Hot answers tagged flash-memory
7
"Low level formatting" was done on floppies, where you could write at different densities by choosing to organize the tracks and sectors differently. But this makes no sense for most modern media. Its notion of how to organize the data on the device is fixed and unchangeable. It doesn't make any sense at all for flash, which has discrete bits, rather than ...
5
There is a new dm target called "snapshot-merge".
If you format your USB flash memory as a LVM physical volume, and then locate your desired filesystem atop it in a logical volume, you can
Activate a volume group containing your USB flash memory and another LVM physical volume on a local disk.
Create a snapshot of the logical volume on the local disk.
...
4
There is no way to do a low-level format on most flash devices, since they have an additional translation layer from USB/ATA/SD/etc. to MTD which obscures the low-level MTD devices (which can be low-level formatted if gotten to directly [which you can't]).
3
Was the name of the device U167CONTROLLER before?
It may be that the microcontroller on the device has encountered some abnormal condition (totally possible with less than totally reputable manufacturers) and needs to be reprogrammed. This is a bit of a black art and it's likely you will only find Windows programs that can reprogram the microcontroller.
...
3
The mount command has two related options:
sync All I/O to the filesystem should be done synchronously.
dirsync All directory updates within the filesystem should be done synchronously.
You can specify them in the mount command's -o option:
mount -o sync /mnt/flashdrive
Or in your /etc/fstab's fourth column:
/dev/sdb1 /mnt/flashdrive ...
2
This seems a use case for dm-userspace+cowd: in essence, you would set up a DM target (block device) consisting of a COW (copy-on-write) file and the block device corresponding to your USB stick, and use it to host a filesystem. All updates would go to the COW file; reads which are not in the COW file would be served off the USB stick; after you unmount the ...
2
If we look at the source code of driver in the Linux kernel (drivers/mtd/nand/alauda.c), we see that the mtd device should be called "alauda".
For example, in cmx270_nand.c mtd name is cmx270-0. In kernel log information about it, looks like:
Creating 1 MTD partitions on "NAND 512MiB 3,3V 8-bit":
0x00000000-0x20000000 : "cmx270-0"
Check dmesg (grep ...
2
It would be more proper to say Flash Memory has only a limited number of erase cycles, these caused eventually by writes. There are many good articles available about this distinction.
When you mention burning a Linux image into router firmware, that is probably NOR flash or an EEProm. NOR is the type of flash with quicker reads, NAND the type with quicker ...
2
The /tmp and /var directories are the ones that many system programs write to a lot, and depend on being writeable. Minimizing writes to these directories, or configuring Linux to mount these directories on external storage devices that are replaceable, as opposed to on board flash, would go a long way towards accomplishing your goal.
/home and swap ...
2
use dd command for this dd if=/dev/zero of=/dev/hda
This will destroy ALL data on the hard drive, all boot sector info and all data on all partitions. It will not however render the disk useless, you simply have a clean disk that only needs to have partitions created and a new boot sector installed, which will happen when you install any OS including Linux ...
2
Your looking for a distribution, optimized for flash disk installation? I believe the concept of flash must be expounded. As you already knew, an SSD is not directly controlled. Firmware exists, as an intermediate, which controls the physical read/write process. Additionally as you understood, SSD firmware has a multitude of longevity features included.
...
2
You can do this by arranging for the device to be mounted with the sync option. But it's not such a good idea, because this can wear cheap USB flash drives very fast (this has been discussed on the Linux kernel mailing list).
Recent versions of Linux have the flush option for FAT filesystems, which is somewhere between sync and async: it causes all delayed ...
2
Low-level formatting means many different things to different people and different contexts.
The original meaning was a step needed in the formatting of disks - disk drives need header, sync and other patterns written on the media before it can store data to it. In this way the head can detect when it is A) on a track and B) where it is on the track. ...
2
Create a third, tiny, partition to hold your data. Any other location on your disk will sooner or later bring trouble if indeed you cannot rely on the filesytems.
Sometimes the last few clusters of a disk cannot be addressed in the FAT entry, that may be an option but it heavily depends on exact size of the device.
Does the embedded CPU / device have ...
1
The correct answer was given by Mechanical Snail(check the comments above). The answer's brief and simple, every Flash device uses a MLC because it is cheap and has a higher density. Giving SLC to the customer would make the pendrive costly as cost per gigabyte for SLC is more than MLC. For uses like these MLC is always preferred over SLC.
1
The following script creates a random file (around 100M) in shared memory, calculates its checksum, then copy it to the given block device several times so that the whole device is filled with copies of the random data, while reading it again and calculating its checksum to check if it does match the original one.
It produces output like:
We will create a ...
1
In my experience, hard disks that start showing problems have a few hours of (somewhat) useful life left. Turn it off, get a replacement and pray to assorted $DEITIES that the data can be saved.
I haven't had hand-on experience with failing memory sticks, but the discussions I've seen point in the same direction: If it starts showing problems, it is drawing ...
1
Take a look at this page: http://www.ardamis.com/2009/07/02/usb-drive-unusable-unformattable-and-reporting-0-bytes-capacity/
.. interesting reading. In short, the author, running Win OS, examined a functioning USB-stick (the faulty stick and the functional one where both from Sandisk). He found a .dll file on the functional stick and a URL inside the dll ...
1
All decent flash devices perform internal wear leveling so the journal won't wear them out ( too ) prematurely, so ext4 is fine from that perspective. The problem with using most unix filesystems across multiple computers is permissions. If the different computers do not have the same set of users with the same UIDs, the ownership will be wrong. For this ...
1
remove (rmmod) the ums-alauda driver
after plugging in the device, check if module alauda's probe print is seen via dmesg
if device /dev/mtd0 not seen, rmmod alauda, and insmod it again
there shouldnt be a need to mknod.
(try with the 'lid' shut).
1
Perhaps, you could make use of the seeding feature of btrfs (pointed out at http://en.wikipedia.org/wiki/Btrfs#cite_ref-16) -- to seed a read-write fs with a read-only base.
Then you'll face the problem of syncing it back to the removable storage.
I don't know of a btrfs-level feature similar to lvconvert --merge; so you could use some higher level tools ...
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