The document discusses two Linux file systems: ext4 and BTRFS. Ext4 is the latest version of the ext file system family and aims to overcome limitations of ext3, such as larger file and volume sizes and improved performance. BTRFS is a newer file system that uses B-trees for its structures and aims to replace ext3/4 with new storage management approaches like snapshots and copy-on-write. The document provides details on the technical specifications and features of each file system.
OSDC 2011 | Enterprise Linux Server Filesystems by Remo RickliNETWAYS
Der Einsatz des richtigen Filesystems ist noch immer eine grundlegende Entscheidung mit großem Einfluss auf spätere Performance und Management. Mit Ext4 und BTRFS gibt es nun zwei neue Alternativen die der Erwartungshaltung bisherige Schwachstellen auszumerzen standhalten müssen. Während Ext4 bereits stable ist und den Sprung in die gängigen Enterprise Distributionen geschafft hat, steht das von Oracle BTRFS hier noch eher am Anfang. Trotz des scheinbaren Nachteils sehen vielen in BTRFS das nächste Standardfilesystem für Linux, da es im Vergleich bestehenden Limitierungen von Ext4 auflöst und als die Linux-Alternative zu ZFS gesehen wird.
Der Vortrag erläutert Architektur und Charakteristiken beider Dateisysteme, bewertet sie aus Sicht eines Systemadministrators für den Einsatz im Rechenzentrum und beschreibt mögliche Migrationspfade.
A fast file system for unix presentation by parang saraf (cs5204 VT)Parang Saraf
This is the presentation of the paper "A fast file system for unix"
In case if you need a copy of these slides feel free to contact me at parang[DOT]saraf[AT]gmail
OSDC 2011 | Enterprise Linux Server Filesystems by Remo RickliNETWAYS
Der Einsatz des richtigen Filesystems ist noch immer eine grundlegende Entscheidung mit großem Einfluss auf spätere Performance und Management. Mit Ext4 und BTRFS gibt es nun zwei neue Alternativen die der Erwartungshaltung bisherige Schwachstellen auszumerzen standhalten müssen. Während Ext4 bereits stable ist und den Sprung in die gängigen Enterprise Distributionen geschafft hat, steht das von Oracle BTRFS hier noch eher am Anfang. Trotz des scheinbaren Nachteils sehen vielen in BTRFS das nächste Standardfilesystem für Linux, da es im Vergleich bestehenden Limitierungen von Ext4 auflöst und als die Linux-Alternative zu ZFS gesehen wird.
Der Vortrag erläutert Architektur und Charakteristiken beider Dateisysteme, bewertet sie aus Sicht eines Systemadministrators für den Einsatz im Rechenzentrum und beschreibt mögliche Migrationspfade.
A fast file system for unix presentation by parang saraf (cs5204 VT)Parang Saraf
This is the presentation of the paper "A fast file system for unix"
In case if you need a copy of these slides feel free to contact me at parang[DOT]saraf[AT]gmail
unix training | unix training videos | unix course unix online training Nancy Thomas
Website : http://www.todaycourses.com
Unix & Shell Scripting Course Content :
UNIX Background:
Introduction about Operating System(OS)
Introduction to UNIX
List of UNIX vendors available in Market
Introduction to various UNIX Implementations
History of UNIX OS Evolution from 1969
Open Source (vs.) Shared source (vs.) Closed source
Is Unix Open Source software?
UNIX (vs.) LINUX
LINUX OS background
LINUX (vs.) WINDOWS
Popular LINUX distributions/Vendors
Similarities between Unix & Linux
Differences between Unix & Linux
About POSIX standards
UNIX System architecture:
Hardware
Kernel
Shell
Utilities and User programs
Layers in Unix OS
Unix Servers/Dumb terminals/nodes
UNIX System features:
Multitasking
Multiuser
Easy Portability
Security
Communication
UNIX day-to-day used commands:
System Information commands (uname, date, etc)
man command
User Related (w, who, etc)
Terminal Related (stty, etc)
Filter commands (more, less, etc)
Miscellaneous commands (cal, banner, clear, etc)
Viewing exit status of commands
Disk Related commands
unix training, unix training videos, unix training topics, unix online training,unix classes online, unix training online, free unix training, unix courses, learn unix online, unix certification, unix course, learning linux, how to learn linux, linux training, red hat linux, how to linux, unix shell scripting, unix shell (software), unix shell scripting tutorial for beginners, unix shell scripting tutorial, unix (software), unix training in pune, unix training in hyderabad, unix training in pune
A presentation on the Ext4 file system and the evolution of Ext filesystem in Linux operating system. Linux uses virtual filesystem. The comparison of the ext filesystem generations is provided.
