Ftl ios vs pc
Please, take into account the date of this writing (). Well, there is no simple answer, and the following is what UBIFS developers think. Very often people ask questions like “why would one need to use raw flash and why not just use eMMC, or something like this?”. All these things are not normally needed for block devices. UBIFS utilizes UBI, which is doing stuff like wear-leveling and bad eraseblock handling. UBIFS takes care of writing all data out-of-place, doing garbage-collection and so on. In other words, it assumes the device has eraseblocks, which may be written to, read from, or erased. It doesn’t work with block devices and it assumes the raw flash device model. UBIFS file system has been designed for raw flash. Please, refer this table for the some more details about the difference between block devices and raw flashes.
#Ftl ios vs pc software#
In case of FTL devices these constraints and issues are hidden, but in case of raw flash the software has to deal with them. They have different work model, they have tighter constraints and more issues than block devices. Raw flash devices are very different to block devices. Those are mostly various handheld devices and embedded systems. For example, you may use FAT file system on your MMC card, or ext3 file system or your SSD.Īlthough most flashes on the commodity hardware have FTL, there are systems which have bare flashes and do not use FTL. So the idea is that the same software may be used with FTL devices. Linux has many file systems and the block I/O subsystem, which includes elevators and so on which have been created to work with block devices (historically – hard drives). For example hard drives are block devices. Linux has an abstraction of a block device. By block-based access we mean that whole device is represented as an linear array of (usually 512-byte) blocks. But all of them provide block-based access to the device. Well, the interfaces are different and they are defined by different specifications, e.g., MMC, eMMC, SD, USB mass storage, ATA, and so on. Similarly, MMC, eMMC, SD, SSD, and other FTL devices have a built-in controller which runs FTL firmware.Īll FTL devices have an interface which provides block I/O access. Some USB flash drives are known to have quite powerful ARM processors inside. For example, if you look inside an USB flash drive, you’ll find there a NAND chip (or several of them), and a micro-controller, which runs FTL firmware. However, nowadays FTL is usually firmware, and it is run by the controller which is built into the storage device.
#Ftl ios vs pc driver#
So the host computer had to run the FTL software driver which implemented PCMCIA FTL. For example, old PCMCIA flash devices were essentially raw flash devices, and the PCMCIA standard defined the media storage format for them. At early days FTL ran on the host computer. FTL stands for “Flash Translation Layer” and it is software which emulates a block device on top of flash hardware.