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NetApp Interview Questions

NetApp Interview Questions

Q. How to improve the Netapp storage performance?

There is no direct answer for this question but we shall do it in several way.

  • If volume/lun present in ATA/SATA harddisk aggregate, then the volume can be migrated to FC/SAS disk aggregate. Either you can use flash cache to improve performance.
  • For NFS/CIFS instead of accessing from single interface, multi mode vif can be configured to get better bandwidth and fault tolerance.
  • Always advised to keep aggr/vol utilization below 90%.
  • Avoid doing multiple volume backup in single point of time.
  • Aggr/volume/lun reallocation can be done to re–distribute the data to multiple disk for better striping performance.
  • Schedule scrubbing and De-duplication scanning after business hours.
  • Create multiple loops and connect different types of shelf’s to each loop
  • Avoid mixing up different speeds of disk and different types of disk in a same aggregate.
  • Always keep sufficient spare disk to replace in case of disk failure. Because reconstruction time will take more time and cause negative performance.
  • Keep the advised version of firmware/software which is recommended by Netapp.

 

Q. Unable to map lun to solaris server, but solaris server side no issue. How to resolve the issue?

FROM STORAGE SIDE:

   Verify iscsi/fcp license is added in storage

   Verify iscsi/fcp session is logged in from server side use below command

Netapp> igroup show -v

   Verify luns are mapped to the corresponding igroup

   Verify whether correct host type is mentioned while creating igroup and lun

   Verify whether correct iqn/wwpn number is added to igroup

   Verify zoning is properly configured from switch side, if it is FCP protocol


Q. How to create the LUN for linux server?

lun create –s size –t linux /vol/vol1/lunname


Q. How to create qtree and provide the security?

Netapp>qtree create /vol/vol1/qtreename

Netapp>qtree security /vol/vol1/qtree unix|ntfs|mixed


Q. How to copy volume filer to filer?

ndmpcopy or snapmirror


Q. How to resize the aggregate?

Netapp> aggr add AggName no.of.disk


Q. How to increase the volume?

Traditional Volume

vol add VolName no.of.disk

Flexible Volume

vol size VolName +60g


Q. What is qtree?

qtree is Logical partition of the volume.


Q. What is the default snap reserve in aggregate?

5%


Q. What is snapshot?

A Snapshot copy is a read-only image of a traditional or FlexVol volume, or an aggregate, that captures the state of the file system at a point in time.


Q. What are the raid groups Netapp supporting?, what is the difference between them?

Supported RAID types:

  • Raid-4
  • Raid-6
  • Raid-Dp

Q. What are the protocols you are using?

Say some protocols like NFS, CIFS, ISCSI and FCP


Q. What is the difference between iscsi and fcp?

Iscsi-sending block through. iSCSI does not required dedicated network, it will work on existing network also. it work’s an TCP/IP.

Fcp-send through fibre medium. Required an dedicated FC network.  Performance is so high compare to the iSCSI


Q. What is the iscsi port number?

3260


Q. What is the difference between ndmp copy and vol copy?

Ndmp copy –network data management protocol(used for tape backup)

Vol copy – is used to transfer volume to same or another aggregate


Q. What is the difference between ONTAP 7 & 8?

In ONTAP 7 the individual aggregate is limited to maximum of 16 TB. Where ONTAP 8 supports the new 64 bit aggregate and hence the size of the individual aggregate extends to 100 TB.


Q. If you were troubleshooting and wanted to look at SnapMirror log files, what is the path to these files?

/vol/vol0/etc/log/


Q. Which statement describes the results of the SnapMirror resynce command?

Resynchronization finds the newest common snapshot shared by the two volumes or qtree, and removes all newer information on the storage system on which the command is run.


Q. What are the steps need to perform to configure SnapMirror?

The SnapMirror configuration process consists of the following four steps:

Refer Topic

Install the SnapMirror license on the source and destination systems:

license add <code>

On the source, specify the host name or IP address of the SnapMirror destination systems you wish to authorize to replicate this source system.

options snapmirror.access host=dst_hostname1,dst_hostname2

For each source volume or qtree to replicate, perform an initial baseline transfer. For volume SnapMirror

restrict the destination volume first: vol restrict dst_vol

Then initialize the volume SnapMirror baseline, using the following syntax on the destination:

snapmirror initialize -S src_hostname:src_v

oldst_hostname:dst_vol

For a qtree SnapMirror baseline transfer, use the following syntax on the destination:

snapmirror initialize –S src_hostname:/vol/src_vol/src_qtree

dst_hostname:/vol/dst_vol/dst_qtree


Q. While doing baseline transfer you’re getting error message. What are the troubleshooting steps you’ll do?

Check both the hosts are reachable by running “ping” command

Check whether the TCP port 10566 & 10565 are open from firewall

Check whether the snapmirror license are installed in both filers


Q. Explain the different types of replication modes..?

The SnapMirror Async mode replicates Snapshot copies from a source volume or qtree to a destination. It will support to replicate more than 800Kms Long. volume or qtree. Incremental updates are based on a schedule or are performed manually using the snapmirror update command. Async mode works with both volume SnapMirror and qtree SnapMirror.

