What are the primary differences between NTFS and ReFS file systems?
Despite the potential advantages of the newer ReFS file systems, it was never intended as a replacement for NTFS, but rather a complement. While the design of ReFS means that it optimizes disk performance, it lacks hard links, which means it can’t be used to run operating systems or certain applications.
When helping your customers decide whether to implement an NTFS or ReFS file system, it’s important to take into consideration the ways the two systems differ. Though NTFS and ReFS are designed to include a number of similar features, the way each operates primarily differs in three key areas: reliability, performance, and scalability.
NTFS makes use of checkpoints and log files, which means that in the case of a system failure, the file structure can restore the system to a previously logged version. The journaling file system of NTFS—which tracks changes to the disk volumes—does something similar. In the event of a failed data migration or a system crash, NTFS provides a high degree of reliability and data safety by allowing you to return the disk infrastructure to a previous uncorrupted version.
NTFS also includes a self-healing feature, which works to prevent bad sector errors within the file system. This self-healing feature does not require the volume to be taken offline, which is crucial, as downtime can be incredibly disruptive to a client’s operations [https://www.solarwindsmsp.com/blog/how-sell-backup-3-easy-steps]. Should a data cluster become corrupted or damaged, it efficiently removes the affected cluster and reassigns the information to a new one. Essentially, this means the NTFS file structure actively works to identify malfunctioning or damaged clusters on the disk and creates workarounds that won’t impede your ability to access the disk drive.
ReFS structures are designed to be highly compatible with NTFS and also include a number of features to ensure reliable and secure data storage. ReFS is notable for its use of checksums for both metadata and file data. Similar to the way end-to-end encryption ensures you’re communicating with the correct recipient, ReFS uses checksums when reading and writing files to confirm that each file is the correct one. These checksums allow for the file structure to monitor data distortion in real time. While NTFS requires the implementation of the manual “check disk” function, the design of ReFS has automated this process.
Another notable feature of ReFS is the “copy-on-write” function. NTFS edits a file’s metadata directly, which risks data damage or loss in the event of a power or operating system failure. In contrast, ReFS creates a copy when editing the metadata, and only links the data to its corresponding file after the metadata has been written to the disk. This helps to prevent data loss even if a power or system failure were to occur.
ReFS also includes a data integrity scanner, or scrubber, which scans the entire system to identify and repair corrupted data. When integrated with Storage Spaces, ReFS offers a variety of intelligent and intuitive behind-the-scenes features. For instance, the automatic repair feature keeps your systems online while repairs take place. And unlike NTFS, ReFS automatically removes any damaged data it detects without the need to restart the system. If you happen to be using a mirrored data storage, the ReFS structure works to identify system errors and fixes any issues it encounters by using the alternative copy of the data from the other storage site. This also has the added benefit of protecting data from partial or complete disk failures by storing copies of the data across multiple disks.
Beginning with Windows Server 2008, Microsoft introduced Transactional NTFS, which enhances file operations performance. It also provides an added level of security through transactions, which make multiple changes to files across a system. Transactions are designed to be all or nothing: either all of the operations are written to disk or none of them are. In the event of a system failure, operations that have been completed are written to disk and incomplete transactions are not, instead reverting back to a previously logged state. This works to maintain data security while allowing you to continue normal file operations uninterrupted.
Other key features of NTFS that help increase performance include disk quotas, file compression, and resizing. By setting caps for the disk space that users have access to, administrators can keep track of how the various drives and servers are operating by identifying when the limits have been exceeded. File compression and resizing work in tandem: NTFS can increase the storage capacity of a drive by using an algorithm to compress the system files, and resizing allows you to adjust the NTFS partition by tapping into unallocated disk space. Other NTFS-only functions include an encrypting file system, hard links, and extended attributes.
ReFS was designed to provide a better file performance system, and one advantage of ReFS over NTFS is mirror-accelerated parity [https://docs.microsoft.com/en-us/windows-server/storage/refs/mirror-accelerated-parity]. This process allocates data across two different tiers on a drive, optimizing each for high performance and efficient data storage. The mirror tier runs in performance mode, greatly accelerating file read and write times, but also using up a greater amount of disk space. The parity tier has to recompute with every file written, but makes more efficient use of disk space. By actively moving data between the mirror and parity tiers in real time, ReFS achieves the best of both worlds: writing to disk quickly in the mirror tier and then shifting the data into parity for efficient storage.
There are also two primary ways in which ReFS provides better performance and functionality for virtual machines. One is through the support of block cloning. This means multiple files can link to the same basic data on the disk drive, allowing you to quickly create multiple copies of a virtual machine without using up a similar amount of space on the disk. The other is through Sparse valid data length (VDL), which uses zero-filling files to reduce the time it takes to create a virtual hard disk to mere seconds.
As mentioned, the ReFS file structure was designed to efficiently handle massive amounts of data. In fact, according to Microsoft, ReFS can support data sets up to millions and millions of terabytes in size—the only restriction really being the limits of your hardware. This is far more than what NTFS is able to support, making ReFS a good option for customers looking to quickly scale.
Despite this advantage, the bottom line is that neither NTFS or ReFS is the inherently better file structure. There are advantages to each, which means it’s critical that you understand your customer’s systems and needs when helping guide them through NTFS or ReFS drive partitions.
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