Hi guys,
I faced a problem with my 64gb. Sandisk micro SD and I solved the issue and I thought about posting the solution here that might help some of you.
so… the issue I faced is how to get TWRP recovery or CWM to mount my Ex sd card.
basically the problem is that the card is formatted in exfat or NTFS and in both ways it won’t be recognized by TWRP and the only way to formate it in fat32 is by only one software because windows can not format more than 32gb in Fat32.
and here is how:

first: download EaseUS Partition Master Home Edition from this link http://download.cnet.com/EaseUS-Part…dlPid=10982635

Second : Now you can see a list of all of your hard drives. Note the one highlighted in blue on the grid. This is my 64GB MicroSDXC card in my USB Card Reader. Obviously the location of your card in the list may differ dependant on the number of drives in your computer

You’ll need to right-click on the drive in the list representing your 64GB MicroSDXC card and click “Format partition”

Third : You need to select FAT32 for the File System, and 32KB for Cluster Size.
EaseUS doesn’t immediately apply the changes you specify. Instead, it queues them up so that you can review and revise them before you commit to having the program affect those changes. then we need to press the Apply button.

that’s it … now you can enjoy your 64gb MicroSd and you can mount it in TWRP or CWM recovery .

https://forum.xda-developers.com/galaxy-s3/general/how-to-format-64gb-micro-sd-card-to-t2041679

 

Default cluster size for NTFS, FAT, and exFAT

Applies to: Windows 10 Pro released in July 2015Microsoft Windows Server 2003 Datacenter Edition (32-bit x86)Microsoft Windows Server 2003 Enterprise Edition (32-bit x86) More

Summary


All file systems that are used by Windows organize your hard disk based on cluster size (also known as allocation unit size). Cluster size represents the smallest amount of disk space that can be used to hold a file. When file sizes do not come out to an even multiple of the cluster size, additional space must be used to hold the file (up to the next multiple of the cluster size). On the typical hard disk partition, the average amount of space that is lost in this manner can be calculated by using the equation (cluster size)/2 * (number of files).

If no cluster size is specified when you format a partition, defaults are selected based on the size of the partition. These defaults are selected to reduce the space that is lost and to reduce the fragmentation that occurs on the partition.

More Information


A hard disk partition (also known as a volume) can be formatted to NTFS, FAT, or exFAT. The default values are used by Windows when one of the following methods is used to format the partition:

  • Using the FORMAT command from the command line without specifying a cluster size.
  • Formatting a volume from Windows Explorer when the Allocation Unit box in the Format dialog box lists Default Allocation Size.

By default, the maximum cluster size for NTFS under Windows NT 4.0 and later versions of Windows is 4 kilobytes (KB). This is because NTFS file compression is not possible on drives that have a larger cluster size. The format command won’t use clusters larger than 4 KB unless the user specifically overrides the default settings. You can do this by using the /A: switch together with the Format command or by specifying a larger cluster size in the Format dialog box in Windows Explorer.

When you use the Convert.exe utility to convert a FAT partition to NTFS, Windows always uses the original FAT cluster size as the NTFS cluster size for cluster sizes up to 4 KB. If the FAT cluster size is greater than 4 KB, then the clusters are converted down to 4 KB in NTFS. This is because the FAT structures are aligned on cluster boundaries. Therefore, any larger cluster size would not allow for the conversion to function. Note also when formatting a partition under Windows NT 3.5, 3.51, and 4.0 Setup, the partition is first formatted to FAT and then converted to NTFS, so the cluster size will also always be as described earlier when a partition is formatted in Setup.

Default cluster sizes for NTFS

The following table describes the default cluster sizes for NTFS.

Volume size Windows NT 3.51 Windows NT 4.0 Windows 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista, Windows Server 2003, Windows XP, Windows 2000
7 MB–512 MB 512 bytes 4 KB 4 KB
512 MB–1 GB 1 KB 4 KB 4 KB
1 GB–2 GB 2 KB 4 KB 4 KB
2 GB–2 TB 4 KB 4 KB 4 KB
2 TB–16 TB Not Supported* Not Supported* 4 KB
16TB–32 TB Not Supported* Not Supported* 8 KB
32TB–64 TB Not Supported* Not Supported* 16 KB
64TB–128 TB Not Supported* Not Supported* 32 KB
128TB–256 TB Not Supported* Not Supported* 64 KB
> 256 TB Not Supported Not Supported Not Supported

Note The asterisk (*) means that it is not supported because of the limitations of the master boot record (MBR).

Default cluster sizes for FAT16

The following table describes the default cluster sizes for FAT16.

Volume size Windows NT 3.51 Windows NT 4.0 Windows 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista, Windows Server 2003, Windows XP, Windows 2000
7 MB–8 MB Not supported Not supported Not supported
8 MB–32 MB 512 bytes 512 bytes 512 bytes
32 MB–64 MB 1 KB 1 KB 1 KB
64 MB–128 MB 2 KB 2 KB 2 KB
128 MB–256 MB 4 KB 4 KB 4 KB
256 MB–512 MB 8 KB 8 KB 8 KB
512 MB–1 GB 16 KB 16 KB 16 KB
1 GB–2 GB 32 KB 32 KB 32 KB
2 GB–4 GB 64 KB 64 KB 64 KB
4 GB–8 GB Not supported 128 KB* Not supported
8 GB–16 GB Not supported 256 KB* Not supported
> 16 GB Not supported Not supported Not supported

Note The asterisk (*) means that it is available only on media with a sector size greater than 512 bytes.

Default cluster sizes for FAT32

The following table describes the default cluster sizes for FAT32.

Volume size Windows NT 3.51 Windows NT 4.0 Windows 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista, Windows Server 2003, Windows XP, Windows 2000
7 MB–16MB Not supported Not supported Not supported
16 MB–32 MB 512 bytes 512 bytes Not supported
32 MB–64 MB 512 bytes 512 bytes 512 bytes
64 MB–128 MB 1 KB 1 KB 1 KB
128 MB–256 MB 2 KB 2 KB 2 KB
256 MB–8GB 4 KB 4 KB 4 KB
8GB–16GB 8 KB 8 KB 8 KB
16GB–32GB 16 KB 16 KB 16 KB
32GB–2TB 32 KB Not supported Not supported
> 2TB Not supported Not supported Not supported

Default cluster sizes for exFAT

The following table describes the default cluster sizes for exFAT.

Volume size Windows 7, Windows Server 2008 R2, Windows Server 2008, Windows Vista, Windows Server 2003, Windows XP
7 MB–256 MB 4 KB
256 MB–32 GB 32 KB
32 GB–256 TB 128 KB
> 256 TB Not supported

Last Updated: 17 Apr 2018