Editing CompactFlash (section)

===Reliability===
Original PC Card memory cards used an internal battery to maintain data when power was removed. The rated life of the battery was the only reliability issue. CompactFlash cards that use flash memory, like other flash-memory devices, are rated for a limited number of erase/write cycles for any "block." While NOR flash has higher endurance, ranging from 10,000 to 1,000,000, they have not been adapted for memory card usage. Most mass storage usage flash are NAND based. {{As of|2015}} NAND flash were being scaled down to 16&nbsp;nm. They are usually rated for 500 to 3,000 write/erase cycles per block before hard failure.<ref name="samsung1">{{cite web|url=http://www.samsung.com/global/business/semiconductor/products/flash/downloads/applicationnote/app_nand.pdf |title= Application Note for NAND Flash Memory (Revision 2.0) | access-date=April 8, 2010 |url-status=dead |archive-url=https://web.archive.org/web/20110616022706/http://www.samsung.com/global/business/semiconductor/products/flash/downloads/applicationnote/app_nand.pdf |archive-date=June 16, 2011 }}</ref> This is less reliable than magnetic media.<ref>The comparison is not in the same terms as for magnetic media, for which hours of operation and reads also impose wear.</ref> ''Car PC Hacks''<ref name="CarPChacks">''Car PC hacks'', Damien Stolarz, 2005, Farnham:O’Reilly Media, Sebastopol, CA, USA, {{ISBN|0-596-00871-6}}</ref> suggests disabling the Windows swap file and using its [[Enhanced Write Filter]] (EWF) to eliminate unnecessary writes to flash memory.<ref>EWF is available only in XP Embedded, not the XP Professional, Home, or Media Editions versions of Windows.</ref> Additionally, when formatting a flash-memory drive, the Quick Format method should be used, to write as little as possible to the device.

Most CompactFlash flash-memory devices limit wear on blocks by varying the physical location to which a block is written. This process is called [[wear leveling]]. When using CompactFlash in ATA mode to take the place of the [[hard disk drive]], wear leveling becomes critical because low-numbered blocks contain tables whose contents change frequently. Current CompactFlash cards spread the wear-leveling across the entire drive. The more advanced CompactFlash cards will move data that rarely changes to ensure all blocks wear evenly.

NAND flash memory is prone to frequent soft read errors.<ref name="CarPChacks" /> The CompactFlash card includes [[error checking and correction]] (ECC) that detects the error and re-reads the block. The process is transparent to the user, although it may slow data access.

As a flash memory device is [[solid-state drive|solid-state]], it is less affected by physical shock than a spinning disk.

The possibility for electrical damage from upside-down insertion is prevented by asymmetrical side slots, assuming that the host device uses a suitable connector.

====Power consumption and data transfer rate====
Small cards consume around 5% of the power required by small disk drives and still have reasonable transfer rates of over 45&nbsp;MB/s for the more expensive 'high-speed' cards.<ref>{{cite web|url=http://www.photokina-show.com/0365/sandisk/flashmemorycard/sandiskextreme4/|title=SanDisk Extreme IV review|last=LetsGoDigital|website=www.photokina-show.com|access-date=18 March 2018}}</ref> However, the manufacturer's warning on the flash memory used for [[ReadyBoost]] indicates a current draw in excess of 500 mA.

====File systems====
CompactFlash cards for use in consumer devices are typically formatted as [[FAT12]] (for media up to 16&nbsp;MB), [[FAT16]] (for media up to 2&nbsp;GB, sometimes up to 4&nbsp;GB) and [[FAT32]] (for media larger than 2&nbsp;GB). This lets the devices be read by personal computers but also suits the limited processing ability of some consumer devices such as [[digital camera|camera]]s.

There are varying levels of compatibility among FAT32-compatible cameras, MP3 players, PDAs, and other devices. While any device that claims FAT32-capability should read and write to a FAT32-formatted card without problems, some devices are tripped up by cards larger than 2&nbsp;GB that are completely unformatted, while others may take longer to apply a FAT32 format.

The way many digital cameras update the file system as they write to the card creates a FAT32 bottleneck. Writing to a FAT32-formatted card generally takes a little longer than writing to a FAT16-formatted card with similar performance capabilities. For instance, the [[Canon EOS 10D]] writes the same photo to a FAT16-formatted 2&nbsp;GB CompactFlash card somewhat faster than to a same speed 4&nbsp;GB FAT32-formatted CompactFlash card, although the memory chips in both cards have the same write speed specification.<ref>{{cite web |url=http://www.robgalbraith.com/bins/content_page.asp?cid=7-6453-6837 |website=Rob Galbraith |title=CompactFlash Performance Database updated |archive-url=https://web.archive.org/web/20130518120000/http://robgalbraith.com/bins/content_page.asp?cid=7-6453-6837 |archive-date=2013-05-18 |url-status=dead |date=March 22, 2004 }}</ref> Although FAT16 is more wasteful of disk space with its larger clusters, it works better with the write strategy that flash memory chips require.

The cards themselves can be formatted with any type of file system such as [[Extended file system|Ext]], [[JFS (file system)|JFS]], [[NTFS]], or by one of the dedicated [[flash file system]]s. It can be divided into partitions as long as the host device can read them. CompactFlash cards are often used instead of hard drives in embedded systems, [[dumb terminal]]s and various small form-factor PCs that are built for low noise output or power consumption. CompactFlash cards are often more readily available and smaller than purpose-built [[solid-state drive]]s and often have faster [[seek time]]s than hard drives.