Module 10 Clones and Thin Clones 18pages

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    Disk cloning is often thought of as the process of copying the contents of one

    computer hard disk to another disk or to an "image" file. Often, the contents of the

    first disk are written to an image file as an intermediate step, and the second disk is

    loaded with the contents of the image. This procedure is also useful when moving to

    a larger capacity disk or to restore to a virgin installation.

    In the case of the PS Storage array the clone of a volume is an exact image of the

    original volume at the time the cloning was executed or started. The new clone

    volume is immediately available and takes up free space equal to the original volume.

    There is no association or dependencies between the original volume and the clone

    volume. Once the clone has been created, it has no continuing relationship with the

    original volume.

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    Create a new volume by copying an existing object:

    From base volume, snapshot or replica

    Non-shared storage (unlike snapshot) once the copy is complete

    Full volume operations once the available copy is complete

    Cloning process:

    Coordinated (like snapshot) creation

    Instant creation and accessibility (while copy is occurring)

    Background copy

    Space balancing enforcement

    Uses:

    Use a replica

    Replicated system deployments

    Test systems

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    Uses for disk cloning include:

    Reboot and restore a technique in which the disk of a computer is automatically

    wiped and restored from a "clean", master image, which should be in full working

    order and should have been swept for viruses. The reboot and restore process can

    either take place irregularly when a computer shows signs of malfunctioning, on aregular basis (e.g., nightly) or even, in some cases, every time a user logs off, which is

    the safest approach (although that does involve some downtime).

    Provisioning new computers Provisioning with a standard set of software so that a

    new user is ready to go straight away with a complete application suite and does not

    have to waste time installing individual applications. This is often done by original

    equipment manufactures and larger companies.

    Full system backup A user may create a comprehensive backup of their operating

    system and installed software.

    System Recovery - An OEM can provide media that can restore a computer to its

    original factory software configuration

    Transfer to another user A system sold or given to another person may be reset by

    reloading a known, previously-saved image that contains no personal files or

    information.

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    Thin clones may only be created when a special template volume is first created. By

    sharing data between the template and the thin clone, space is saved over a

    traditional clone, especially when making many clones of the same volume.

    Template/thin clone relationship provides a better way to manage many clones of

    the same volume. because they share data. Slices must be on the same members

    and they are moved together.

    Typical uses cases :

    Boot Volumes

    A master boot volume is created as a template.

    A thin clone is created for every client machine.

    Only the data the client stores will take up space.

    Cloning a large data volume

    A large data volume can be made into a template.

    A thin clone can be created and changes made to that volume.

    Since most of the data is shared, a large amount of space is saved

    Thin Clones introduce two new volume types;. A Template, volume, which is the

    main volume where a majority of the data is stored and is shared by the thin clones.

    A Thin clone volume, where only data associated with that volume is stored, all

    common data is stored on the template, This provides a better way to manage many

    clones of the same volume. The one dependencies is that the Thin clone location is

    dependent on the template, where the template goes the thin clones go with it.

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    A template volume is a volume that is converted to a template. During the

    conversion the volume will be placed offline and read-only.

    Once converted, any free volume reserve above the thin min reserve is released.

    Snap reserve also reduced accordingly but no snapshots deleted. Any active

    snapshot or replication schedules are suspended.A template may not be converted back into a volume until all thin clones are

    deleted/detached.

    Once the volume is converted to a template, thin clones can now be created from

    the Template volume

    Initially, a template volume and thin clone are identical in reported size and content.

    Because the group allocates space to the new thin clone in the same way it allocates

    space to a new standard, thin provisioned volume, only the minimum volume reserve

    is consumed from free pool space.

    You can also delete or modify data that the thin clone shares with the template

    volume. However, the data in the template volume is always preserved because a

    template volume is read-only. Group Manager tracks the amount of data that is

    shared between each thin clone and template volume and displays it in the Volume

    Status window.

    Quiz: Why isnt there an option to create a template volume from scratch?

    Answer: Making a volume a template only makes sense if the volume has data in it.

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    New volume attribute denotes whether a volume is a thin clone.

    Thin clones are initially created with no volume reserve in use. They share all data

    with their parent template.

    Since they are thin volumes though, they still have a thin min reserve. Initially this,

    plus the snap reserve, is the only free space they use.

    As data is written to the thin clone, new pages are allocated for the thin clone and

    volume reserve is used. So when initiators write data to a thin clone, space is

    consumed from free volume reserve. As needed, the group allocates additional

    volume reserve to the thin clone, up to the maximum in-use space setting for the

    thin clone.

    The thin clones are considered attached to the template volume and cannot exist

    without the template volume, similar to how snapshots depend on the base volume.

    The group always maintains and shows the dependency of a thin clone on a template

    volume. If you expand Volumes in the far-left panel, you can choose to display all

    volumes in alphabetical order or display thin clones under the template volume on

    which they depend.

    May be detached from the template to become standalone volumes.

    Quiz: How many thin clones can you create on a template?

    Answer: 1023

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    Converts a volume to a template; When you convert a standard volume to a template

    volume, the template volume will be thin provisioned, read-only, and offline. You can

    later set the volume online, if desired.

    Converts a template to a volume; You cannot convert a template volume to a

    standard volume if thin clones are attached to the template volume or if the templatevolume is configured for replication. You must disable replication before you can

    convert a template volume to a volume. Space used to store template replicas on

    secondary may become unmanaged if you convert a template volume to a volume.

    Create a thin clone from a template, creates an associated volume that uses the

    shared data in the template volume

    Detaching a thin clone from a template volume breaks the dependency between the

    thin clone and the template volume. Detaching a thin clone from a template, creating

    a standalone volume. The free space this new volume takes up is equal to shared

    pages plus the allocated pages (plus the snap reserve). If you detach a thin clone

    from a template volume, the thin clone is converted to a standard volume and no

    longer shares space with the template volume. Therefore, when you detach a thinclone, the volume reserve for the thin clone increases by the amount of space the

    thin clone shares with the template volume. If you detach a thin clone from a

    template volume that is bound to a member or has a RAID preference, the resulting

    volume will not inherit the binding or the RAID preference. Restriction: You cannot

    detach a thin clone if replication is enabled for the thin clone.

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