MicroSD

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A list of supported cards can be found at [[Supported microSD cards]].
 
A list of supported cards can be found at [[Supported microSD cards]].
  
==Importent features==
+
==Important features==
Importent note: [http://en.wikipedia.org/wiki/Wear_levelling 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:
+
Important note: [http://en.wikipedia.org/wiki/Wear_levelling 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
 
*built-in ECC error correction and detection
 
*Wear Leveling technology
 
*Wear Leveling technology
If the manufacturer advertises the card with e.g. 1.000.000 hours [http://en.wikipedia.org/wiki/Mean_time_between_failures MTBF], it might be a strong indication that the above features is used.
+
If the manufacturer advertises the card with e.g. 1,000,000 hours [http://en.wikipedia.org/wiki/Mean_time_between_failures MTBF], it might be a strong indication that the above features are used.
  
Other importent specifications are:
+
Other important specifications are:
 
*Low power consumption
 
*Low power consumption
 +
*Number of insertions the card endures - 10,000 seems to be good quality.
 +
*Total I/O operations per second
 +
 +
==Use==
 +
*A log-structured file system (e.g. [[NILFS2]]) when available, ought to be a good choice because of the continuous snapshotting.
  
 
==References==
 
==References==
 
*[http://www.notebookreview.com/default.asp?newsID=4258 2/17/2008, notebookreview.com: SDHC Cards vs Hard Drive vs SSD] Quote: "...That sounds like an absolutely manditory thing to have in flash storage ... and luckily "high-performance" SDHC cards such as the 16GB A-DATA SDHC card and many other class 6 cards from other manufacturers incorportate wear-leveling [Please check before you buy!]..."
 
*[http://www.notebookreview.com/default.asp?newsID=4258 2/17/2008, notebookreview.com: SDHC Cards vs Hard Drive vs SSD] Quote: "...That sounds like an absolutely manditory thing to have in flash storage ... and luckily "high-performance" SDHC cards such as the 16GB A-DATA SDHC card and many other class 6 cards from other manufacturers incorportate wear-leveling [Please check before you buy!]..."
 
*[[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]
 +
 +
==External links==
 +
*MicroSD(HC) flash cards can be tested via a USB flash adaptor and H2testw. Please 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!] Quote: "...H2testw was developed to test USB sticks for various kinds of errors. It can also be used for any other storage media like memory cards, internal and external hard drives and even network volumes...", [http://www.heise.de/software/download/h2testw/50539 H2testw 1.4]
  
 
[[Category:MicroSD| ]]
 
[[Category:MicroSD| ]]

Latest revision as of 13:43, 10 June 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.

Contents

[edit] Important features

Important 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 important specifications are:

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

[edit] Use

  • A log-structured file system (e.g. NILFS2) when available, ought to be a good choice because of the continuous snapshotting.

[edit] References

[edit] External links

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 is used.

Other importent specifications are:

  • Low power consumption

References

  • 2/17/2008, notebookreview.com: SDHC Cards vs Hard Drive vs SSD Quote: "...That sounds like an absolutely manditory thing to have in flash storage ... and luckily "high-performance" SDHC cards such as the 16GB A-DATA SDHC card and many other class 6 cards from other manufacturers incorportate wear-leveling [Please check before you buy!]..."
  • MicroSD(HC) cards are a sort of 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..."