From: Artem Bityutskiy Date: Thu, 20 Oct 2011 08:53:04 +0000 (+0300) Subject: UBIFS: move section about power cuts from FAQ to docs X-Git-Url: https://www.infradead.org/git/?a=commitdiff_plain;h=515575d826eed9b98f74f1fdf41e978743ebc6b9;p=mtd-www.git UBIFS: move section about power cuts from FAQ to docs Signed-off-by: Artem Bityutskiy --- diff --git a/doc/ubifs.xml b/doc/ubifs.xml index 4f29e79..dd3d37c 100644 --- a/doc/ubifs.xml +++ b/doc/ubifs.xml @@ -14,6 +14,7 @@
  1. Big red note
  2. Overview
    3. +
  3. Power-cuts tolerance
  4. Source code
  5. Mailing list
  6. User-space tools
    7. @@ -110,7 +111,7 @@ subsystems involved:

    journal, but UBIFS does not need to scan whole media, so it anyway takes fractions of a second to mount UBIFS; note, authors payed special attention to this UBIFS aspect, see - this FAQ entry; + here;
  7. fast I/O - even with write-back disabled (e.g., if UBIFS is mounted with the "-o sync" mount option) UBIFS shows good @@ -160,6 +161,47 @@ subsystems involved:

    +

    Power-cuts tolerance

    + +

    Both UBI (see here) and UBIFS are +tolerant to power-cuts, and they were designed with this property in mind.

    + +

    UBIFS has internal debugging infrastructure to emulate power failures and +the authors used it for extensive testing. It was tested for long time with +power-fail emulation. The advantage of the emulation is that it emulates power +failures even at the situations which happen not very often. For example, when +the master node is updated, or the log is changed. The probability to interrupt +the system at those moments is very low in real-life.

    + +

    There is also a powerful user-space test program called integck +which performs a lot of random I/O operations and checks the integrity of the +FS after remount. This test can also handle emulated power-cuts and check the +FS integrity.

    + +

    Real power-cut tests have also done on OneNAND flash. We used Power +Node devices which are controlled via serial line and may switch the power of +the connected device on and off. UBIFS survived more than 100000 power-cuts +while running stress tests.

    + +

    We've also done real power-cut tests on Spansion NOR flash. Some problems +were found, but they were fixed and the board survived 10000 power-cuts after +this. Please, see related discussions at the +MTD mailing list. The thread has +"UBIFS Corrupt during power failure" subject. The beginning of the thread +may be found +here, +then it continues +here, +and then continues +here, +and +here, +and +here. +

    + + +

    Source code

    UBIFS is in mainline since 17 July 2008 and the first kernel release which diff --git a/faq/ubifs.xml b/faq/ubifs.xml index e7aaa40..7d0af9a 100644 --- a/faq/ubifs.xml +++ b/faq/ubifs.xml @@ -33,7 +33,6 @@

  8. How do I disable compression?
  9. How do I use UBIFS with nandsim?
  10. How do I extract files from an UBI/UBIFS image?
    11. -
  11. Is UBIFS tolerant to power-cuts?
  12. I need more space - should I make UBIFS journal smaller?
  13. Why is my file empty after an unclean reboot?
  14. Why does my file have zeroes at the end after an unclean reboot?
    15. @@ -1049,43 +1048,6 @@ rmmod ubifs ubi nandsim -

    Is UBIFS tolerant to power-cuts?

    - -

    Yes, both UBI (see here) and UBIFS are -tolerant to power-cuts, and they were designed with this property in mind.

    - -

    UBIFS has internal debugging infrastructure to emulate power failures and -the authors used it for extensive testing. It was tested for long time with -power-fail emulation (see here). -The advantage of the emulation is that it emulates power failures even at the -situations which happen not very often. For example, when the master node is -updated, or the log is changed. The probability to interrupt the system at -those moments is very low in real-life.

    - -

    Real power-cut tests have also done on OneNAND flash. We used Power -Node devices which are controlled via serial line and may switch the power of -the connected device on and off. UBIFS survived more than 100000 power-cuts -while running stress tests.

    - -

    We've also done real power-cut tests on Spansion NOR flash. Some problems -were found, but they were fixed and the board survived 10000 power-cuts after -this. Please, see related discussions at the -MTD mailing list. The thread has -"UBIFS Corrupt during power failure" subject. The beginning of the thread -may be found -here, -then it continues -here, -and then continues -here, -and -here, -and -here. -

    - - -

    I need more space - should I make UBIFS journal smaller?

    UBIFS journal is very different to ext3 journal. In case of ext3, the