MicroSD

From Openmoko

(Difference between revisions)
Jump to: navigation, search
(References: +link)
(References: more)
Line 20: Line 20:
 
*[[MicroSD]](HC) cards are a sort of a SSD: [http://robert.penz.name/137/no-swap-partition-journaling-filesystem-on-a-ssd/ December 7, 2008, robert.penz.name:  No SWAP Partition, Journaling Filesystems, … on a SSD?] Quote: "...They assume perfect wear leveling...We stay also with the 2 million cycles and assume a 16GB SSD *With 50 MByte/sec we get 20 years! *With 2 MByte/sec we get 519 years! *And even if we reduce the write cycles to 100.000 and write with 2 MByte/sec all the time we’re at 26 years!!...1.  Never choose to use a journaling file system on the SSD partitions: Bullshit, you’re just risking data security. Stay with ext3...7. One more thing to consider is that flash-devices handle their space in blocks. The blocksize typically varies between 16KB and 512 KB. Therefore writing one byte may cause erase and rewrite of up to 512KB..."
 
*[[MicroSD]](HC) cards are a sort of a SSD: [http://robert.penz.name/137/no-swap-partition-journaling-filesystem-on-a-ssd/ December 7, 2008, robert.penz.name:  No SWAP Partition, Journaling Filesystems, … on a SSD?] Quote: "...They assume perfect wear leveling...We stay also with the 2 million cycles and assume a 16GB SSD *With 50 MByte/sec we get 20 years! *With 2 MByte/sec we get 519 years! *And even if we reduce the write cycles to 100.000 and write with 2 MByte/sec all the time we’re at 26 years!!...1.  Never choose to use a journaling file system on the SSD partitions: Bullshit, you’re just risking data security. Stay with ext3...7. One more thing to consider is that flash-devices handle their space in blocks. The blocksize typically varies between 16KB and 512 KB. Therefore writing one byte may cause erase and rewrite of up to 512KB..."
 
*'''Please note: SDHC-cards test - not ''Micro''SDHC-cards''': [http://www.tomshardware.com/charts/sdhc-memory-card-charts/File-Server-Benchmark-Pattern,865.html tomshardware.com: SDHC Memory Card Charts > File Server Benchmark Pattern: File Server Benchmark Pattern] Quote: "...IOMeter 2003.05.10 (Total I/O operations per second for Queuedepth 1 - 64)...", [http://www.tomshardware.com/charts/sdhc-memory-card-charts/benchmarks,40.html All SDHC Memory Card Charts]
 
*'''Please note: SDHC-cards test - not ''Micro''SDHC-cards''': [http://www.tomshardware.com/charts/sdhc-memory-card-charts/File-Server-Benchmark-Pattern,865.html tomshardware.com: SDHC Memory Card Charts > File Server Benchmark Pattern: File Server Benchmark Pattern] Quote: "...IOMeter 2003.05.10 (Total I/O operations per second for Queuedepth 1 - 64)...", [http://www.tomshardware.com/charts/sdhc-memory-card-charts/benchmarks,40.html All SDHC Memory Card Charts]
 +
*[http://www.sunhelp.org/pipermail/geeks/2008-February/061492.html 2008 (geeks) Flash wear leveling] Quote: "...We tested several file systems (ext2/3, xfs, reiserfs, FAT, ...) and finaly gave up...and developed an application speciffic log structured file system in userland..."
 +
*MicroSD(HC) can be tested via a USB flash adaptor and H2testw - backup your data before testing: [http://sosfakeflash.wordpress.com/2008/09/02/h2testw-14-gold-standard-in-detecting-usb-counterfeit-drives/ September 2, 2008, sosfakeflash.wordpress.com: H2testw 1.4 – Gold Standard In Detecting USB Counterfeit Drives], [http://www.bloggersbase.com/computers/h2testw-fix-usb/ bloggersbase.com: H2testw - Fix Your USB!], [http://www.heise.de/software/download/h2testw/50539 H2testw 1.4]
  
 
[[Category:MicroSD| ]]
 
[[Category:MicroSD| ]]

Revision as of 14:14, 17 January 2010

microSD is the format of the removable flash memory cards used in Neo 1973 and Neo Freerunner devices. Additionally the Neo Freerunner support microSDHC.

For more informations about this format see microSD on Wikipedia.

A list of supported cards can be found at Supported microSD cards.

Importent features

Importent note: Wear-leveling and ECC error correction and detection is not part of the SD card specification (version 2.0 SDHC), so please check for yourself that the SD(HC)-card support and use:

  • built-in ECC error correction and detection
  • Wear Leveling technology

If the manufacturer advertises the card with e.g. 1,000,000 hours MTBF, it might be a strong indication that the above features are used.

Other importent specifications are:

  • Low power consumption
  • Number of insertions the card endures - 10,000 seems to be good quality.
  • Total I/O operations per second

References

Personal tools

microSD is the format of the removable flash memory cards used in Neo 1973 and Neo Freerunner devices. Additionally the Neo Freerunner support microSDHC.

For more informations about this format see microSD on Wikipedia.

A list of supported cards can be found at Supported microSD cards.

Importent features

Importent note: Wear-leveling and ECC error correction and detection is not part of the SD card specification (version 2.0 SDHC), so please check for yourself that the SD(HC)-card support and use:

  • built-in ECC error correction and detection
  • Wear Leveling technology

If the manufacturer advertises the card with e.g. 1,000,000 hours MTBF, it might be a strong indication that the above features are used.

Other importent specifications are:

  • Low power consumption
  • Number of insertions the card endures - 10,000 seems to be good quality.
  • Total I/O operations per second

References