle EMEA Database Partner of the Year

Oracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

In this presentation Im going to take a look at the new features of ASM available with the 12c release.

How many of you use ASM for your databases?

1AgendaConsolidation

Oracle EMEA Database Partner of the Year


So what am I going to talk about today

RECAP

NEW FEATURES

DEMO2

jarneil.wordpress.com@jarneilOracle EMEA Database Partner of the Year


My name is Jason Arneil

Been in IT for around 15 years

SA/DBA

Written quite a few blog articles

also on twitter

now an oracle AceCustomers


Work in the Engineered Systems Team at e-dba

Team is 100% focused on the e-dba Exadata customers

e-dba are on Oracle platinum partner

We have our own Exadata x3-2 and exalytics boxes available for POC

4

ASMOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

When Automatic Storage Management (ASM) was introduced in 10gR1

ASM was designed as a purpose-built host based volume management and file system that is integrated with the Oracle database.

It is built on stripping and mirroring methodology (SAME)

ASM is built on the Oracle instance architecture5ASM A recap


Just like the database has a storage hierarchy

going from the data block upto the tablespace

There is a similar hierarchy in ASM

From the DBAs view, ASM exposes Disk Groups you can think of the DISKGROUP as like a filesystem

and it is in a diskgroup that tablespaces are created

These Disk Groups consists of ASM disks and files that are stripped across all the disks in a Disk Group.

Every ASM disk is divided into allocation units (AU).

An AU is the fundamental unit of allocation within a disk group.

A file extent consists of one or more AU. An ASM file consists of one or more file extents.

6ASM Protection

Oracle EMEA Database Partner of the Year


3 LEVELS of ASM PROTECTION for your data

EXTERNAL lets the storage array take care of it

NORMAL write 2 copies of your extents

HIGH write 3 copies of your extents

7Extents & RedundancyOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

Every ASM disk is divided into allocation units (AU).

An AU is the fundamental unit of allocation within a disk group.

A file extent consists of one or more AU. An ASM file consists of one or more file extents.

8AgendaWhats New?Oracle EMEA Database Partner of the Year


9Disk ManagementPhysical Metadata ReplicationImproved AvailabilityOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

Physical Metadata Replication

Oracle ASM now replicates physically addressed metadata

like disk header, free space blocks and allocation table

This is tracked with a diskgroup attribute PHYS_META_REPLICATED

turned on when ASM compatibility of the diskgroup is advanced to 12.1

This ensures ASM is more resilient to bad disk sectors and external corruptions10Disk ManagementConcurrent RebalanceImproved AvailabilityOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

In previous versions, an ASM instance could only perform one rebalance operation at a time on the same instance.

If two disk group rebalance requests (for two different disk groups) were issued within the same ASM instance, then the second rebalance operation would be queued up behind the first request

With Oracle Database 12c, a single ASM instance can now perform multiple rebalance operations concurrently11Disk ManagementFile Priority RebalanceImproved Availability Oracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

Upon a rebalance due to a failed disk drive ASM will now restore the redundancy of the data based on the criticality of the files.

i.e. control files and redo logs will have their redundancy restored first.12Disk ManagementDisk ScrubbingImproved Availability Oracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

Upon a rebalance due to a failed disk drive ASM will now restore the redundancy of the data based on the criticality of the files.

i.e. control files and redo logs will have their redundancy restored first.

Can set the CONTENT.CHECK attribute on a diskgroup to ensure a rebalance will perform this logical content checking13Disk ManagementFast Disk Resync CheckpointsImproved availability Oracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

When a disk drive suffers a transient failure temporarily becoming unavailable a rebalance does not have to occur immeidately

Instead the changes that would have been written to this unavailable disk are tracked

and when the disk becomes avaialble again those changes can be synced to the disk

While this was available in 11g, if that sync got interrupted it would have to restart from the beginning

Now in 12c there are checkpoints so and interruption will not mean having to repeat lots of changes already done

Also possibility to set a power limit for the resync operation

14Disk ManagementFailure Group Repair TimerImproved availability Oracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

In addition to a repair timer being set for an individual disk

Can now be set for an entire failure group by default this is 24h

the idea being that a failure of entire failure group is likely to be transient therefore dont do a big rebalance

however with normal redundancy you have a bigger exposure to data loss if another disk fails

15I/O PerformanceEven ReadImproved PerformanceOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

Default behaviour of ASM has been to only read primary extents

Even Read ensures the extent that resides on the least loaded device will be read

Even Read is enabled by default

This should improve the performance of I/O bound systems.

16ScalabilityIncreased Number of DiskgroupsImproved ScalabilityOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

number of diskgroups supported has gone from 63 to 51117EstimatingExplain WorkImproved ManageabilityOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

18Password FilesPassword Files in ASMImproved ManageabilityOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

Previously almost all database and ASM related files could be stored in ASM.

A key exception was the password file

both the ASM and database password files could not be stored in ASM

For 12c the default location of the password file is ASM

Note that the compatible.asm disk group attribute must be set to 12.119Flex ASM


So currently

Tight 1:1 binding of ASM to cluster host

Loss of an ASM instance means loss of all databases on that server

In a cloud environment (PaaS) this less than desirable

20Flex ASMCurrent scenarioASM Cluster Pool of StorageNode2

Disk Group BDisk Group ANode3Node5Node4

Shared Disk Groups

Wide File Striping

One to One Mapping of ASM Instances to Servers

Node1

ASM InstanceDatabase InstanceASM Disk


If an ASM instance on a node crashes

ALL instances on that node will crash

This is not good, particularly in a consolidated environment where many, many instances could be impacted21Flex ASM


Now with 12c You dont need an ASM instance running on each and every node!

DB Instances can use an ASM instance running on another node

By default you have 3 ASM instances for a cluster this is controlled via the ASM cardinality

If an node running one of the ASM instances fails an ASM instance will be restarted on another node

Instances running on a node wont crash if ASM on that node crashes.22Flex ASMWith Flex ASMASM Cluster Pool of StorageDisk Group BDisk Group AShared Disk Groups

Wide File Striping

Databases share ASM instances

ASM InstanceDatabase InstanceASM Disk

Node5Node4

Node3

Node2

Node1

Node5

Node5 runs as ASM Client to Node4 Node1 runs as ASM Client to Node2 Node1 runs as ASM Client to Node4 Node2 runs as ASM Client to Node3 Oracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

Flex ASM


12c provides for a dedicated network for ASM traffic

Remember its metadata (files extent maps etc) etc NOT all IO traffic

DATABASES do NOT perform their I/O via the ASM instance, once they have the metadata they talk to the storage direct.

Can use the Clusterware private interconnect

24Flex ASM3


25Flex ASMClassic ModeMixed Mode12c ModeOracle Partner of the year 2010 & 2012 +44 (0) 844 811 [email protected] RedStack Technology CompanyOracle EMEA Database Partner of the Year

26Q & A


Documents

Jason Arneil Solutions Architect