Quote
axl79
Good point about the NTFS, if you use the old FAT32 file system it will limit you to max 2GB long files, which it's a problem when you want to store iso files from DVDs, susally bigger tha 2 Gbytes.
Yes axl, you are right, but I was meaning about safety (integrity of data, no loss) in NTFS, all this features below are NOT present on Fat (taken from
[
technet.microsoft.com]
NTFS Change JournalAs files, folders, and other NTFS objects are added, deleted, and modified, NTFS enters change journal records in streams, one for each volume on the computer.
The total size of all the records currently in the journal varies, but there is a configurable maximum size. The change journal can exceed the maximum size until the size reaches an outer threshold, at which point a portion of the oldest records are deleted until the change journal is restored to its maximum size. The maximum size of the change journal is configurable but cannot be reduced, only increased.
The change journal conveys significant scalability benefits to applications that might otherwise need to scan an entire volume for changes. File system indexing, replication managers, virus scanners, and incremental backup applications can benefit from using the change journal.
The change journal is much more efficient than time stamps or file notifications for determining changes in a particular namespace. Applications that must rescan an entire volume to determine changes can now scan once and subsequently refer to the change journal. The I/O cost depends on how many files have changed, not on how many files exist on the volume.
The APIs are fully documented and can be leveraged by independent software vendors (ISVs). Microsoft uses the change journal in Windows Server 2003 components such as the Indexing Service and File Replication Service. ISVs can use this feature to enhance the scalability and robustness of a range of products including backup, antivirus, and auditing tools.
NTFS File System RecoverabilityNTFS is a recoverable file system that guarantees the consistency of the volume by using standard transaction logging and recovery techniques. In the event of a system failure, NTFS runs a recovery procedure that accesses information stored in a transaction log file. The NTFS recovery procedure guarantees that the volume is restored to a consistent state. Transaction logging requires very little overhead.
Recovering NTFS File StructuresNTFS views each operation that modifies a file on a volume as a transaction and manages each one as an integral unit. NTFS might also break a single complex operation into multiple transactions. After a transaction is started, it is either completed, or if an event occurs that causes the operation to fail, it is rolled back, and the NTFS volume returns to its state before the transaction began. Events that can cause an operation to fail include bad sectors, transient low-memory conditions, and disconnected devices.
To ensure that a transaction can either be completed or rolled back, NTFS performs the following steps for each transaction:
Records the metadata operations of a transaction in a log file cached in memory.
Records the actual metadata operations in memory.
Marks the transaction in the cached log file as committed.
Flushes the log file to disk.
Flushes the actual metadata operations to disk.
Steps 4 and 5 occur in a lazy fashion after the transaction is completed, meaning that the flush operations are not tied to the transaction itself. Instead, NTFS modifies the log and metadata quickly in memory, and then flushes later at a convenient time to boost performance.
NTFS guarantees that the log records containing the metadata operations of the transaction are written to disk before the metadata that is modified in the transaction is written to disk. After NTFS updates the cache, NTFS commits the transaction by recording in the cached log file that the transaction is complete. After the cached log file is flushed to disk, all committed transactions are guaranteed to be completed, even if the system fails before the changes are written to disk.
Note
Applications can specify the FILE_FLAG_WRITE_THROUGH Win32 flag to instruct the system to write through any intermediate cache and go directly to disk. The system can still cache write operations, but cannot lazily flush them.
If a system failure occurs, NTFS has enough information in the log to complete or abort any partial NTFS transaction. During recovery operations, NTFS redoes each committed transaction found in the log file. Then NTFS locates in the log file the transactions that were not committed at the time of the system failure and undoes each metadata operation recorded in the log file. Because NTFS flushes the log to disk before any metadata changes are written to disk, NTFS has complete information available about any metadata changes that need to be rolled back during recovery.
Note
NTFS uses transaction logging and recovery to guarantee that the volume structure is not corrupted. For this reason, all file system data is accessible after a system failure. NTFS guarantees user data only if the program used to create the data uses the FILE_FLAG_WRITE_THROUGH Win32 flag. If the program does not use this flag, user data can be lost due to a system failure. If a system failure does occur, NTFS shows either the previous data, the new data, or zeros. Users do not see random data on the volume as the result of a crash.