Which two statements are true about Flex ASM in a Flex Cluster?
A.
Oracle databases from releases older than 12c cannot use Flex ASM.
B.
ASFS may only be configured on a hub node running an ASM instance.
C.
Instances of ASM-based databases on hosts that have no ASM instance running, require Flex ASM.
D.
Flex ASM requires that I/Os requests be sent through an ASM Proxy Instance, regardless of database and ASM instance placement in a cluster.
E.
Hub nodes with connections from multiple leaf nodes must run an ASM instance.
A and E are corrects
B E
The Oracle Flex ASM can be implemented in two ways:
Pure 12c Flex ASM (Same Version)
Both Grid Infrasctructure (GI) and Database running on Oracle 12c
Pre Oracle 12c Mixed (Different Versions)
As normal ASM instance will run on each node with Flex configuration to support pre 12c database. The compatibility parameter of ASM disk group is used to manage the compatibility of between and among database instances. Advantage of this approach is that if an Oracle 12c database instance loses connectivity with an ASM instance, then the database connections will failover to another ASM instance on a different server. This failover is achieved by setting the cardinality to all.
you’re right
thank you so much
The question “A” is right!
Oracle Grid Infrastructure 12c Release 1 In Practice – (Robert Bialek/ Trivadis GmbH/Munich, DE)
“… If you use an older database release with Flex ASM you need to change the ASM cardinality to ALL (or set it to the current amount of nodes). After increasing the cardinality the ASM instance(s) will be started automatically on the appropriate node(s) in order to achieve the desired amount of instances.”
An Insight into Oracle Flex ASM and Its Benefits
http://www.oracle.com/technetwork/articles/database/flexasm-flexcluster-benefits-odb12c-2177371.html?printOnly=1
“Pre Oracle 12c Mixed (Different Versions)
As normal ASM instance will run on each node with Flex configuration to support pre 12c database. The compatibility parameter of ASM disk group is used to manage the compatibility of between and among database instances. Advantage of this approach is that if an Oracle 12c database instance loses connectivity with an ASM instance, then the database connections will failover to another ASM instance on a different server. This failover is achieved by setting the cardinality to all.”
The question “B” is wrong!
“ADVM Proxy
The ADVM Proxy is a special Oracle instance.
• It enables ADVM to connect to Flex ASM.
• It is required to run on the same node as ADVM and ACFS.
• It can be shut down when ACFS is not running.
The ADVM proxy is a special Oracle instance. Its sole purpose is to enable ASM Dynamic Volume Manager (ADVM), and through it ASM Cluster File System (ACFS), to connect to Flex ASM.
In release 12.1, ACFS, ADVM, and the ADVM proxy must reside on the same node. So by default, the ADVM proxy is configured to run on every node in a standard cluster or every Hub Node in a Flex Cluster. However, when Flex ASM is configured by using cardinality = ALL), the ADVM proxy (ora.proxy_advm) is not required because the ASM instances are up and running on all nodes to handle ADVM volumes and ACFS file systems. Administrators can shut down the ADVM proxy if ACFS is not running on the node.
The ADVM proxy instance has its ORACLE SID set to +APX.”
And, i think that “C” is right…
I can run a database like a client of a remote ASM instance
http://www.oracle.com/technetwork/articles/database/flexasm-flexcluster-benefits-odb12c-2177371.html?printOnly=1
“D” is wrong too!
The Oracle ACFS driver establishes communication with the Oracle ASM instance to receive Oracle ASM status information including Oracle ASM instance and disk group state transitions. However, I/O does not go through Oracle ASM nor through the Oracle ASM proxy, but rather goes directly to the underlying Oracle ASM storage.
AND “E” is wrong!
Because the leaf node doesn’t necessarily need to access a ASM or a Database, they can be only a application node
Ops! “…cannot…”
This is: “A” is wrong!
Think in two groups of servers, the first one with all older versions instances, and every one with an ASM Instance (12c)…
And, think in another group of servers in the same cluster, and in this servers, my RDBMS is 12c and they can use “Flex ASM”, acessing the ASM Instance in the first group of servers.
