Resilient File System

Ayush Gupta

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ContentsIntroduction Features of ReFSAttributes of ReFSHow ReFS works??Improvements in NTFSDifference between ReFS and NTFSSymptoms of ReFS FailureScalability of ReFSPetabytes of Storage in ReFS.Pros and Cons of ReFSSummary

IntroductionReFS is acronym for Resilient File System developed by Microsoft for Windows 8 Servers in advancement to the NTFS.

ReFS has inherited some features from NTFS and has ignored some like Hardlink, Quotas, File Compression etc.

ReFS provides high data availability and prevents data from being corrupted. ReFS supports high volume of storage.

ReFS provides resiliency to the data due to which data never gets corrupted.

ReFS never takes the File System Offline.

In Windows 8, ReFS will be introduced only as part of Windows Server 8, which is the same approach we have used for each and every file system.

ReFS uses B+ file system structure.

FEATURESIntegrityAvailabilityScalabilityProactive Error IdentificationBuild In ResilienceReliabilityData StrippingCompatibility

A TTRIBUTESMaximum Size of Single File: 2^64-1 bytes  Maximum no. of files in directory: 2^64 Maximum File Name Length: 32K 255 Unicode characters  Maximum Path Length: 32K Maximum Storage Space: 4PB 

How ReFS Works???Data Storage Integrity is maintained through “Data Verification and AutoCorrection” Of File System.

CHKDSK is not applicable in ReFS as auto correction of corrupted data is done.

• The main improvement from NTFS to ReFS is that the time required for CHKDSK on corrupted volume is greatly reduced.

• Windows Server 8 takes negligible time as compared to Windows Server 2008.

NTFS IMPROVEMENTS

NTFS vs ReFS Functionality NTFS ReFS

De Duplication Yes No

Named Streams Yes No

Object Ids Yes No

File System Compression Yes No

File Encryption Yes No

Sparse Files Yes No

Hard Links Yes No

Quotas Yes No

Maximum Size of Single File (264-1) bytes (264-1) bytes

Maximum Size of Single Volume Roughly 256 TB Roughly 4.7 ZB (zettabytes)

Support on Removable Media Yes No

Maximum Path Length 32K 32K

Boot to file system Yes No

WDS Yes No

Symptoms of ReFS Failure Although ReFS is made to resist failures, it itself can also fail.

During ReFS failure, OS can’t access ReFS volume and error message is displayed.

ReFS can’t be recovered…….Only Data Recovery is done.

Scalability of ReFSAs the amount and size of information that's stored on

computers continues to speedily increase, ReFS is meant to work well with very massive information sets, petabytes and bigger.

The ReFS on-disk format is intended to support volume sizes up to 2^78 bytes using 16KB cluster sizes whereas the Windows stack addresses permits 2^64 bytes.

This format also supports 2^64-1 byte file sizes, 2^64 files during a directory, and also the same range of directories during a volume.

Petabytes of Storage in ReFS Storage Volume are used in combination with ReFS to increase the storage space .

Collection of physical drives is called Just a Bunch of Drives

Just a Bunch of Drives(JBOD) with Serial ATA and SCSI is used to store petabytes.

Storage Spaces also supports common fault tolerance like data Stripping, Mirroring and Stripping with parity.

PROS AND CONS

Pros CheckSum Metadata ConsistencyAutoRepairResilienceScalabilityIntegrity

ConsNo Recovery tool for ReFSNo File Compression.No DeDuplicationNo HardlinksNo QuotasNo File Conversion Support

SUMMARYReFS is a future of file system. It provides many features like integrity, protection against data loss, scalability etc.

But if few modifications are made in it, it can be made better.

Being a new file system, it must support all the features of old file system like NTFS.

THANK YOU