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  2. Drive letter assignment - Wikipedia

    en.wikipedia.org/wiki/Drive_letter_assignment

    If there is more than one extended partition in a partition table, only the logical drives in the first recognized extended partition type are processed. Some late versions of the DR-DOS IBMBIO.COM provide a preboot config structure, holding bit flags to select (beside others) between various drive letter assignment strategies.

  3. Primary key - Wikipedia

    en.wikipedia.org/wiki/Primary_key

    In the relational model of databases, a primary key is a designated attribute that can reliably identify and distinguish between each individual record in a table.The database creator can choose an existing unique attribute or combination of attributes from the table (a natural key) to act as its primary key, or create a new attribute containing a unique ID that exists solely for this purpose ...

  4. Device mapper - Wikipedia

    en.wikipedia.org/wiki/Device_mapper

    The device mapper is a framework provided by the Linux kernel for mapping physical block devices onto higher-level virtual block devices.It forms the foundation of the logical volume manager (LVM), software RAIDs and dm-crypt disk encryption, and offers additional features such as file system snapshots.

  5. Many-to-many (data model) - Wikipedia

    en.wikipedia.org/wiki/Many-to-many_(data_model)

    In this case the logical primary key for AB is formed from the two foreign keys (i.e. copies of the primary keys of A and B). In web application frameworks such as CakePHP and Ruby on Rails, a many-to-many relationship between entity types represented by logical model database tables is sometimes referred to as a HasAndBelongsToMany (HABTM ...

  6. Logical block addressing - Wikipedia

    en.wikipedia.org/wiki/Logical_block_addressing

    Logical block addressing (LBA) is a common scheme used for specifying the location of blocks of data stored on computer storage devices, generally secondary storage systems such as hard disk drives. LBA is a particularly simple linear addressing scheme; blocks are located by an integer index, with the first block being LBA 0, the second LBA 1 ...

  7. LIO (SCSI target) - Wikipedia

    en.wikipedia.org/wiki/LIO_(SCSI_target)

    The Linux-IO Target (LIO) is an open-source Small Computer System Interface (SCSI) target implementation included with the Linux kernel. [ 1 ] [ better source needed ] Unlike initiators, which begin sessions, LIO functions as a target, presenting one or more Logical Unit Numbers (LUNs) to a SCSI initiator , receiving SCSI commands, and managing ...

  8. DRBD - Wikipedia

    en.wikipedia.org/wiki/DRBD

    DRBD layers logical block devices (conventionally named /dev/drbdX, where X is the device minor number) over existing local block devices on participating cluster nodes. Writes to the primary node are transferred to the lower-level block device and simultaneously propagated to the secondary node(s). The secondary node(s) then transfers data to ...

  9. Referential integrity - Wikipedia

    en.wikipedia.org/wiki/Referential_integrity

    A table (called the referencing table) can refer to a column (or a group of columns) in another table (the referenced table) by using a foreign key. The referenced column(s) in the referenced table must be under a unique constraint, such as a primary key. Also, self-references are possible (not fully implemented in MS SQL Server though [5]).