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Through packet writing, which uses the Universal Disk Format (UDF) file system, these discs often use a file system that permits additional files, and even revised versions of a file by the same name, to be recorded in a different region of the disc. To the user, the disc appears to allow additions and revisions until all the disk space is used.
In computer science, write-ahead logging (WAL) is a family of techniques for providing atomicity and durability (two of the ACID properties) in database systems. [1]A write ahead log is an append-only auxiliary disk-resident structure used for crash and transaction recovery.
It can be used to create/remove Host Protected Area (HPA) (using command SET MAX) and create/remove DCO hidden area (using command DCO MODIFY). It also can do other functions on the DCO. Data Synergy's freeware ATATool utility can be used to detect a DCO from a Windows environment. Recent versions allow a DCO to be created, removed or frozen. [3]
In data storage, disk mirroring is the replication of logical disk volumes onto separate physical hard disks in real time to ensure continuous availability. It is most commonly used in RAID 1 . A mirrored volume is a complete logical representation of separate volume copies.
From the MongoDB 2.6 release onward, the binaries for the official MongoDB RPM and DEB packages bind to localhost by default. From MongoDB 3.6, this default behavior was extended to all MongoDB packages across all platforms. As a result, all networked connections to the database are denied unless explicitly configured by an administrator. [59]
However, modern NoSQL databases often incorporate advanced features to optimize query performance. For example, MongoDB supports compound indexes and query-optimization strategies, Cassandra offers secondary indexes and materialized views, and Redis employs custom indexing mechanisms tailored to specific use cases.
The central concept of a document-oriented database is the notion of a document.While each document-oriented database implementation differs on the details of this definition, in general, they all assume documents encapsulate and encode data (or information) in some standard format or encoding.
This behavior can be overridden using vgconvert --pvmetadatacopies. If the LVM can not read a proper header using the first copy, it will check the end of the volume for a backup header. Most Linux distributions keep a running backup in /etc/lvm/backup, which enables manual rewriting of a corrupted LVM head using the vgcfgrestore command.