I doubt if CF is reliable to replace IDE disks. I own a CF digital camera and have experienced data loss. It seems that data loss/file corruption is quite common on CF. Any different experience?
Dave
From: "Richard A. Smith" rsmith@bitworks.com Reply-To: "Richard A. Smith" rsmith@bitworks.com To: "linuxbios@clustermatic.org" linuxbios@clustermatic.org Subject: Re: AW: DOC vs. IDE Date: Wed, 23 Oct 2002 16:28:28 -0500
On Wed, 23 Oct 2002 14:28:23 -0600 (MDT), Ronald G Minnich wrote:
On Wed, 23 Oct 2002, Christopher Bergeron wrote:
That actually sounds like a brilliant idea. I wonder if anyone on the list can confirm performance... does the CFcard appear as a standard
IDE
disk or is there a driver or anything necessary?
we're doing it here on the PCM-5823-A2 geode cards. We use CF as
/dev/hdc,
there is no /dev/hd1. Works fine.
I'll pipe in a little bit of personal experience here. If you are _just_ using a CF with an IDE adapter then all is well and things will work great.
During bringup and debug though its nice to have a big HD with a full linux distribution on on it so you can develope on your target.
However if you are using a CF _and_ a normal IDE drive you may run into a gotcha. In the 2.2 linux IDE code there are clauses that if a CF device is dectected on hda it will NOT probe for hdb. Same goes for hdc and hdd. There is no output telling you its skipping it either. Apparently there were some early CF devices that did some funky stuff with the diag signal (drive dection) and Andre (the 2.2 IDE maintainer) chose to blacklist all CF devices.
The fix is to feed the kernel some parameter like ide0=flash or something similar to make it go ahead and probe.
I haven't looked at the 2.4.x IDE code so I don't know if it carried over or not.
But if you mysteriously don't have an hdb with a CF hooked up in your system go check the IDE probing code before you pull you hair out trying to figure out whats wrong with your hardware like I did.
-- Richard A. Smith Bitworks, Inc. rsmith@bitworks.com 479.846.5777 x104 Sr. Design Engineer http://www.bitworks.com
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On Wed, 23 Oct 2002, Dave Dworin wrote:
I doubt if CF is reliable to replace IDE disks. I own a CF digital camera and have experienced data loss. It seems that data loss/file corruption is quite common on CF. Any different experience?
I don't think your sample set is really exhaustive enough to say it is CF, your camera type, your specific camera, etc.
But we have had very little trouble with CF here.
ron
Are you using CFdisks with WinXP? WinXP has a nasty habit (WINDOWS? NASTY HABIT??? NOOO!!!) of formatting CFdisks with Fat32 by default whereas most cameras use Fat16 (from what I've heard). As such, I've heard quite a few horror stories of data loss "because of CFdisks" when the actual problem was a faulty OS vendor. I just can't seem to remember the name of that vendor right now, oh well.
:)
All other indications of CompactFlash are that it's a realiable medium (unless you can document otherwise). I will provide documentation to the Fat32/Fat16/Xp issue upon request [or just search google].
-CB
Wednesday, October 23, 2002, 11:48:30 PM, you wrote:
RGM> On Wed, 23 Oct 2002, Dave Dworin wrote:
I doubt if CF is reliable to replace IDE disks. I own a CF digital camera and have experienced data loss. It seems that data loss/file corruption is quite common on CF. Any different experience?
RGM> I don't think your sample set is really exhaustive enough to say it is CF, RGM> your camera type, your specific camera, etc.
RGM> But we have had very little trouble with CF here.
RGM> ron
RGM> _______________________________________________ RGM> Linuxbios mailing list RGM> Linuxbios@clustermatic.org RGM> http://www.clustermatic.org/mailman/listinfo/linuxbios
On Thu, 24 Oct 2002 00:42:50 -0400, Christopher Bergeron wrote:
All other indications of CompactFlash are that it's a realiable medium (unless you can document otherwise). I will provide documentation to
Well I don't know that I can "document" but I've had numerious problems with CF devices. I've got 5 seperate CFs with Sector 0 CRC problems. 3 of them are SanDisk but I also have 2 from SST. They are various sizes.
This topic has come up on the Linux-embedded list as well. Others have experienced the same type of issues we have.
I've spoken with an app engineer at SanDisk and his explaniation was under certian conditions, like say if your 5V power glitches. The internal write state machine gets confused/reset or whatever and it ends up munging sector 0. After which the CF won't work in any OS (including Linux) because it throws and error reading the partition table.
The SanDisk guy told me I sould be able to recover sector 0 by writing all zeros to it which will reset the crc but I haven't been able to find an application that is 1) Freeware and 2) Will do raw sector writes.
-- Richard A. Smith Bitworks, Inc. rsmith@bitworks.com 479.846.5777 x104 Sr. Design Engineer http://www.bitworks.com
On Thu, 24 Oct 2002 12:36:48 -0500 "Richard A. Smith" rsmith@bitworks.com wrote:
The SanDisk guy told me I sould be able to recover sector 0 by writing all zeros to it which will reset the crc but I haven't been able to find an application that is 1) Freeware and 2) Will do raw sector writes.
'dd' ?
On Thu, 24 Oct 2002 21:27:21 +0100, Ian Molton wrote:
The SanDisk guy told me I sould be able to recover sector 0 by writing all zeros to it which will reset the crc but I haven't been able to find an application that is 1) Freeware and 2) Will do raw sector writes.
'dd' ?
dd would work if the device was present. But you can't dd to a device you don't have. When the IDE code attempts to read the partition table of the disk it chokes and never inserts the device into the device tree. I guess that probally should be considered a bug in the IDE code but some might call it a feature.
Note all this info is from 2.2.x.. Stand by.. Yep just checked with 2.4.18 and its still the same. Well almost, it actually does have the device in the device tree but on any access to the device it attempts to read the partition table and thus gets an IO error and fails.
Suposedly there are some IDE low level raw access IOCTLS that can send commands directly to the IDE controller but I've not investigated it yet.
-- Richard A. Smith Bitworks, Inc. rsmith@bitworks.com 479.846.5777 x104 Sr. Design Engineer http://www.bitworks.com
On Thu, Oct 24, 2002 at 04:17:47PM -0500, Richard A. Smith wrote:
Suposedly there are some IDE low level raw access IOCTLS that can send commands directly to the IDE controller but I've not investigated it yet.
Check out "IDE Taskfile Access" CONFIG_IDE_TASK_IOCTL in 2.4.19.
//Peter
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Christopher Bergeron -
Dave Dworin -
Ian Molton -
Peter Stuge -
Richard A. Smith -
Ronald G Minnich