File Systems - Revision history

Tim Bird: /* F2FS */

2013-03-07T01:11:14Z

‎F2FS

Tim Bird: /* F2FS */ add f2fs entry and link to page

2013-03-07T01:10:58Z

‎F2FS: add f2fs entry and link to page

Tim Bird: /* Embedded Filesystems */

2013-03-07T01:10:27Z

‎Embedded Filesystems

Wmat: Added the ELC2013 Contest section

2013-02-13T18:01:55Z

Added the ELC2013 Contest section

Tim Bird: /* UBIFS */

2012-10-12T19:25:12Z

‎UBIFS

Tim Bird: /* Comparison of flash filesystems */

2012-10-12T18:54:34Z

‎Comparison of flash filesystems

Tim Bird at 18:36, 12 October 2012

2012-10-12T18:36:54Z

Tim Bird: /* UBIFS */

2012-10-12T16:11:18Z

‎UBIFS

Tim Bird: /* InitRAMFS */ add link to landley docs on initramfs

2012-07-17T21:59:39Z

‎InitRAMFS: add link to landley docs on initramfs

Tim Bird: /* eMMC and UFS */

2012-06-26T20:20:36Z

‎eMMC and UFS

@@ Line 89: / Line 89: @@
 == F2FS ==
-[[F2FS]][http://en.wikipedia.org/wiki/F2FS (wikipedia entry)] is a flash-friendly file system for Linux, developed by Samsung.
+* [[F2FS]][http://en.wikipedia.org/wiki/F2FS (wikipedia entry)] is a flash-friendly file system for Linux, developed by Samsung.
 == InitRAMFS ==

@@ Line 89: / Line 89: @@
 == F2FS ==
-[F2FS][http://en.wikipedia.org/wiki/F2FS (wikipedia entry)] is a flash-friendly file system for Linux, developed by Samsung.
+[[F2FS]][http://en.wikipedia.org/wiki/F2FS (wikipedia entry)] is a flash-friendly file system for Linux, developed by Samsung.
 == InitRAMFS ==

@@ Line 87: / Line 87: @@
 *[http://en.wikipedia.org/wiki/Cramfs CRAMFS] - A compressed read-only file system for Linux. The maximum size of CRAMFS is 256MB.
 ** "Linear Cramfs" is the name of a special feature to use uncompressed file, in a linear block layout with the Cramfs file system.  This is useful for storing files which can be executed in-place.  For more information on Linear Cramfs, see [[Application XIP]]
 == InitRAMFS ==

← Older revision		Revision as of 18:01, 13 February 2013
Line 1:		Line 1:
		+	==[[File:Robot64x64.png]] ELC2013 Tech Zone Contest==
		+	<div style="margin:0; margin-top:10px; margin-right:10px; border:1px solid #dfdfdf; padding:0 1em 1em 1em; background-color:#ffffcc; align:right; ">
		+	To add a link to your new page use the following wiki link format:
		+
		+	<nowiki>[[My New Page]]</nowiki>
		+
		+	Save this page/section and your new page link will appear in Red. Click it and begin editing your new page. Remember to conduct all Discussions on the Discussion page associated to every wiki page. The link is at the top, directly above the page title.
		+	</div>
		+	----
		+
		+	==Introduction==
	This page has information about file systems which are of interest for embedded projects.		This page has information about file systems which are of interest for embedded projects.

@@ Line 166: / Line 166: @@
 == UBIFS ==
-UBIFS is a flash-based filesystem, implemented on top of the Unsorted Block Images ([[File_Systems#UBI|UBI]]) interface.
+[[UBIFS]] is a flash-based filesystem, implemented on top of the Unsorted Block Images ([[File_Systems#UBI|UBI]]) interface.
 It has good performance compared to Jffs2 and yaffs.

@@ Line 338: / Line 338: @@
 == Comparison of flash filesystems ==
-See [[Flash_Filesystem_Benchmarks]]
+=== Free Electrons tests (2011) ===
 = Other projects =

@@ Line 102: / Line 102: @@
 == LogFS ==
-*[http://logfs.org/logfs/ logfs] - LogFS is a scalable flash filesystem. It is aimed to replace
+LogFS was a scalable flash filesystme aimed at replacing JFFS2 for most uses.
-JFFS2 for most uses, but focuses more on the large devices.
-Matt Mackall writes (in July of 2007):
+Unfortunately, it seems to be abandoned at present.
- LogFS is a filesystem designed to support large volumes on FLASH. It
+See [[LogFS]] for details.
- uses a simple copy-on-write update process to ensure consistency (the
- "log" in the name is a historical artifact). It's easily the most
- modern and scalable open-source FLASH filesystem available for Linux
- and it's well on its way to being accepted in the mainline tree.
 == NFS ==

