usb sd card reader that will recognize Linux partitions

the card reader have nothing to do with the format of card. try with another card reader and kindly post the reply. also check "disk monitor" whether its recognizing it or not.

sd cards use the vfat format, not ext2.
and as murali said, card readers and the format of sd cards have nothing to do with each other.

Like most media, SD cards can be formatted for different types of partitions. ext2 on SD cards is quite common in embedded Linux environments. I'm using Ubuntu as a development platform targeting an embedded Linux system, which can boot from an SD card formatted with an ext2 partition. I have a proven good ext2 SD card from which the embedded system boots just fine. However, I would also like to access the card directly on my Ubuntu system.

Further, I have a USB SD card reader that works fine with SD cards with certain types of partitions such as vfat. However, it does not recognize the known good SD card with the ext2 partition. I also have colleagues that access ext2 partitions on SD cards from essentially the same Ubuntu development environment using built-in (to their laptops or monitors) SD card readers. As I don't have access to a built-in SD card reader, I would like to get a USB SD card reader that can work with SD cards with ext2 partitions.

problem may be likely with the card reader. try with another card reader of
a different brand.

Yes, this is the point from which I started. My original inquiry was for recommend brands.

The SD card reader know nothing about file system. For it, media is only an array ob blocks of 512B.
Under which OS run the PC with card reader ?
Is it able to read SD card with FAT32 on the same USB plug ?

I've used the SD card reader with Window 7 and with Ubuntu 9.10, 10.4, and 11.10. In all cases FAT32 can be read and in all cases ext2 cannot be recognized. I understand that Window 7 may not be able to recognize ext2 but certainly Linux can.

Could you provide result of command:
   ls /media
and
   sudo fdisk -l

Before card reader is plugged in:

developer@developer-desktop:~$ ls /media
cdrom cdrom0 nnts_opt

developer@developer-desktop:~$ sudo fdisk -l
[sudo] password for developer:

Disk /dev/sda: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000f0c24

   Device Boot Start End Blocks Id System
/dev/sda1 * 1 1995 16024806 83 Linux
/dev/sda2 1996 2088 747022+ 5 Extended
/dev/sda5 1996 2088 746991 82 Linux swap / Solaris

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000074c6

   Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 83 Linux

--------------------------------------------------------------------------

After plugging in SD card reader with ext2 partitioned SD card:

developer@developer-desktop:~$ ls /media
cdrom cdrom0 nnts_opt

developer@developer-desktop:~$ sudo fdisk -l

Disk /dev/sda: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000f0c24

   Device Boot Start End Blocks Id System
/dev/sda1 * 1 1995 16024806 83 Linux
/dev/sda2 1996 2088 747022+ 5 Extended
/dev/sda5 1996 2088 746991 82 Linux swap / Solaris

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000074c6

   Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 83 Linux

Unable to read /dev/sdc

--------------------------------------------------------------------------

After plugging in the SD card reader with another SD card with a partition of a different format

developer@developer-desktop:~$ ls /media
1BA2-A505 cdrom cdrom0 nnts_opt

developer@developer-desktop:~$ sudo fdisk -l
[sudo] password for developer:

Disk /dev/sda: 17.2 GB, 17179869184 bytes
255 heads, 63 sectors/track, 2088 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000f0c24

   Device Boot Start End Blocks Id System
/dev/sda1 * 1 1995 16024806 83 Linux
/dev/sda2 1996 2088 747022+ 5 Extended
/dev/sda5 1996 2088 746991 82 Linux swap / Solaris

Disk /dev/sdb: 21.5 GB, 21474836480 bytes
255 heads, 63 sectors/track, 2610 cylinders
Units = cylinders of 16065 * 512 = 8225280 bytes
Disk identifier: 0x000074c6

   Device Boot Start End Blocks Id System
/dev/sdb1 1 2610 20964793+ 83 Linux

Disk /dev/sdc: 1967 MB, 1967128576 bytes
57 heads, 56 sectors/track, 1203 cylinders
Units = cylinders of 3192 * 512 = 1634304 bytes
Disk identifier: 0x00000000

   Device Boot Start End Blocks Id System
/dev/sdc1 1 1204 1920955+ 6 FAT16

The problem doesn't lie in file system. The key is not properly recognized.
Could you try command lsusb which lists devices detected (even if not mounted) on the bus.
Could you connect on other USB port of computer
Could you try this USB stick on another computers

Before the card reader is plugged in

developer@developer-desktop:~$ lsusb
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

----------------------------------------------------------------------------------

After the card read is plugged in with no SD card inserted

developer@developer-desktop:~$ lsusb
Bus 001 Device 006: ID 058f:6332 Alcor Micro Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

----------------------------------------------------------------------------------

After the card read is plugged in with the ext2 SD card inserted

developer@developer-desktop:~$ lsusb
Bus 001 Device 006: ID 058f:6332 Alcor Micro Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

----------------------------------------------------------------------------------

After the card read is plugged in with the FAT16 SD card inserted

developer@developer-desktop:~$ lsusb
Bus 001 Device 007: ID 058f:6332 Alcor Micro Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

----------------------------------------------------------------------------------

After the card read is plugged into a different USB port

developer@developer-desktop:~$ lsusb
Bus 001 Device 007: ID 058f:6332 Alcor Micro Corp.
Bus 001 Device 001: ID 1d6b:0002 Linux Foundation 2.0 root hub
Bus 002 Device 002: ID 0e0f:0002 VMware, Inc. Virtual USB Hub
Bus 002 Device 001: ID 1d6b:0001 Linux Foundation 1.1 root hub

-----------------------------------------------------------------------------------

I have tried three different versions of Ubuntu across two different physical computers as well as different USB ports on those systems. In all cases I get the same results.

OK, I'm going to answer my own question. I just acquired and tested an IOGEAR 50-in-1 Portable Card Reader / Writer. It worked just fine with the ext2 formatted SD card. While I can't say definitively that the issue is related to the model, I certainly can say that it's related to the specific card readers. Either my original model doesn't handle ext2 formatted SD cards or it was just defective (although it's strange that it could handle the more common Windows and consumer product formats just fine).

So I'm going to say the answer to my original question is - IOGEAR 50-in-1 Portable Card Reader / Writer. I'll also be testing a unit from Tribeca (that I haven't received yet), which I've been told by a colleague will also work.