Free Practice Questions for Netapp NS0-155 Exam

Both ‘warn you that there are no available spares from the proper pool’ and ‘halt after 24 hours if spare disk are not added to the proper pool’ are correct answers. However, since Data ONTAP alerts you first, 'warn you that there are no available spares' is the best answer.

https://library.netapp.com/ecm/ecm_download_file/ECMP1196912

SyncMirror is essentially a RAID-1 mirror; hence the name. The best practice is to mirror storage of equal performance; i.e. identical RAID groups and disk sizes (number of spindles, IOPS). If you were to mirror two storage devices of different performance, the slower device would be the limiting factor.

http://www.netapp.com/us/media/tr-3326.pdf

http://backdrift.org/man/netapp/man5/na_snapmirror.conf.5.html

http://hd.kvsconsulting.us/netappdoc/733docs/html/ontap/onlinebk/GUID-47724B21-7C7E-4AC9-A497-9505B42C27AF.html

With SnapMirror Sync and SnapMirror Semi-Sync, changes to the source volume do not show up immediately on the destination volume, even though the changes have been replicated. The changes are first shown after the source system creates an automatic Snapshot copy of the source volume.

Snapshot copies created on the source volume are immediately propagated to the destination volume. The automatic Snapshot copies are created every three minutes by default.

To change the interval for automatic Snapshot copies, change the visibility_interval in the

snapmirror.conf file; however, performance can degrade if set to a smaller interval because frequent

Snapshot copies cause additional processing such as cache consistency checking on the destination system.

There is also a disadvantage in setting this to a large value. When the connection between the systems has an outage and SnapMirror goes into asynchronous mode, SnapMirror uses the last common Snapshot copy to transition into synchronous mode. This means that all data from the last valid common Snapshot copy will need to be replicated from the source to the destination storage system. If the visibility_interval is set to a large value, a large amount of data might have to be transferred and it might take longer time for SnapMirror to transition into synchronous mode. For these reasons, keep the default value of three minutes.

visibility_interval

The value for this argument is a number optionally followed by the suffixes: s (seconds), m (minutes) or h (hours). If a suffix is not specified, value is interpreted as seconds. This argument controls the amount of time before an automatic snapshot is created on the source volume that is synchronously mirrored. The value is the number of seconds between automatically created snapshots. The default value is 3 minutes. A small number here can negatively affect the performance of the mirror. This argument is ignored for asynchronous mirrors.

visibility_interval={xs | xm | xh}

Determines the amount of time before an automatic Snapshot copy is created on the source volume that is being replicated using synchronous or semi-synchronous SnapMirror. When replicating synchronously or semisynchronously, using SnapMirror, changes to the source volume do not show immediately on the destination volume, even though the changes have been replicated. The changes are shown only after the source system takes an automatic Snapshot copy of the source volume. This event occurs every three minutes by default.

You can change the interval for automatic Snapshot copies, but performance can degrade if you set smaller intervals because Snapshot copies are taken more often. The smallest interval you can set is 30 seconds.

Note: The s, m, and h suffixes specify seconds, minutes, and hours, respectively.

https://library.netapp.com/ecmdocs/ECMP1196979/html/man1/na_snapvault.1.html

The snapvault command has a number of subcommands. The set of subcommands differs on the primary and secondary.

On the primary, the subcommands allow users to configure and manage a set of snapshots for potential replication to the secondary, to abort replication transfers to the secondary, to check status, to restore data from the secondary, and to release resources when a primary qtree will no longer be replicated to a secondary.

On the secondary, the subcommands allow users to configure and manage the replication of primary paths to secondary qtrees, to configure and manage the snapshot schedules which control when all the qtrees in a secondary volume are updated from their respective primary paths and how many snapshots to save, to abort transfers, to check status, and to release resources preserved to restart backups from a restored qtree.

This option causes the file system to remain the same size and not grow or shrink when a SnapMirrored volume relationship is broken, or when a vol add is performed on it. This option is automatically set to be on when a volume becomes a SnapMirrored volume. It will remain on after the snapmirror break command is issued for the volume. This allows a volume to be SnapMirrored back to the source without needing to add disks to the source volume. If the volume size is larger than the file system size, turning off this option will force the file system to grow to the size of the volume. The default setting is off.

http://wafl.co.uk/vol-2/#sthash.DbEHR4YS.dpuf

snap restore [ -A | -V ] [ -f ] [ -t vol | file ] [ -s snapshot_name ]

[ -r restore_as_path ] vol_name | restore_from_path

See more at: http://wafl.co.uk/snap/#sthash.nJiEwxGV.dpuf

https://communities.netapp.com/servlet/JiveServlet/previewBody/4803-102-1-6405/tr-3548.pdf

It is important to remember that this is the case only when a complete site is lost. In the case of a failed controller at one of the sites, a normal cluster failover occurs. Due to the operation of SyncMirror, there is also added protection from multidrive or complete shelf failures. When a storage controller fails in an active-active configuration, the partner detects the failure and automatically (if enabled) performs a takeover of the dataserving responsibilities from the failed controller. Part of this process relies on the surviving controller being able to read information from the disks on the failed controller. If this quorum of disks is not available, then automatic takeover won’t be performed. In a MetroCluster configuration, manually executing a single command will allow a takeover to occur in spite of the lack of a quorum of disks. This "forced takeover" process breaks the mirrored relationships in order to bring the failed controller’s volumes on line.

forcetakeover -d is very dangerous. Not only can it cause data corruption, if not used carefully, it can also lead to a situation where both the node and its partner are operational (split brain). As such, it should only be used as a means of last resort when the takeover and forcetakeover commands are unsuccessful in achieving a takeover. The operator must ensure that the partner node does not become operational at any time while a node is in a takeover mode initiated by the use of this command. In conjunction with RAID mirroring, it can allow recovery from a disaster when the two nodes in the HA pair are located at two distant sites.