LAS16-400: Mini Conference 3 AOSP (Session 1)Linaro
LAS16-400: Mini Conference 3 AOSP (Session 1)
Speakers: Thomas Gall, Bernhard Rosenkränzer
Date: September 29, 2016
★ Session Description ★
The Android Open Source Project is one community which is strategic to Linaro and it’s members. The purpose of this mini conference is to gather fellow Android engineers together from the community, member companies, and Linaro to discuss engineering activities and improve collaboration across different groups.
Within this mini conference we encourage discussion and presentations to advance engineering topics, forge consensus and educate each other.
The tentative agenda for this mini conference includes :
- Quick introduction
- Filesystems - Between requirements for encryption and standing concerns about degrading performance as an Android file system age, let’s have some discussion involving current data, known issues and towards improvements in this area for Android.
- HAL consolidation - Review current status and discuss next steps to work on.
One build for many devices: device/build configuration. Next features and platforms to add. Gaps in HiKey support vs. AOSP build.
- Graphics - YUV support in mesa and hwc.
- WiFi and sensor HAL status and next steps
- New developments with AOSP + the Kernel - With regards to the Google Common Kernel tree and upstream Linux kernel activities related to Android, there are a few topics up for discussion:
- - Updates on HiKey in AOSP
- - EAS in common.git & integration with AOSP userspace
- - New Sync API in 4.6+ kernels, and how it will affects graphics drivers
- AOSP transition to clang - As everyone knows GCC in AOSP has been deprecated. Let’s cover current status, issues and next steps. Let’s also discuss the elephant in the room, building the kernel with clang.
- Out of tree AOSP User space Patches - This is a discussion with the goal of organized action to see forward progress on AOSP user space patches that aren’t in AOSP for whatever reason.
- Android is used in some environments where booting can be frequent and affect the product experience. Do you want to wait for a minute while your car boots? We’ll spend time brainstorming on improving Android boot time.
★ Resources ★
Etherpad: pad.linaro.org/p/las16-400
Presentations & Videos: http://connect.linaro.org/resource/las16/las16-400/
★ Event Details ★
Linaro Connect Las Vegas 2016 – #LAS16
September 26-30, 2016
http://www.linaro.org
http://connect.linaro.org
unix training | unix training videos | unix course unix online training Nancy Thomas
Website : http://www.todaycourses.com
Unix & Shell Scripting Course Content :
UNIX Background:
Introduction about Operating System(OS)
Introduction to UNIX
List of UNIX vendors available in Market
Introduction to various UNIX Implementations
History of UNIX OS Evolution from 1969
Open Source (vs.) Shared source (vs.) Closed source
Is Unix Open Source software?
UNIX (vs.) LINUX
LINUX OS background
LINUX (vs.) WINDOWS
Popular LINUX distributions/Vendors
Similarities between Unix & Linux
Differences between Unix & Linux
About POSIX standards
UNIX System architecture:
Hardware
Kernel
Shell
Utilities and User programs
Layers in Unix OS
Unix Servers/Dumb terminals/nodes
UNIX System features:
Multitasking
Multiuser
Easy Portability
Security
Communication
UNIX day-to-day used commands:
System Information commands (uname, date, etc)
man command
User Related (w, who, etc)
Terminal Related (stty, etc)
Filter commands (more, less, etc)
Miscellaneous commands (cal, banner, clear, etc)
Viewing exit status of commands
Disk Related commands
unix training, unix training videos, unix training topics, unix online training,unix classes online, unix training online, free unix training, unix courses, learn unix online, unix certification, unix course, learning linux, how to learn linux, linux training, red hat linux, how to linux, unix shell scripting, unix shell (software), unix shell scripting tutorial for beginners, unix shell scripting tutorial, unix (software), unix training in pune, unix training in hyderabad, unix training in pune
A presentation on the Ext4 file system and the evolution of Ext filesystem in Linux operating system. Linux uses virtual filesystem. The comparison of the ext filesystem generations is provided.
