I am using a Kingston MMC USB reader with a Samsung 64Gb microSDXC UHS-I card. The first time I inserted it, this dialog appeared:
So I searched around and found a similar q/a here; I performed the steps in the answer for the question: Unable to access 64gb volume – Ubuntu 14.04
Now the error dialog does not appear any longer, but the 64Gb card only mounts as 29Gb volume now.
Here is the output of lsusb if that helps:
Bus 003 Device 006: ID 090c:6000 Silicon Motion, Inc. - Taiwan (formerly Feiya Technology Corp.) SD/SDHC Card Reader (SG365 / FlexiDrive XC+)
fdisk output:
Disk /dev/sdd: 28.5 GB, 28521267200 bytes 255 heads, 63 sectors/track, 3467 cylinders, total 55705600 sectors Units = sectors of 1 * 512 = 512 bytes Sector size (logical/physical): 512 bytes / 512 bytes I/O size (minimum/optimal): 512 bytes / 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sdd1 32768 122814463 61390848 7 HPFS/NTFS/exFAT
Best Answer
That's unusual. Did the card work on windows with the same card reader, and writing more than 32GB worked ok?
Any changes with a different card reader, in Ubuntu or windows?
There are lots of differing card readers of varying quality, some slower, some unreliable, some can't handle SDHC or SDXC (like this one) even though they may advertise they can.