Consider buying a storage array that supports both Fibre Channel and iSCSI, so that you have the flexibility to switch from one to the other or implement both. Support for Fibre Channel and iSCSI on the same array.
Sql server vdi wait update#
Doing so requires three block I/Os and an update to a link, whereas the first approach requires only one block I/O.This difference becomes significant for disk performance as large numbers of blocks are updated. In Figure B, block D is moved from the current block to a new block so that the new contents of D can be written to D's old location. Copy-on-write requires more data movement and overhead on the storage array's part than the first approach. This approach, which Figure B shows, is often called copy-on-write.
Sql server vdi wait free#
The second methodology is to copy the snapshot block to a free block, then overwrite the block that was just copied.
Of the two approaches, this is the more efficient because it requires only one block I/O operation to write the new block and one update to a pointer. Vendors use one of two basic methodologies for handling snapshots after data has been modified.The first methodology, which Figure A shows, is to leave the snapshot block alone and use a free block to write the modified block information. Snapshots work about the same in all storage arrays.The idea is to freeze all the blocks of data in a database and the structure of the data being captured at a point in time. These guidelines can help you narrow down the type of storage array you need to house your SQL Server databases. Storage arrays are available in a wide spectrum of capacities and capabilities, and sorting through the options can be confusing.
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