LAS16-400: Mini Conference 3 AOSP (Session 1)Linaro
LAS16-400: Mini Conference 3 AOSP (Session 1)
Speakers: Thomas Gall, Bernhard Rosenkränzer
Date: September 29, 2016
★ Session Description ★
The Android Open Source Project is one community which is strategic to Linaro and it’s members. The purpose of this mini conference is to gather fellow Android engineers together from the community, member companies, and Linaro to discuss engineering activities and improve collaboration across different groups.
Within this mini conference we encourage discussion and presentations to advance engineering topics, forge consensus and educate each other.
The tentative agenda for this mini conference includes :
- Quick introduction
- Filesystems - Between requirements for encryption and standing concerns about degrading performance as an Android file system age, let’s have some discussion involving current data, known issues and towards improvements in this area for Android.
- HAL consolidation - Review current status and discuss next steps to work on.
One build for many devices: device/build configuration. Next features and platforms to add. Gaps in HiKey support vs. AOSP build.
- Graphics - YUV support in mesa and hwc.
- WiFi and sensor HAL status and next steps
- New developments with AOSP + the Kernel - With regards to the Google Common Kernel tree and upstream Linux kernel activities related to Android, there are a few topics up for discussion:
- - Updates on HiKey in AOSP
- - EAS in common.git & integration with AOSP userspace
- - New Sync API in 4.6+ kernels, and how it will affects graphics drivers
- AOSP transition to clang - As everyone knows GCC in AOSP has been deprecated. Let’s cover current status, issues and next steps. Let’s also discuss the elephant in the room, building the kernel with clang.
- Out of tree AOSP User space Patches - This is a discussion with the goal of organized action to see forward progress on AOSP user space patches that aren’t in AOSP for whatever reason.
- Android is used in some environments where booting can be frequent and affect the product experience. Do you want to wait for a minute while your car boots? We’ll spend time brainstorming on improving Android boot time.
★ Resources ★
Etherpad: pad.linaro.org/p/las16-400
Presentations & Videos: http://connect.linaro.org/resource/las16/las16-400/
★ Event Details ★
Linaro Connect Las Vegas 2016 – #LAS16
September 26-30, 2016
http://www.linaro.org
http://connect.linaro.org
Case study of BtrFS: A fault tolerant File systemKumar Amit Mehta
A case study of Fault Tolerance features of BTRFS. These slides were prepared for the coursework for a Masters level program at Tallinn University of Technology, Estonia. A lot of materials in the slides are taken from the materials in the public domain. Many thanks to the people on BTRFS IRC Channel.
It is the File system that is contained on the same partition on which the "Root directory" is located. It is the File system on which all the other file systems are mounted
Daniel Phillips, Senior Linux Kernel Engineer from the Samsung OSG, discusses a new general purpose filesystem for Linux (Tux3) that he's been working on to address performance and scalability for both spinning storage and SSD's.
Smart TV Buyer Insights Survey 2024 by 91mobiles.pdf91mobiles
91mobiles recently conducted a Smart TV Buyer Insights Survey in which we asked over 3,000 respondents about the TV they own, aspects they look at on a new TV, and their TV buying preferences.
Dev Dives: Train smarter, not harder – active learning and UiPath LLMs for do...UiPathCommunity
💥 Speed, accuracy, and scaling – discover the superpowers of GenAI in action with UiPath Document Understanding and Communications Mining™:
See how to accelerate model training and optimize model performance with active learning
Learn about the latest enhancements to out-of-the-box document processing – with little to no training required
Get an exclusive demo of the new family of UiPath LLMs – GenAI models specialized for processing different types of documents and messages
This is a hands-on session specifically designed for automation developers and AI enthusiasts seeking to enhance their knowledge in leveraging the latest intelligent document processing capabilities offered by UiPath.