SnapMirror Sync mode replicates writes from a source volume to a destination volume at the same time it is written to the source volume. SnapMirror Sync is used in environments that have zero tolerance for data loss. it will note support more then 300Kms long.

SnapMirror Semi-Sync provides a middle-ground solution that keeps the source and destination systems more closely synchronized than Async mode, but with less impact on performance.


Q. How do you configure multiple path in Snapmirror?

Add a connection name line in the snapmirror.conf file

/etc/snapmirror.conf

FAS1_conf = multi (FAS1-e0a,FAS2-e0a) (FAS1-e0b,FAS2-e0b)


Q. Explain how De-Duplication works?

In the context of disk storage, De-duplication refers to any algorithm that searches for duplicate data objects (for example, blocks, chunks, files) and discards those duplicates. When duplicate data is detected, it is not retained, but instead a “data pointer” is modified so that the storage system references an exact copy of the data object already stored on disk. This De-duplication feature works well with datasets that have lots of duplicated date (for example, full backups).


Q. What is the command used to see amount of space saved using De-duplication?

df –s <volume name>


Q. Command used to check progress and status of De-duplication?

sis status


Q. How do you setup Snapvault Snapshot schedule?

pri> snapvault snap sched vol1 sv_hourly 22@0-22

This schedule is for the home directories volume vol1

Creates hourly Snapshot copies, except 11:00 p.m.

Keeps nearly a full day of hourly copies


Q. What is metadata?

Metadata is defined as data providing information about one or more aspects of the data,

  1. Inode file
  2. Used block bitmap file
  3. Free block bitmap file

 

Q. How do you shutdown filer through RLM?

ssh “rlm ip address”

RLM_Netapp> system power on


Q. After creating LUN (iSCSI) & mapped the LUN to particular igroup, the client not able to access the LUN. What are the trouble shooting steps you take?

  • Check whether IQN number specified is correct
  • Check whether the created LUN is in “restrict” mode
  • Check the iscsi status
  • Un-map and map the LUN once again
  • Check Network connectivity communication

Q. In CIFS how do you check who is using most?

cifs top


Q. What is VServer..?

A Vserver is defined as logical container which holds the volumes. A 7 mode vfiler is called as a vserver in Clustered mode .  


Q. What is junction path..?

This is a new term in cluster mode and this is used for mounting.Volume junctions are a way to join individual volumes together into a single, logical namespace to enable data access to NAS clients.


Q. How to check cifs performance statistics.?

cifs stat


Q. What do you do if a customer reports a particular CIFS share is responding slow?

Check the r/w using “cifs stat” & “sysstat -x 1”.

If disk & cpu utilization is more then problem is with filer side only.

CPU utilization will be high if more disk r/w time, i.e.,during tape backup & also during scrub activities.


Q. What is the diff bet cf takeover and cf force takeover?

If partner shelf power is off, if you try to takeover it will not take. if you do as force using (-f) it will work


Q. What is LIF.?

LIF ( Logical interface) :

As the name suggest its a logical interface which is created from physical interface of NetApp controllers.


Q. What is infinite volumes..?

NetApp Infinite Volume is a software abstraction hosted over clustered Data ONTAP


Q. What is the difference between NAS & SAN?

The main difference between NAS and SAN is that NAS is an Ethernet based while SAN is Fabric based.

NAS- Network Attached Storage

It enters data on file level and develops space to host in the form of folder of shared networks.

SAN- Storage Area Network

It enters data on block level and develops space to host in the form of a disk.


Q. What is Network Attached Storage (NAS)?

Network Attached Storage is nothing but a hard disk storage, which is having its own network address and not being attached to the computer department, which serves applications to a user’s of network’s workstation. Both application files and programming can be served faster, this is done by removing management and storage access from the department server because they are not competing for the resources of the same processor. The NAS device is assigned an IP address and attached to the local area network. The file request is sent to the NAS file server by the main server. NAS consists of multi disk RAID systems, software for mapping and configuring file locations to the NAS and hard disk storage.


Q. What is Storage Area Network (SAN)?

SAN is a special purpose high speed network,  which connects various kinds of data storage devices with data servers on behalf of the users of larger networks. SAN supports retrieval and archival of data, restore and backup, disk mirroring, sharing of data and data migration from one device to another. SAN is a part of the overall network of resources of computing for an enterprise. It can incorporate subnet works with NAS systems.


