STORAGE SNAPSHOT

What is storage snapshot?

1. A storage snapshot can be defined as a set of pointers to denote the data stored on a storage device. 
2. This storage device could be a disk drive, a tape or SAN.
3. This snapshot is treated by the computer as a complete backup of data.
4. In simple words, Snapshot is a point in time image of the data
5. Storage snapshot provides easy access to stored data and further speeds up the data recovery process.
6. Storage snapshot is used for data backup in event of failure of the data storage.

What techniques/technologies,types in storage snapshot.

 http://searchdatabackup.techtarget.com/tip/Using-different-types-of-storage-snapshot-technologies-for-data-protection

• Copy-on-write
• Redirect-on-write
• Clone or split-mirror
• Copy-on-write (COW) with background copy
• Incremental
• Continuous data protection (CDP)

1. Copy-on-write (COW): Here data is copied into a pool of allocated storage. The major limitation of this method is that it impacts the performance of original data.
2. Redirect-on-write: It is somewhat similar to COW. It offers efficietn snapshosots in terms of performance and space as it does not deal in double writing.
3. Split-mirror: In this technique, a physical clone is created of the data which resides on different storage space.

Can snapshot be used as Backup?

 

When does storage snapshot technology works best?

 

Difference between storage snapshot and backup?

In storage, if a volume is 100GB and snap-pool is 20GB, and vdisk size is 200GB. How the snapshots size is stored. what is snap-data, shared data and unique data in our storage.

Where will be the metadata of the snapshot stored.

What happens if we delete the master volume of the snapshot, how will we get the data, where will it point to. 

What is the difference between backup and Replication?

Rollback snapshot

File snapshots

Block level snapshots

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What is Metadata?

1. Metadata is something that helps to better describe the data you are trying to remember. 
2. Metadata is data that provides information about other data. 
3. For example I have a file named "program". 
4. Metadata of the file is name of the file, size of the file, location of the files, author of the life etc., 
5. Data which is used to find the actual data is called the metadata.

There are 3 types of metadata

• Descriptive metadata --> It describes a resource for purposes such as discovery and identification. It can include elements such as title, abstract, author and keywords.

• Structural metadata--->It is the metadata about containers of data and indicated how compound objects are put together. For example how pages are ordered to form chapters. It describes the types, versions, relationships and other characteristics of digital materials.

•  Administrative metadata--> It provides information to help manage a resource, such as when and how it was created, file type and other technical information and who can access it. 

Where is metadata stored in our storage

Which type of metadata is used in our storage

Can we see the metadata

Writeback and write through

Replication and Remote snapshot replication

volume copy and how the size in vdisk is effected

Scrub, parity ,medium errors, verify, DSD, slot affinity

Raid levels, s/w and H/w raids

Different disks, disk speed, enclosure speed

FC, SAS and iscsi , how it works and which is best

 Switches, zoning

data mining and data cloning

DH products