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83

If you worry about write cycles, you won't get anywhere. You will have data on your SSD that changes frequently; your home, your configs, your browser caches, maybe even databases (if you use any). They all should be on SSD: why else would you have one, if not to gain speed for the things you do frequently? The number of writes may be limited, but a modern ...


47

TL/DR: Make sure you get the right device name, ensure it's not mounted, and do as many random overwrites as you can afford. You can follow it by an erase command designed for flash hardware, if you are on a recent enough distribution. In these checks, always use the drive (like /dev/sdh) and not the partition name (which would be /dev/sdh1) # dmesg|grep ...


29

Ok, so the goal is to get as much bang for the buck as possible - Speed vs. the price of replacement hardware (assuming a single large harddisk and medium-size SSD, which seems to be the norm). To simplify you can to weigh how much you notice the speed increase from moving a file to the SSD against the number of sectors written to move that file to the SSD. ...


27

I realize this isn't really an answer to your question, but the simplest way is to physically destroy the drive (smashing it repeatedly with a sledgehammer generally does the trick, but industrial shredding or incineration are also options). If you're worried enough about security to want to make sure the data is unrecoverable, the value of that data is ...


13

Using sgdisk You can use sgdisk to print detailled information: sgdisk --print <device> […] Disk /dev/sdb: 15691776 sectors, 7.5 GiB Logical sector size: 512 bytes […] When you multiply the number of sectors with the sector size you get the exact byte count that should match the output of dd. Using /sys directly You can also get those numbers ...


12

"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 ...


11

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. ...


9

Passing expert on the installer command line will tell it to enable installing to devices other than internal drives.


8

Low-level formatting means many different things to different people and on 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. ...


8

You generally don't want to write the filesystem on the entire block device (ie. /dev/sdd), you want to create a partition and then put the filesystem in there (ie. /dev/sdd1). That is also what your mkfs complained about. If you are sure you only want to have one filesystem on this disk at a time, and you don't need a bootloader, you can safely ignore this ...


8

A combination of dd and ssh can probably help here: # dd if=/dev/mtd0 | ssh me@myhost "dd of=mtd0.img"


6

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 ...


5

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]).


5

No, you should not be required to format the CF card before installing Linux. The Syba adapter should present the CF storage to the computer as a fully-writable SATA drive, and should thus allow the Linux installer to partition and format it. The fact that the installer cannot write to the CF leads me to suspect that at least one of a few things could be ...


5

You can use unetbootin to install whatever distro you want to any device. It's a standalone executable so there isn't anything to install, simply download it and run. http://unetbootin.sourceforge.net/ Unetbootin offers CentOS 5 & 6 as both the Live and regular versions.               &...


5

Btrfs uses crc32c checksums to check the integrity of blocks. If the checksum doesn't match the block when it's read then an alternative block is read. This is assuming there is an alternative (RAID1). If that block also fails or if there is no alternative an EIO (error input/output) is returned. I do not know of any way to automatically detecting errors, ...


4

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 were both from Sandisk). He found a .dll file on the functional stick and a URL inside the dll (...


4

mkfs.vfat /dev/hda1 will do the equivalent of the MSDOS "format" command.


4

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 ...


4

Traditional hard drives have a spinning disk platter. This means that filesystems can (and do) perform several optimizations. For example, it will locate segments of a file in a contiguous region of the disk, so that when you read different parts of the file, the kernel doesn't have to wait for the platter to spin to a different place. Another optimization ...


4

Both SDDs and MTDs have a lifespan and are rate to a certain number of writes. Early MTDs were rated for 1000s of erase/write cycles. Many MTDs are not actually block devices, but the Linux driver emulates it as such, and presents a block layer. Or the standard block size (512) might be much larger on the underlying hardware. If you write consecutive 512-...


4

Is there a limit to the size of this file? Not unless the file system imposes a limit. On a 4GB flash with a modern file system the answer is, you will run out of space a long before you hit the maximum file size. So no, there's no limit. Will this file be continuously written to until there is no more memory left Yes what would happen then? Your ...


3

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 ...


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 ...


3

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. ...


3

The tilde expands to "$HOME", so when you write ~/Users/Gurpreet/Desktop/target.img what you've really written is /Users/Gurpreet/Users/Gurpreet/Desktop/target.img. Just get rid of the redundancy and write one (the tilde) or the other (/Users/Gurpreet).


3

This refers to the mode the device was in when the data was collected. From the man page: Some SMART attribute values are updated only during off-line data collection activities; the rest are updated during normal operation of the device or during both normal operation and off-line testing. The Attribute value table produced by the '-A' option indicates ...


3

Yes you're correct about the middle values. Those are the data values and their ASCII representations are printed to the far most right. The addresses are in hex as well so you're seeing 16 values per row, 0000000c to 0000001c, for example. There is also a base command (type help base) which specifies what the base addresses is for the relative addresses you'...


3

A couple of ways: If you can get SMART data from an SD cart with smartctl, it may have a bytes written counter (no idea if this is possible). This will be the most accurate, as it will count all partitions and also not be lost over reboot. It may also be able to count any write-amplification caused by erase block size and/or wear-leveling. Depending on the ...


3

The manufacturer sold you the 2GB USB stick as 2 Gigabytes, meaning 2000000000 bytes. Your computer is showing the stick in units of Gigibytes. 1 Gigibyte is 1024 x 1024 x 1024 bytes, which is 1073741824 bytes. If you divide your 2000000000 by 1073741824 you'll end up with 1.86264514923095703125 or, rounded to two decimal places 1.86 GiB. In other words, ...


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