Q. How to improve the Netapp storage performance?

  • If volume/lun present in ATA/SATA harddisk aggregate, then the volume can be migrated to FC/SAS disk aggregate.
  • For NFS/CIFS instead of accessing from single interface, multi mode vif can be configured to get better bandwidth and fault tolerance.
  • Always advised to keep aggr/vol utilization below 90%.
  • Avoid doing multiple volume backup in single point of time.
  • Aggr/volume/lun reallocation can be done to re–distribute the data to multiple disk for better striping performance.
  • Schedule scrubbing and deduplication scanning after business hours.
  • Avoid connecting different types of shelf in a same loop.
  • Avoid mixing up different speeds of disk and different types of disk in a same aggregate.
  • Always keep sufficient spare disk to replace incase of disk failure. Because reconstruction time will take more time and cause negative performance.
  • Keep the advised version of firmware/software which is recommended by netapp.
  • Better to have nearstore functionality to avoid backing up data from source filer.

Q. What is an HBA?

HBA is a Host Bus Adapters which are needed to connect the server to the storage.


Q. What is storage virtualization?

Storage virtualization is the process of uniting multiple devices of network storage into a single storage unit.


Q. What is zoning?

It is a managed  service of fabric which can be used to create logical subsets of devices within a SAN. It allows portioning of resources for access control and management purpose.


Q. Explain the different types of replication modes?

SnapMirror semi-sync: It offers a middle ground solution which keeps the destination and source systems more synchronized than Async mode, but it will focus less on performance.

SnapMirror Sync mode: At the same time, It performs write function from a source volume to a destination volume. This mode is used in a case,  where there is zero tolerance for data loss.

SnapMirror Async mode: It transfers snapshot copies from either qtree or source volume to a destination. Using the snapmirror update command, rising updates are performed manually or based on a schedule. It performs with both Qtree snapmirror and volume snapmirror.


Q. What are the raid groups netapp supporting?, what is the difference between them?

Raid_dp(double parity,diagonal parity) ,raid4(striping&dedicated parity)


Q. What is the difference between ndmp copy and vol copy?

Ndmp copy –network data management protocol(used for tape backup)

Vol copy – is used to transfer volume to same or another aggr

http://netapplines.blogspot.in/2012/05/comparison-of-vol-copy-ndmpcopy-and.html


Q. What are the steps need to perform to configure SnapMirror?

The SnapMirror configuration process consists of the following four steps:

a) Install the SnapMirror license on the source and destination systems: license add <code>

b) On the source, specify the host name or IP address of the SnapMirror destination systems you wish to authorize to replicate this source system.

options snapmirror.access host=dst_hostname1,dst_hostname2

c) For each source volume or qtree to replicate, perform an initial baseline transfer. For volume SnapMirror,

restrict the destination volume first: vol restrict dst_vol

Then initialize the volume SnapMirror baseline, using the following syntax on the destination:

snapmirror initialize -S src_hostname:src_v

oldst_hostname:dst_vol

For a qtree SnapMirror baseline transfer, use the following syntax on the destination:

snapmirror initialize –S src_hostname:/vol/src_vol/src_qtree

dst_hostname:/vol/dst_vol/dst_qtree

d) After the initial transfer completes, set the SnapMirror mode of replication by creating the

/etc/snapmirror.conf file in the destination’s root volume.

For reference:

http://netapplines.blogspot.in/2012/01/snapmirror-schedule-configuration.html

http://netapplines.blogspot.in/2011/11/snapmirror-primary-conf.html

http://netapplines.blogspot.in/2011/11/snapmirror-secondary-conf.html


Q. what is degraded mode? If you don’t have parity for failed disks then?

If the spare disk is not added within 24hours,then filer will be shutdown automatically to avoid further disk failures and data loss.


Q. Did you ever do ontap upgrade? From which version to which version and for what reason?

Yes i have done ontap upgrade from version 7.2.6.1 to 7.3.3 due to lot of bugs in old version.


Q. How do you create a lun?

lun create -s <lunsize> -t <host type> <lunpath>


Q. How do you monitor the filers?

Using DFM(Data Fabric Manager) or also using SNMP you can monitor the filer. Using any monitoring systems like .i.e.Nagios


Q. What are the prerequisites for a cluster?

  • cluster interconnect cable should be connected.
  • shelf connect should be properly done for both the controllers with Path1 and Path2
  • cluster license should be enabled on both the nodes
  • Interfaces should be properly configured for fail over
  • cluster should be enabled

Q. Which two cp types would indicate a busy storage system? (Choose two).

cp_from_log_full

cp_from_cp

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