Compact Flash card testing

[Aleksandar Aleksiev]

Hi guys,

I would like to present one interesting and not well explained so far Compact Flash (CF) question here and to have it as a future reference for anybody in similar situation.

A 128M CF - booting without problems	8G CF formated with FAT32 - no boot possible	8G CF with FAT16 - should boot normally
C3825ISR#sh flash: filesys ******** ATA Flash Card Geometry/Format Info ******** ATA CARD GEOMETRY    Manufacturer Name    Model Number           TOSHIBA THNCF128MBA    Serial Number          STCB21M82017D98691C1    Firmware Revision      2.00    Number of Heads        8    Number of Cylinders    978    Sectors per Cylinder   32    Sector Size            512    Total Sectors          250368 ATA PARTITION 1 INFO    Start Sector           32    Number of Sectors      250336    Size in Bytes          128172032    File System Type       FAT16    Number of FAT Sectors  123    Sectors Per Cluster    8    Number of Clusters     31227    Number of Data Sectors 249816    Base FAT Sector        237    Base Root Sector       483    Base Data Sector       515 ATA MONLIB INFO    Image Monlib size      118124    Disk Monlib Size       116764    Disk Space Available   120832    Name                   piptom-atafslib-m    Start sector           2    End sector             230    Updated By             C3825-ADVENTERPRISEK9-M12.4(22)YB8    Version                2 C3825ISR#	C3825ISR#sh flash: filesys ******** ATA Flash Card Geometry/Format Info ******** ATA CARD GEOMETRY    Manufacturer Name    Model Number           LEXAR ATA FLASH CARD    Serial Number          41803419207322165421    Firmware Revision      20101110    Number of Heads        16    Number of Cylinders    15506    Sectors per Cylinder   63    Sector Size            512    Total Sectors          15630048 ATA PARTITION 1 INFO    Start Sector           63    Number of Sectors      15629985    Size in Bytes          8002552320    File System Type       FAT32    Number of FAT Sectors  15234    Sectors Per Cluster    8    Number of Clusters     1949935    Number of Data Sectors 15599480    Base FAT Sector        32    Base Root Sector       NA    Base Data Sector       30500    Root Cluster           2    Backup Boot Sector     0    FS Info Sector         1 ATA MONLIB INFO    Image Monlib size      118124    Disk Monlib Size       NA    Disk Space Available   NA    Name                   NA    End Sector             NA    Start sector           NA    Updated By             NA    Version                NA C3825ISR#	C3825ISR#sh flash: filesys ******** ATA Flash Card Geometry/Format Info ******** ATA CARD GEOMETRY    Manufacturer Name    Model Number           LEXAR ATA FLASH CARD    Serial Number          41803419207322165421    Firmware Revision      20101110    Number of Heads        16    Number of Cylinders    15506    Sectors per Cylinder   63    Sector Size            512    Total Sectors          15630048 ATA PARTITION 1 INFO    Start Sector           63    Number of Sectors      524225    Size in Bytes          268403200    File System Type       FAT16    Number of FAT Sectors  256    Sectors Per Cluster    8    Number of Clusters     65430    Number of Data Sectors 523440    Base FAT Sector        239    Base Root Sector       751    Base Data Sector       783 ATA MONLIB INFO    Image Monlib size      118124    Disk Monlib Size       118124    Disk Space Available   121856    Name                   piptom-atafslib-m    Start sector           2    End sector             232    Updated By             C3825-ADVENTERPRISEK9-M12.4(24)T8    Version                2 C3825ISR#

That 8G CF in the middle column is formatted with FAT32 and it's not going to boot - that's normal.

The same 8G CF was zeroed and partitioned to avoid the file-system limitations - FAT16 partition cannot be bigger than 4G and the fat table cannot address more than 2G. The first partition (256M) is formatted from the router with FAT16. Since all those activities were executed on the router, it generated even the additional ATA information appropriately (in the right column).

With the 3rd column CF we should be able to boot C3825ISR using "boot [flash-fs:][partition-number:][filename]" syntax - in this case:
boot system flash:0:c3825-adventerprisek9-mz.124-24.T8.bin

However, I'm hitting the ROMMON and the FC is not readable there

rommon 1 > set
PS1=rommon ! >
WARM_REBOOT=FALSE
BSI=0
RANDOM_NUM=397400253
BOOT=flash:0:c3825-adventerprisek9-mz.124-24.T8.bin,12;flash:c3825-adventerprisek9-mz.124-24.T8.bin,1;
RET_2_RTS=12:28:12 EST Sat Dec 20 2014
RET_2_RCALTS=1419096493
?=1
rommon 2 >

rommon 2 > dir flash:
program load complete, entry point: 0x8000f000, size: 0xcb40
open(): Open Error = -66
dir: cannot open device "flash:"
rommon 3 >

rommon 3 > boot flash:0:c3825-adventerprisek9-mz.124-24.T8.bin
illegal partition number
loadprog: error - on file open
boot: cannot load "flash:0:c3825-adventerprisek9-mz.124-24.T8.bin"
rommon 4 >

The 8G CF is the smalles one I found in the closest to my place Best Buy. It's a high speed (UDMA) one (Lexar PLATINUM II, 200x)
Most likely this type of card is not fully supported, but I wasn't able to find a clear technical explanation - just guesses around ;)
It seems like this compatibality is related somehow to the CF+ and CompactFlash specification revisions.

Any idea what is the correct explanation?

[Leo Laohoo]

I've been playing with CF and USB since 2006 and all I can say is this:  Do not just trust the "manufacturer" of the media.  For example, Lexar, Toshiba, Sandisk, etc do NOT manufacture the CF/USB thumb drive.  

All the big companies like the ones mentioned above buys them by a significant quantity and "formats" them to a certain physical shape and appearance.   This is why you'll see "strange" things like, for example, you've got two Lexar-branded CF but are different sizes.  You'll see one of the two work and the other won't.  This is because some of the real manufacturers do NOT follow the standard.  Cisco appliances support only Type 2 CF.  Same goes with USB thumb drives.  Some work, some don't (even if they are branded the same but of different sizes).  

FAT16 partition cannot be bigger than 4G and the fat table cannot address more than 2G. 

Not necessarily true.  Depends on who's doing the formating.  I've got three 8Gb Lexar Cruzer Facet and they work with Cisco routers and switches (didn't try other appliances).  The main thing to consider is I opted to format the USB thumb drives using the Cisco appliances.  

[Joseph W. Doherty]

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Posting

To add just a bit to Leo's post, you also need to realize quality of code that supports CF varies too.  Your results might vary between Cisco devices or even between same version of Cisco device with different code bases (especially bootstrap version).

[Leo Laohoo]

you also need to realize quality of code that supports CF varies too.

Good point, Joseph.  

The same USB thumb drive will work with some IOS, for example 15.0(2)SE4 and below, but won't work on  higher IOS level like 15.2(2)E and above.  This is all due to the bad IOS codes.