Nodetool snapshot runs as this creates snapshots for all tables in the keyspace. It is not recommended to set it to false, unless there is a good backup and recovery strategy in place. The default setting for the auto_snapshot flag in /etc/scylla/scylla.yaml file is true. The data in a table can also be deleted, which is different from being truncated.
A table, on the other hand, can be either truncated or dropped. Note that a keyspace cannot be truncated. This option is enabled out of the box and is controlled by the auto_snapshot flag in the /etc/scylla/scylla.yaml configuration file. As dropping a keyspace involves dropping tables within that keyspace, these actions will invoke auto snapshots as well. Therefore, even as the database is moving on, once the snapshot hard links are created, the content of the data files can be copied off to another storage and serve as the foundation for a table, keyspace, or entire database restore (on that node, as this backup and restore process is node specific).Īpart from planned backup procedure described above, and as a safeguard from accidental loss of data, the Scylla database includes an optional creation of an automatic snapshot every time a table is dropped or truncated. If even one pointer exists, the file will remain. Only after all of the pointers are removed, the actual file is removed. The compaction process removes files in the data directory, but the snapshot hard links will still be pointing to the old files. If snapshots (hard links) were created to existing SSTables on disk they are preserved even if table data is eventually stored in one or more of the new SSTables. The new files are consolidated following compaction, which merges table’s data into one or more SSTable files (depending on the compaction strategy). When data in database changes and data is written to disk, it is written as a new file. It is important to understand that SSTables are immutable and as such are not re-written in the same file. As mentioned above, snapshots are hard links to SSTables on disk. Scylla, like Cassandra, requires Unix-like storage (such is also a file system supported by Linux). Materialized views do exist in Scylla but they are not called snapshots. With Scylla, snapshots are hard links to data files.
#DIFFERENCE BETWEEN SNAPSHOT AND MAILIST UPGRADE#
Upgrade your server to higher or different specs with all installed softwares and their configsĪMIs can be publicly shared across AWS accounts.If you come from RDBMS background you should not confuse snapshots with the notion of materialized views (as they are sometimes called snapshots in that area of technology). configured to connect to `Splunk, has some monitoring and observability softwares installed, has docker installed, or it's configured to connect Puppet or Chef in startup)ĪMIs could be used to deploy your applications in different regions easily. Standard company's AMIs that have all installed prerequisites softwares that simplifies the process of deployment (e.g. It is incremental backup operation which means every time you take a snapshot of a volume, it will add only the new changes added/introduced to the volume since your last backup (not entire backup), that saves backup time, space and ultimately the cost.Ĭhange the type of volume, for example you have traffic or reads and writes and need to increase IO operations so you change from gp2 to io1 with higher IOPsįor disaster recovery in case current running EC2 instance corrupted and couldn't run for no reason. Snapshots can be used to backup drives/volumes. Launch a new Instance (same installed softwares and configs, different specs) EC2 <- EBS Volume (Boot) + EBS VolumeĪMI (Combined snapshots of all volumes, snapshot must have boot volume)
With Packer, you can build automated machine images including AMIs for EC2, VMDK/VMX files for VMware, OVF exports for VirtualBox, etc. Snapshot is a point in time backup of specific volume while AMI is is backup of the entire EC2 instance that might have multiple attached volumes, exactly like virtual machines. EBS Volume is the underlying disk behind EC2.
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