EMC Isilon Interview Questions And Answer

If you are applying for Isilon administrator jobs, then this post is going to be helpful to you. This post has the most common Dell EMC Isilon interview questions and answers.

Explore Brocade Switch Interview Questions.

It’s very hard to find interview questions for Isilon, that covers all topics of Isilon. Hence, I have gathered various probable question from various topics on Isilon.

These questions are most common and favourite topics of an interviwer. So, let jump int the questions.

Basic EMC Isilon Interview Questions

First, we will cover the most basic EMC Isilon interview question and then in later section we will focus on complex question.

What is OneFs In EMC Isilon?

OneFs stands for One File system. It is also the name of the Isilon cluster operating system. OneFs stats that Isilon uses a single filesystem, /ifs for the entire cluster.

Isilon Administrator can create sub-directories under /ifs and export them to CIFS shares and NFS exports.

What are the types of Isilon Nodes and their purposes?

  • Gen-6 Hardware F800 and F810 which are full flash SSD storage.
  • Gen-6 Hardware H-Series for performance-optimized.
  • For archiving purpose Gen-6 A series.
  • S-Series for IO-intensive application.
  • X-Series for high throughput intensive application.
  • NL-Series for higher capacity and low-level performance.
  • HD series for the maximum capacity.
  • A series performance accelerator which is independent of scaling but increase performance.
  • A series backup accelerator for faster backup and restore solution for tape over FC protocol.

Explain the architecture of EMC Isilon?

EMC Isilon serves data from a single and distributed file system over multiple nodes. An Isilon cluster consists of multiple nodes. Each node has its own resources such as CPU, RAM, NVRAM, Disk, network ports.

When you add a node to the cluster, it adds the nodes’ resources to the cluster and increases not only capacity but also global cache and overall performance of a cluster.

Each node contains a minimum of two ethernet ports which connects to LAN switches for client connection.

Similarly, each node has two redundant InfiniBand adapter which connects to InfiniBand switches for internal communication.

What is RAIN In Isilon?

RAIN stands for Redundant Array Of Independent Nodes. Isilon cluster follows RAIN concept instead of RAID and the OneFs distributes these data chunks to different nodes.

How to check the overall health status of Isilon nodes?

isi status

How to check a disk failure in EMC Isilon Cluster?

isi_for_array -s “isi devices drive list | grep -i REPLACE”

Minimum and a maximum node is needed to build the Isilon Cluster?

Isilon cluster can have minimum of 3 nodes and maximum of 144 nodes.

What Is Stripe units In EMC Isilon?

When Isilon receives a write operation, the OneFS splits the file into 8KB of blocks and then combines the blocks to a stripe unit.

The size of a stripe unit is 128KB, which means 16 number of 8KB blocks makes a stripe unit. Isilon distributes these strip units in different nodes of the cluster.

What is virtual Hot Spare (VHS) in EMC Isilon?

A virtual Hot Spare or VHS is a reserved space in Isilon. Whenever a disk failure happens, the data movement happens from the failed disk to the VHS.

What are the various authentication providers in Isilon?

  • Active Directory
  • LDAP
  • NIS
  • Local

How to collect support logs or diagnostics logs for Isilon?

isi diagnostics gather startBegins the collection, and uploads all recent cluster log information.
isi diagnostics gather stopStops the collection of cluster information.
isi diagnostics gather statusProvides the cluster status.
isi diagnostics gather viewView the information.
isi diagnostics netlogger startStarts the netlogger process
isi diagnostics netlogger stopStops the netlogger process.
isi diagnostics netlogger statusProvides the netlogger status.
isi diagnostics netlogger viewView the netlogger capture files.

If you are using an older version of OneFs then use isi_gather_info.

How To create NFS Export In Isilon?

Step 1. Create a directory under /ifs path.

Isilon-01# mkdir /ifs/prod
Isilon-01# mkdir /ifs/prod/data

Step 2. Create NFS export In Isilon

Isilon-01# isi nfs exports create –paths=/ifs/prod/data –map-root=root –clients=, –security-flavors=unix –map-lookup-uid=Yes

To check the NFS export details use below command.

Isilon-01# isi nfs exports list | grep /ifs/prod/data
6 System /ifs/prod/data –

Step 3. To Check the details of NFS export execute below command.

Isilon-01# isi nfs exports view 6

How To create CIFS share In EMC Isilon?

Step 1. Create a directory under /ifs path.