But, in this case has only “E” like the second (best) choice!
What is the correct final answer?
Is it C and E or A and C or A and E
“Expert Oracle RAC 12c
In the Oracle 12c Flex Cluster configuration, a Leaf node connects to the cluster through a Hub node. The failure of the Hub Node or the failure of network between the Hub node and the Leaf nodes results in the node eviction of the associated Leaf nodes.”
So I think that “C” and”E”
B – wrong asm proxy
D – wrong
C- right
which leaves A or E.
For A pre 12c databases need an asm instance on every hub node, but this seems to be a flex ASM configuration
For E I can’t find anything that says a hub node with connections from multiple leaf nodes needs to run an asm instance, and doing so would seem to defeat one of the advantages of minimizing asm resources. If you had a 4 node hub with 8 leaf nodes then presumably you would load balance them with 2 leaf nodes to each hub, which would mean each hub needed to run an asm instance.
Correct B, D
I will take a moment to explain just because there are many different opinions here…
A – wrong Flex ASM can run in Oracle databases from 12c and above…
B – correct , this answer has an typo error it means ACFS, and in this case ACFS only can run on ASM instance running on the same host… Source : D81242GC10 Oracle Database 12c: ASM Administration 3-3
C – correct, Source: D81242GC10 Oracle Database 12c: ASM Administration 3-17
D – wrong,
E – wrong, it is not a required… I mean by definition the hub nodes have to had access to ASM instance, it could be local or by network… it does not matter how many leaf node they have… the requirement is that they have to be connected to an ASM instance…
Think Is A,C.
B is wrong because ACFS could run on Hub nodes that dont have ASM instance, that’s why It’s Flex ASM.
The same happend to D. A hub node can have leaf nodes without having an ASM instance.
I made some test and 11g Database cannot use FLEX ASM.
Agree, A and C
B is incorrect -> ASM instance is NOT required on HUB node to have ACFS
https://docs.oracle.com/database/121/OSTMG/GUID-545C311D-24C6-421A-ACBE-CA29E1FDA0A6.htm
Oracle ACFS access through the Oracle ASM proxy instance
An Oracle ASM proxy instance is an Oracle instance running on a Hub node with a direct Oracle ASM client. Oracle Automatic Storage Management Cluster File System (Oracle ACFS) and Oracle ASM Dynamic Volume Manager (Oracle ADVM) are supported with an Oracle ASM proxy instance. This configuration is shown in Figure 3-2.
The INSTANCE_TYPE initialization parameter is set to ASMPROXY for Oracle ASM proxy instances.
or better take a look at the “all saying” image:
https://docs.oracle.com/database/121/OSTMG/img_text/GUID-52D3B67C-9969-4CE3-80C8-A9DEC21EAEBE-print.htm
ACFS active on HUB node (as it cannot be active on LEAF) where is NO ASM instance. There is PROXY ASM instance which allows runnig the ACFS.
C is correct – no doubts here… if there was no FLEX ASM then how ASM-based DB would connect to storage? using ASM PROXY instance which is part of FLEX ASM tech.
A is incorrect – FLEX ASM is just new technology with many implemented solutions. One of them is using ASM PROXY instance on HUB node to connect to ASM hosted on another HUB node, but it is only PART of the FLEX ASM. Pre 12c DBs can use FLEX ASM as technology, however they cannot use it’s part called PROXY ASM.
http://www.oracle.com/technetwork/articles/database/flexasm-flexcluster-benefits-odb12c-2177371.html
E is incorrect – I bet because there is no single word that existence of LEAF nodes require ASM instance running on HUB node.
D would be correct if we talk about ACFS and ADVM what is the only reason for ASM PROXY instance and then I/O requests (for ACFS and ADVM only) fly thru PROXY no matter if there is “real” ASM instance on the node or not:
https://docs.oracle.com/database/121/OSTMG/img/GUID-52D3B67C-9969-4CE3-80C8-A9DEC21EAEBE-default.png