[Sony Xperia L] jayaura:
I'm on Thunderzap kernel 3.0, with CWM 6.0.3.5. Whenever I try to make a backup to external sd, or try to mount ext sd card, cwm says its cant mount external sd. I have done this earlier on old ROMs. Currently on 15.3.A.0.26, (android 4.2.2). Phone is rooted, BL unlocked.

Given below is the recovery.log after trying to access "Backup to External sd" and "Mount external sd".

I think the primary reason for failure is log claiming that the filesystem on sd card is non-vfat. However, the sd card was formatted by android itself. So it must be must be fat32, and yes, it is - I mean, I didnt touch the card's partition or format it outside the phone.

Weird thing is that Gparted shown my 32 GB Sandisk Ultra (Class 10) card as Unallocated space (while it was mounted). Yet the phone mounts the card in mass storage mode and I can read/write.

Starting recovery on Tue Feb 24 21:54:23 1970
Successfuly set bpp vi to 32
framebuffer: fd 4 (480 x 854)
CWM-based Recovery v6.0.3.5(Powered by TZ)
recovery filesystem table
=========================
0 /tmp ramdisk (null) (null) 0
1 /boot emmc /dev/block/platform/msm_sdcc.1/by-name/boot (null) 0
2 /system ext4 /dev/block/mmcblk0p28 (null) 0
3 /cache ext4 /dev/block/mmcblk0p30 (null) 0
4 /data ext4 /dev/block/mmcblk0p31 (null) -16384
5 /sdcard vfat /dev/block/mmcblk0p32 (null) 0
6 /external_sd auto /dev/block/mmcblk1p1 /dev/block/mmcblk1 0

W:Unable to get recovery.fstab info for /datadata during fstab generation!
W:Unable to get recovery.fstab info for /emmc during fstab generation!
W:Unable to get recovery.fstab info for /sd-ext during fstab generation!
I:Completed outputting fstab.
I:Processing arguments.
I:Checking arguments.
I:device_recovery_start()
Command: "/sbin/recovery"

ro.boot.hardware=qcom
ro.boot.emmc=true
ro.boot.bootloader=s1
ro.boot.serialno=ZH80004JV8
ro.boot.baseband=msm
ro.serialno=ZH80004JV8
ro.bootmode=unknown
ro.baseband=msm
ro.bootloader=s1
ro.hardware=qcom
ro.revision=0
ro.emmc=0
ro.factorytest=0
ro.secure=0
ro.allow.mock.location=1
ro.debuggable=1
persist.sys.usb.config=adb
ro.build.id=JSS15J
ro.build.display.id=cm_taoshan-eng 4.3 JSS15J eng.varun.chitre15.20130801.154858 test-keys
ro.build.version.incremental=eng.varun.chitre15.20130801.154858
ro.build.version.sdk=18
ro.build.version.codename=REL
ro.build.version.release=4.3
ro.build.date=Thu Aug 1 15:49:28 BST 2013
ro.build.date.utc=0
ro.build.type=eng
ro.build.user=varun.chitre15
ro.build.host=build1
ro.build.tags=test-keys
ro.product.model=taoshan
ro.product.brand=sony
ro.product.name=cm_taoshan
ro.product.device=taoshan
ro.product.board=taoshan
ro.product.cpu.abi=armeabi-v7a
ro.product.cpu.abi2=armeabi
ro.product.manufacturer=sony
ro.product.locale.language=en
ro.product.locale.region=US
ro.wifi.channels=
ro.board.platform=unknown
ro.build.product=taoshan
ro.build.description=cm_taoshan-eng 4.3 JSS15J eng.varun.chitre15.20130801.154858 test-keys
ro.build.fingerprint=sony/cm_taoshan/taoshan:4.3/JSS15J/eng.varun.chitre15.20130801.154858:eng/test-keys
ro.build.characteristics=default
ro.cm.device=taoshan
ro.rommanager.developerid=cyanogenmod
keyguard.no_require_sim=true
ro.url.legal=http://www.google.com/intl/%s/mobile/android/basic/phone-legal.html
ro.url.legal.android_privacy=http://www.google.com/intl/%s/mobile/android/basic/privacy.html
ro.com.google.clientidbase=android-google
ro.com.android.wifi-watchlist=GoogleGuest
ro.setupwizard.enterprise_mode=1
ro.com.android.dateformat=MM-dd-yyyy
ro.com.android.dataroaming=false
ro.cm.version=10.2-20130801-UNOFFICIAL-taoshan
ro.modversion=10.2-20130801-UNOFFICIAL-taoshan
ro.config.ringtone=Orion.ogg
ro.config.notification_sound=Argon.ogg
ro.config.alarm_alert=Hassium.ogg
ro.carrier=unknown
ro.ril.hsxpa=1
ro.ril.gprsclass=10
ro.adb.qemud=1
ro.kernel.android.checkjni=1
net.bt.name=Android
net.change=net.bt.name
dalvik.vm.stack-trace-file=/data/anr/traces.txt
init.svc.ueventd=running
init.svc.adbd=running
init.svc.recovery=running

I:Checking for extendedcommand...
I:Skipping execution of extendedcommand, file not found...
mount: mounting /dev/block/mmcblk1p1 on /external_sd failed: No such file or directory
Can't mount backup path.
mount: mounting /dev/block/mmcblk1p1 on /external_sd failed: No such file or directory
Error mounting /external_sd!
I:Can't partition non-vfat: auto
I:Can't format unknown volume: /emmc