Isilon-01# mkdir /ifs/prod
Isilon-01# mkdir /ifs/prod/data

Step 2. Create CIFS Share in Isilon.

isi smb shares create multi_test –path=/ifs/prod/data

Step 3. Provide Share Level Permission. Change the default read-only permission to full.

isi smb shares permission modify –share=multi_test –wellknown=Everyone –permission=full –permission-type=allow

Step 4. Provide security level DACL permission.

chmod +a# 0 user domain\user allow dir_gen_read,dir_gen_execute,object_inherit,container_inherit /ifs/prod/data

What are the different types of quota in Isilon?

Isilon support three type quota directory, users, and groups.

What are the types quota threshold in Isilon?

There are three types of quota threshold Hard, Soft, Advisory. Hard quota restricts usage to a certain size. Once the hard quota is reached the user will not be able to write anything.

Soft quota still allows write for grace period but once the grace period is over, the additional writes will fail. In the case of an advisory threshold, a simple notification will be sent to the users.

How to create a quota in Isilon?

Below commands create a directory type quota on Isilon path with a hard threshold of 200M and an advisory threshold of 100MB. The enforced option ensures that the quota is applicable and new writes fail once the quota threshold reaches the limit.

If you do not specify this option then quota is just informative and the user can write, more than the hard threshold quota.

isi quota quotas create –path=/ifs/data/quota_test_2 –type=directory –hard-threshold=200M –advisory-threshold=100M –enforced=true

EMC Isilon Interview Questions On SyncIQ

In this section, we will discuss the Isilon questions on replication and migrations.

What is SyncIQ?

SyncIQ is the disaster recovery tool for EMC Isilon. SyncIQ policies replicate data from Primary Isilon to a Secondary Isilon Cluster. If primary Isilon fails then all clients can access the data from the secondary Isilon cluster.

How many types of SyncIQ policies are there and what is the difference between them?

There are two types of SyncIQ policies sync and copy. Sync policies maintain an exact copy of data between source and destination, whereas in copy policy data exists in secondary even if it does not exists in source.

Sync policies support failback and failover, but copy policies do not support them.

How many maximum SyncIQ job policies can run at a time?


How to configure SyncIQ replication in Isilon?

Step 1. Activate SyncIQ license in both source and secondary Isilon Cluster.
Step 2. Create a SyncIQ replication policy of type sync in primary Isilon cluster.

The following command creates a policy that replicates the directory /ifs/data/source on the source cluster to /ifs/data/target on target cluster every week.

The command also creates archival snapshots on the target cluster:

isi sync policies create mypolicy sync /ifs/data/source /ifs/data/target –schedule “Every Sunday at 12:00 AM” –target-snapshot-archive on –target-snapshot-expiration 1Y –target-snapshot-pattern “%{PolicyName}-%{SrcCluster}-%Y-%m-%d

Step 3. Test the sync policy in the primary cluster.

isi sync jobs start weeklySync –test

Step 4. Start the replication policy in the primary cluster.

isi sync jobs start weeklySync

Step 5. Monitor the replication policy.

isi sync jobs view weeklySync

How to do SyncIQ failover and failback when primary Isilon cluster is still online?

Step 1. Modify the policy to manual replication mode in primary Isilon.

isi sync policies modify weeklySync –schedule “”

Step 2. Use the below command to allow writes in the secondary cluster.

isi sync recovery allow-write weeklySync

Step 3. DNS change or instruct clients to use the secondary cluster.
Step 4. Revert the sync to start the replication again.

Use below command in the secondary cluster to start repliction again.

isi sync recovery allow-write weeklySync –revert

How to do SyncIQ failover and failback when primary Isilon cluster is down?

Step 1. Execute below command to allow writes in secondary cluster.

isi sync recovery allow-write weeklySync

Step 2. DNS change or instruct clients to use the secondary cluster.
Step 3. When the primary cluster is up perform failback.

Create a mirror policy in the secondary cluster by executing below command in the primary cluster.

isi sync recovery allow-write weeklySync –revert

Above command will replicate modified data from the secondary cluster to the primary cluster.

Stop the client accessing the secondary cluster. This step ensures that there is no new data during failback.

On Secondary cluster start the mirror replication policy. Mirror replication policy will start copying the data from secondary to the primary cluster.

isi sync jobs start weeklySync_mirror

After the sync is completed, on primary cluster execute below command to allow writes.

isi sync recovery allow-write weeklySync_mirror

Finally, complete the failback process by starting the replication from primary to secondary. Execute the below command in secondary.

isi sync recovery resync-prep weeklySync_mirror

Which SyncIQ policy type support failover and failback?

