From 062b631dc2de25b5a3b81dfc12cf38106dfc1207 Mon Sep 17 00:00:00 2001 From: Artem Bityutskiy Date: Thu, 20 Oct 2011 17:07:17 +0300 Subject: [PATCH] UBI: mention unstable bits when bragging about power cuts and MLC Signed-off-by: Artem Bityutskiy --- faq/ubi.xml | 12 ++++++++++++ 1 file changed, 12 insertions(+) diff --git a/faq/ubi.xml b/faq/ubi.xml index 1ee4327..7133867 100644 --- a/faq/ubi.xml +++ b/faq/ubi.xml @@ -434,6 +434,12 @@ probably do this.

Yes, UBI is designed to be tolerant of power failures and unclean reboots.

+

Year 2011 note: however, there is an unsolved +unstable bits issue which may make +UBI fail to recover after a power cut on modern SLC and MLC flashes. This has +never been reported yet for UBI, but has been reported for UBIFS and we believe +must be an issue for UBI as well.

+

May UBI be used on MLC flash?

@@ -447,6 +453,12 @@ life-cycle (about 1000-10000, unlike 100000-1000000 for SLC NAND and NOR flashes), the threshold has to be set to a lower value (e.g., 256). This may be done via the Linux kernel configuration menu.

+

Year 2011 note: however, there is an unsolved +unstable bits issue which may make +UBI fail to recover after a power cut on modern SLC and MLC flashes. This has +never been reported yet for UBI, but has been reported for UBIFS and we believe +must be an issue for UBI as well.

+

Note, unlike UBI, JFFS2 uses random wear-leveling algorithm, which is in fact not completely random, because JFFS2 makes it more probable to garbage collect eraseblocks with more dirty data. This means that JFFS2 is not -- 2.49.0