A: The table below summarizes the main features that are supported on NTFS but not on the Windows Server 2012 ReFS file system.
NTFS should still be used for most scenarios and will be around for a long time. ReFS is a specialized file system for specific purposes today that handles a subset of what NTFS does, without having all the overhead that NTFS has. Note that ReFS supports Cluster Shared Volumes and BitLocker, so it's not on this list.
| Functionality | NTFS | ReFS |
| Named Streams | Yes | No |
| OBJECT IDs | Yes | No |
| File System Compression | Yes | No |
| File System Encryption | Yes | No |
| TRANSACTIONS | Yes | No |
| Sparse Files | Yes | No |
| Hard Links | Yes | No |
| Extended Attributes | Yes | No |
| Quota | Yes | No |
| Max size of a single file | (264-1) bytes | (264-1) bytes |
| Max size of a single volume | Roughly 256 TB | Roughly 4.7 ZB (zettabytes) |
| Max number of files in a directory | No actual limitation | 2^64 |
| Max number of directories in a volume | No actual limitation | 2^64 |
| Max file name length | 32K unicode characters | 32K unicode characters |
| Max path length | 32K | 32K |
| Boot to file system | Yes | No |
| Supported on removable media | Yes | No |
| Deduplication | Yes | No |
| WDS | Yes | No |
Note also that ReFS only uses a 64KB cluster size, which means a lot of wasted space for disks with lots of small files. Since ReFS uses a Copy on Write mechanism, there's a greater chance of fragmentation.