Sync policy type supports failover and failback operation. A sync policy with type copy does not support failback and failover operation.

How to Migrate Data From NetApp To Isilon?

To migrate data from NetApp to Isilon, you can use the inbuild isi_vol_copy utility. you can also use host-based migration solutions like RoboCopy and Rsync.

How to set up three-way NDMP in Isilon Cluster?

Step 1. Enable NDMP services in Isilon.

isi ndmp settings global modify –service=true

Step 2. Set the respective DMA type according to target backup devices.

isi ndmp settings global modify –dma=emc

Step 3. Create an NDMP user.

isi ndmp users create –name=NDMPuser –password=1234

EMC Isilon Storage Pool Interview Questions

In this section, we will discuss Isilon Interview questions related to storage pools and file pool policies.

What is Isilon Storage Pool?

An Isilon storage pool is the grouping of Isilon nodes. When new nodes are added, OneFs adds the nodes to the node pools. You can also create tiers by grouping different types of nodes.

You can move files to different tiers by creating file pool policy, but you must activate SmartPool license for that.

What is file pool policies in Isilon?

A file policy consists of certain conditions and it is responsible for distributing files between various storage tiers. You need a SmartPool license to create file pool policies.

What is L3 Cache in Isilon?

An L3 cache is a group of SSD disk in an Isilon node which acts as a cache and increases the cluster performance.

L3 cache is non-volatile in nature and global in scope, which means increasing L3 cache increase entire clusters L3 cache.

Can you create a node pool manually?

Yes we can create node pool manually in Isilon using below commands

isi storagepool nodepools create nodepool 1 –lnns 1,2,5

(1,2,5 are node numbers.)

How to configure Isilon storage tiers?

You can create Isilon storage tiers in two steps.

Step 1. Create storage tiers.
Step 2. Add node pools to the storage tiers.

isi storage pool tiers create archive_tier –children nodepool1 –children nodepool2

What is the difference between AutoBalance and AutoBalanceLin jobs?

AutoBalance balances the free space in the Isilon cluster and it is efficient when only HDD disks exist. On the other hand, AutobalanceLin is best when file system metadata exists in SSD disks.

Which jobs is responsible for InsightIQ data?


What is the purpose of FlexProtect and FlexProtectLin job in Isilon?

Whenever a hardware failure happens FlexProtect scans the file system and ensures all file systems are protected. FlexProtectLin also does the same but only if SSD disk is there in the cluster.

Networking Related EMC Isilon Interview Questions

In this section, I will tell you some network related EMC Isilon interview questions. If you are applying for L3 position, then network related questions are most common in an interview.

Can you explain the network architecture of Isilon?

Isilon Network has two parts Internal and external.

The internal network connects all nodes via InfiniBand switches. Communication between all nodes happens through these InfiniBand switches.

The external network connects all nodes to ethernet ports of LAN switches. Clients connect to the cluster via an external network using a communication protocol such as NFS, CIFS, HDFS, FTP and HTTP.

Various components of an external network are GroupNets, subnets, IP address pools.

GroupNets are the top layer in Isilon network architecture and it consists of one or more multiple subnets. You can have multiple GroupNets but a single subnet cannot be a part of multiple GroupNets.

A subnet is created under GroupNets and it divides the network into logical IP networks. A subnet can contain one or more IP address pool.

The IP address pool is nothing but a range of IP address which dynamically assigned to the ports.

In a subnet, we can configure, gateway, VLAN, MTU and SmartConnect Service IP.

What Is SmartConnect?

SmartConnect is a feature in Isilon which is responsible for load balancing and distributing all incoming client connection to various nodes. There are two smart connect modules basic and advanced.

In basic, only round-robin load balancing is available, whereas in advanced load balancing you can configure load balancing with nodes CPU utilization, Number of IOPS and number of the client connection.

How to Configure SmartConnect DNS zone In Isilon?

Step 1. Specify a SmartConnect service IP in subnet.
Step 2. Configure a DNS zone name with FQDN
Step 3. Create a DNS delegation entry pointing to service IP.

You can watch the below video that explains the configuration of SmartConnect DNS in Isilon. For more such videos subscribe to the channel.


Above are the most common EMC Isilon interview questions. If you feel anything is missed out, feel free to comment and I will try to cover the topics.

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