@@ Line 183: / Line 183: @@
 == UBIFS ==
-[http://www.linux-mtd.infradead.org/doc/ubifs.html UBIFS] is a filesystem that works on top of [http://elinux.org/File_Systems#UBI UBI] volumes
+It has good performance compared to Jffs2 and yaffs.
-* UBIFS presentation slides: [http://www.linux-mtd.infradead.org/doc/ubifs.odp ubifs.odp]
+Please see the [[UBIFS]] page for more details.
-−
-=== UBIFS vs. YAFFS2 comparisons for 2.6.31.1 ===
-−
-First, see our [[Flash_Filesystem_Benchmarks]] for more recent benchmarks.
-−
-Hardware: MIPS, 403MHz CPU, 1GB Nand Flash
-−
-IOZone results: 4M, 8M & 16M file sizes in 980MB partition.
-−
-* mount time
-** "1st mount" : time for mounting just after "flash_eraseall".
-** "Empty" : time for mounting after "1st mount".(there's no files in partition)
-** "Full" : time for mounting after creating files util the partition is full.(file size is random.)
-** "Ubiattach" time for attaching 980MB partition into the ubi layer using ubiattach util.
-−
-{|border="1" cellpadding="5" cellspacing="0"
-|-bgcolor="#aaaaaa"
-!           !! Ubiattach !! Ubifs !! Yaffs2
-|-
-| 1st mount || 2.59 sec || 0.17 sec  || 2.25 sec
-|-
-| Empty     || 2.57 sec || 0.11 sec  || 0.03 sec
-|-
-| Full      || 2.63 sec || 0.16 sec  || 0.80 sec
-|-
-|}
-−
-−
-* IOZone results
-−
-{|border="1" cellpadding="5" cellspacing="0"
-|+ align="top" | UBIFS compared to YAFFS2 (file size = 4MB)
-|-
-! 4M !! write !! rewrite !! read !! reread !! r.read !! r.write !! b.read !! r.rewrite !! s.read !! fwrite !! frewrite !! fread !! freread
-|- align="right"
-| align="center" | yaffs2 || 1538 || 1527 || 296962 || 297696 || 297825 || 1521 || 296876 || 1526 || 295164 || 1536 || 1524 || 297436 || 299021
-|- align="right"
-| align="center" | ubifs || 19913 || 20989 || 298346 || 297631 || 299809 || 20968 || 298368 || 20181 || 299458 || 20471 || 20962 || 297371 || 297760
-|- align="right" style="color:gray;" |
-| align="center" style="color:black;" | ubifs/yaffs2 || style="color:green;" | 12.95 || style="color:green;" | 13.75 || 1.00 || 1.00 || 1.01 || style="color:green;" | 13.79 || 1.01 || style="color:green;" | 13.22 || 1.01 || style="color:green;" | 13.33 || style="color:green;" | 13.75 || 1.00 || 1.00
-|-
-|}
-−
-{|border="1" cellpadding="5" cellspacing="0"
-|+ align="top" | UBIFS compared to YAFFS2 (file size = 16MB)
-|-
-! 16M !! write !! rewrite !! read !! reread !! r.read !! r.write !! b.read !! r.rewrite !! s.read !! fwrite !! frewrite !! fread !! freread
-|- align="right"
-| align="center" | yaffs2 || 1538 || 1523 || 297199 || 298525 || 298896 || 1528 || 298433 || 1525 || 298847 || 1538 || 1525 || 299661 || 300656
-|- align="right"
-| align="center" | ubifs || 20501 || 20656 || 298272 || 299109 || 299032 || 20521 || 298417 || 20710 || 298923 || 20448 || 20521 || 298259 || 299267
-|- align="right" style="color:gray;" |
-| align="center" style="color:black;" | ubifs/yaffs2 || style="color:green;" | 13.33 || style="color:green;" | 13.56
-|| 1.00 || 1.00 || 1.00 || style="color:green;" | 13.43
-|| 1.00 || style="color:green;" | 13.58
-|| 1.00 || style="color:green;" | 13.30 || style="color:green;" | 13.46
-|| 1.00 || 1.00
-|-
-|}
-−
-{|border="1" cellpadding="5" cellspacing="0"
-|+ align="top" | UBIFS compared to YAFFS2 (file size = 32MB)
-|-
-! 32M !! write !! rewrite !! read !! reread !! r.read !! r.write !! b.read !! r.rewrite !! s.read !! fwrite !! frewrite !! fread !! freread
-|- align="right"
-| align="center" | yaffs2 || 1539 || 1525 || 296537 || 297204 || 297253 || 1527 || 297177 || 1527 || 296583 || 1531 || 1523 || 296537 || 297463
