Windows Server 2012 - File System

In Windows Server 2012 a new file system it is presented with is caller Resilient File System (ReFS).

The key attributes of ReFS include −

• Maintaining a high level of data availability and reliability, even when the individual underlying storage devices experience failures.

• Providing a full, end-to-end resilient architecture when used in conjunction with Storage Spaces. When used together, ReFS and Storage Spaces provide enhanced resiliency to storage device failures.

The significant functionality included with ReFS is described below −

• Integrity − ReFS stores data in a way that protects it from many of the common errors that can normally cause data loss. When ReFS is used in conjunction with a mirror space or a parity space, detected corruption — both metadata and user data, when integrity streams are enabled — can be automatically repaired using the alternate copy provided by Storage Spaces. In addition, there are Windows PowerShell cmdlets (Get-FileIntegrity and Set-FileIntegrity) that you can use to manage the integrity and disk scrubbing policies.

• Availability − ReFS prioritizes the availability of data. Historically, file systems were often susceptible to data corruption that would require the system to be taken offline for repair. With ReFS, if corruption occurs, the repair process is both localized to the area of corruption and performed online, requiring no volume downtime. Although rare, if a volume does become corrupted or you choose not to use it with a mirror space or a parity space, ReFS implements salvage, a feature that removes the corrupt data from the namespace on a live volume and ensures that good data is not adversely affected by non-repairable corrupt data. Because ReFS performs all repair operations online, it does not have an offline chkdsk command.

• Scalability − As the amount and size of data that is stored on computers continues to rapidly increase, ReFS is designed to work well with extremely large data sets — petabytes and larger — without performance impact. ReFS is not only designed to support volume sizes of 2^64 bytes (allowed by Windows stack addresses), but ReFS is also designed to support even larger volume sizes of up to 2^78 bytes using 16 KB cluster sizes. This format also supports 2^64 – 1-byte file sizes, 2^64 files in a directory and the same number of directories in a volume.

• Proactive Error Correction − The integrity capabilities of ReFS are leveraged by a data integrity scanner, which is also known as a scrubber. The integrity scanner periodically scans the volume, identifying latent corruptions and proactively triggering a repair of that corrupt data.

When the metadata for a ReFS directory is corrupted, subfolders and their associated files are automatically recovered. ReFS identifies and recovers the files while ReFS remains online. Unrecoverable corruption of the ReFS directory metadata affects only those files that are in the directory in which the corruption has occurred.

ReFS includes a new registry entry, RefsDisableLastAccessUpdate, which is the equivalent of the previous NtfsDisableLastAccessUpdate registry entry. The new storage command lets in Windows PowerShell are available (Get-FileIntegrity and SetFileIntegrity) for you to manage the integrity and disk scrubbing policies.