I want purchase a new high capacity (64GB or 128GB) high speed (100Mbps 170Mbps 250 MBps) MicroSdcard for Swapping/Adoptable /linking apps through Link2SD/ portable (adoptable) storage

so i want to confirm compatibility feasibility speed performance my external sdcard slot/tray/reader/chip/hardware should have according to my device and Android lolipop 5.1.1 support.

High capacity MicroSd card comes with pre-formatted extfat file system but my mobile manufacturer technical specification of mobile device says it supports up to 128gb and fat32 file system

There are many available sdcards Micro i want to know that type (SDHC SDXC) UHs speed Class (UHSI UHS II) Video Speed Class (v10 v30 v60 V90) and App performance class (A10) Speed of (90 Mbps 100Mbps 170Mbps 250MBps) its confusing which will be compatible feasible and best for adaptable swap and give optimum performance for the purpose.

secondly there is not use of extra speed or video class card if Device or Android supports works on less speed.

Before purchasing to decide i want to confirm and check my device and understand clarify following questions and queries to decide which card will be compatible for my android lolipop 5.1.1 OS and device:-

  1. Can high capacity exfat be forced to used (through mounting it inboot init) in android or phone through mount commands without damaging phone Android os or SDcards protocols and will all apps/ os file manager support it if yes then

                                  *-kindly tell me commands for it.*
  2. if not then can high capacity card be formatted to Fat32 if yes then how can i format and will the card give the same performance speed performance as in exfat to fat32 without damaging phone android OS and SdCard

                                     *-kindly tell me commands for it*
  3. In android Lolipop 5.1.1 file system (ext4) whats the block size it use to write or read on external sdcard is it 512 bytes/ 4096 (4kB) /8096 (8KB) /512Kb /512bytes how to check or it depends on which filesystem the sdcard is formatted with then what block size it writes individualy in filesystems of fat32, exfat, ntfs and ext4

    • kindly tell me command tools script or apps to check and confirm on my device
  4. In android lolipop 5.1.1 file system of ext4 APPS and FILES how it write means sequentially or randomly

             -kindly tell me command tools script or apps  to check and 
              confirm on my device
  5. is there method or any adb shell android Command or script or apps of hardware info or bench marking apps through which we can check test to know device mobiles external Sdcard *SLOTS/READER/CHIP/HARDWARE** optimum hardware compatibility :-

    a) for type of device compatible microSD cards (SDHC / SDXC)

                     *- kindly tell me commands for testing it* 

    b) Type of file system supported or mounted OR FORCED TO BE MOUNTED allowed/permitted on externalsd card and can it be modified or changed

                              *- kindly tell me commands for testing it* 

    c) maximum Practical capacity supported microSD in the device and can it be forcebly be extended ie. 128gb or more we can force by partitioning the card to multiple partitions or increasing the size

                              *- kindly tell me commands for testing it* 

    d) UHS speed Class (UHSI UHS II) compatible

                             *- kindly tell me commands for testing it* 

    e) Video Speed Class (v10 v30 v60 V90) compatible

                             *- kindly tell me commands for testing it* 

    f) App performance class (A1) compatible

                             *- kindly tell me commands for testing it* 

    g) Maximum sequential read speed compatible (90 Mbps 100Mbps 170Mbps 250MBps)

                             *- kindly tell me commands for testing it* 

    h) minimum/Maximum sequential write speed compatible

                             *- kindly tell me commands for testing it* 

    i) minimum/ Maximum random read/write speed compatible - kindly tell me commands for testing it

  6. for suggestions I have pre-tested through androbench app

    a) internal memory of my device through writing 64Mb file to /data/ (ext4 partition mounted) (64Mb file used for testing)

    sequential  read 128 MB/s
    sequential write 12 MB/s
    random read 10.93 Mb/s  2800.4 IOPS (4KB)
    random write 3.9 Mb p/s  996.31 IOPS (4KB)

    is there any restriction in device or android should we need to match
    externalsd speed performance with internal sd as we have we can use
    external sdcard as internal either by swapping/adoptable /linking or it will work in more or less performance to

    b) External memory of HP SHDHC Class 10 16GB (still i want to switch over to high capacity card) of my device through writing 64Mb file /external_sd/ (fat32 partition mounted)(64 MB File)

    sequential  read 35.56 MB/s (printed 95MB/s)
    sequential write 8.6 MB/s
    random read 4.36 Mb/s  1117.58 IOPS (4KB)
    random write 0.53 Mb p/s  136.38 IOPS (4KB)

    Hp printed 95MB/s but result is 35.5MB/s now its device result,fat32 file system result or sdcard performance result don't know how to
    differentiate it .

                        *- kindly tell me commands for testing it* 

how to find device external mircro sdcard slot/chip/hardware/reader speed and other information asked above

1 Answer 1


Your device is very old, which most likely means that it does not have exfat support.

Compatibility should not be a problem, as every card and reader are usually compatible with each other, as long as SDXC cards are supported by your device.

And for adoptable storage the bulk transfer speed is not that important (as long as you don't record videos or often copy/download large files). I would focus on A1/A2 rating which is designed to measure application usage (randomly reading/writing a number of small files).

I would also focus on reliability because if the sd-card dies all data on your device will be non-accessible/gone.

Anyway in your old device the sd-card will not work very fast. Even in modern devices the sd-card reader is not able to make use of the modern very fast transfer modes.

In general the micro-sd card is way slower (independent what card you use) than the internal flash, because the integrated card reader is slow.

  • in brief how can we check test and see the integrated card reader specification of the devices through any app benchmarking tool or any command Commented Jan 4, 2020 at 15:24
  • how can we precheck reliability of Externalsd card. and integrated card reader Commented Jan 4, 2020 at 15:28
  • @Androidquery SD-card reader capabilities: read the technical specification of the phone and if you don't find there something on the reader you can't (only guess it from the transfer speed you measure). Anyway just assume the worst so you don't get disappointed. Also the reliability can't be really checked. Buy branded product of a brand that also produces flash memory (like e.g. SanDisk, Samsung, ..). And make sure to check if you did not bought a forged product (test the disk using h2testw or a similar tool if it really has the claimed capacity).
    – Robert
    Commented Jan 4, 2020 at 15:35
  • robert as a2 feature is available with UHSII or UHSIII cards integrated reader detect (on low speed low performance ) or not because they are expensive and if dosnt get detected even then it will be wastage on old phones as some site i readed that it needs some special voltage of 3.99 thats what i want to know that if purchase some card and later on it didnt detetcted then it will be problem Commented Jan 4, 2020 at 15:49
  • currently no known UHS-II smartphones or tablets. the Galaxy S10 is UHS-I only. you are fine with any Class 10 SDXC
    – alecxs
    Commented Jan 4, 2020 at 21:02

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