-|- align="right"
-| align="center" | ubifs || 20474 || 20611 || 296765 || 297490 || 297334 || 20659 || 296972 || 38416 || 297371 || 19068 || 20059 || 296618 || 296658
-|- align="right" style="color:gray;" |
-| align="center" style="color:black;" | ubifs/yaffs2 || style="color:green;" | 13.30 || style="color:green;" | 13.52
-|| 1.00 || 1.00 || 1.00 || style="color:green;" | 13.53
-|| 1.00 || style="color:green;" | 25.16
-|| 1.00 || style="color:green;" | 12.45 || style="color:green;" | 13.17
-|| 1.00 || 1.00
-|-
-|}
-−
-=== Creating UBI Image ===
-This is easiest to do, if you have access to the device and can run ubinfo and dmesg, otherwise you'll need to determine the volume size, Logical Erase Block size, etc by other means. UBI has some block overhead, which I found documentation inconsistent with my particular application, so your results may very. If your device is one UBI image for the entire NAND, this should be easier, and could probably be determined by just mounting a copy of the UBI image from the device if available.
-−
-To create the image from a rootfs you've built first you need to create the ubi.ini file, that describes your ubi image. Create a regular text file, ubi.ini, example contents, for more info run ubinize -h:
-−
- [ubi_rfs]
- mode=ubi
- image=ubifs.img
- vol_id=0
- vol_size=87349248
- vol_type=dynamic
- vol_name=ubi_rfs
- vol_alignment=1
- vol_flags=autoresize
-−
-Next you'll run the commands that actually build it. Here ubi.ini is the file you just created, ubifs.img is a temp file you can delete once you are done, and your_erootfs.ubi is the name of the rootfs image that will be created.
-−
- sudo /usr/sbin/mkfs.ubifs -m 2048 -e 129024 -c 677 -r /path/to/rootfs ubifs.img
- sudo /usr/sbin/ubinize -o your_erootfs.ubi -p 131072 -m 2048 -s 512 -O 512 ubi.ini
-−
-To determine these and the ubi.ini file settings, use ubinfo -a and dmesg on the device if possible, which both give plenty of information about the values needed. The size and vol_name are listed under "Present volumes" when you run ubinfo -a on the device. The second half of that particular ubi device's description. While the NAND description's PEB, LEB etc are in dmesg.
-−
-mkfs.ubifs
-* -m - Minimum I/O unit size.
-* -e - Logical Erase Block (LEB) size.
-* -c - Max LEB count. (vol_size/LEB)
-* -r - Path to root filesystem.
-* ubifs.img - Temporary image file.
-−
-ubinize
-* -o - Output file.
-* -p - Physical Erase Block (PEB) size.
-* -m - Minimum I/O unit size.
-* -s - Minimum I/O size for UBI headers, eg. sub-page size.
-* -O - VID header offset from start of PEB.
-* ubi.ini - UBI image configuration file.
 == YAFFS2 ==

@@ Line 88: / Line 88: @@
 http://www.linuxfordevices.com/c/a/Linux-For-Devices-Articles/Introducing-initramfs-a-new-model-for-initial-RAM-disks/
-All of the papers by Nicholas McGuire at:
+Here is a good article about how to build an initramfs:
-http://linuxdevices.com/news/NS6374541663.html
+* http://www.landley.net/writing/rootfs-howto.html
 == JFFS2 ==

@@ Line 50: / Line 50: @@
 to rotating storage media (old hard disk drives), and fullfill them.  This involves
 mapping the read and write requests to areas of the NAND flash in the chip, and managing
-the NAND flash to try to optimize correctness and longevity.  NAND flash must
+the NAND flash to try to optimize for correctness and longevity of the flash memory.  NAND flash must
 be re-written in large blocks (erase blocks) that are many times the size of individual
 file system blocks.  Therefore, the method of mapping, re-arranging and garbage collecting