Speakers:
👨🏫 Andras Palfi, Senior Product Manager, UiPath
👩🏫 Lenka Dulovicova, Product Program Manager, UiPath
Essentials of Automations: The Art of Triggers and Actions in FMESafe Software
In this second installment of our Essentials of Automations webinar series, we’ll explore the landscape of triggers and actions, guiding you through the nuances of authoring and adapting workspaces for seamless automations. Gain an understanding of the full spectrum of triggers and actions available in FME, empowering you to enhance your workspaces for efficient automation.
We’ll kick things off by showcasing the most commonly used event-based triggers, introducing you to various automation workflows like manual triggers, schedules, directory watchers, and more. Plus, see how these elements play out in real scenarios.
Whether you’re tweaking your current setup or building from the ground up, this session will arm you with the tools and insights needed to transform your FME usage into a powerhouse of productivity. Join us to discover effective strategies that simplify complex processes, enhancing your productivity and transforming your data management practices with FME. Let’s turn complexity into clarity and make your workspaces work wonders!
DevOps and Testing slides at DASA ConnectKari Kakkonen
My and Rik Marselis slides at 30.5.2024 DASA Connect conference. We discuss about what is testing, then what is agile testing and finally what is Testing in DevOps. Finally we had lovely workshop with the participants trying to find out different ways to think about quality and testing in different parts of the DevOps infinity loop.
Transcript: Selling digital books in 2024: Insights from industry leaders - T...BookNet Canada
The publishing industry has been selling digital audiobooks and ebooks for over a decade and has found its groove. What’s changed? What has stayed the same? Where do we go from here? Join a group of leading sales peers from across the industry for a conversation about the lessons learned since the popularization of digital books, best practices, digital book supply chain management, and more.
Link to video recording: https://bnctechforum.ca/sessions/selling-digital-books-in-2024-insights-from-industry-leaders/
Presented by BookNet Canada on May 28, 2024, with support from the Department of Canadian Heritage.
Accelerate your Kubernetes clusters with Varnish CachingThijs Feryn
A presentation about the usage and availability of Varnish on Kubernetes. This talk explores the capabilities of Varnish caching and shows how to use the Varnish Helm chart to deploy it to Kubernetes.
This presentation was delivered at K8SUG Singapore. See https://feryn.eu/presentations/accelerate-your-kubernetes-clusters-with-varnish-caching-k8sug-singapore-28-2024 for more details.
Removing Uninteresting Bytes in Software FuzzingAftab Hussain
Imagine a world where software fuzzing, the process of mutating bytes in test seeds to uncover hidden and erroneous program behaviors, becomes faster and more effective. A lot depends on the initial seeds, which can significantly dictate the trajectory of a fuzzing campaign, particularly in terms of how long it takes to uncover interesting behaviour in your code. We introduce DIAR, a technique designed to speedup fuzzing campaigns by pinpointing and eliminating those uninteresting bytes in the seeds. Picture this: instead of wasting valuable resources on meaningless mutations in large, bloated seeds, DIAR removes the unnecessary bytes, streamlining the entire process.
In this work, we equipped AFL, a popular fuzzer, with DIAR and examined two critical Linux libraries -- Libxml's xmllint, a tool for parsing xml documents, and Binutil's readelf, an essential debugging and security analysis command-line tool used to display detailed information about ELF (Executable and Linkable Format). Our preliminary results show that AFL+DIAR does not only discover new paths more quickly but also achieves higher coverage overall. This work thus showcases how starting with lean and optimized seeds can lead to faster, more comprehensive fuzzing campaigns -- and DIAR helps you find such seeds.
- These are slides of the talk given at IEEE International Conference on Software Testing Verification and Validation Workshop, ICSTW 2022.
Generative AI Deep Dive: Advancing from Proof of Concept to ProductionAggregage
Join Maher Hanafi, VP of Engineering at Betterworks, in this new session where he'll share a practical framework to transform Gen AI prototypes into impactful products! He'll delve into the complexities of data collection and management, model selection and optimization, and ensuring security, scalability, and responsible use.
zkStudyClub - Reef: Fast Succinct Non-Interactive Zero-Knowledge Regex ProofsAlex Pruden
This paper presents Reef, a system for generating publicly verifiable succinct non-interactive zero-knowledge proofs that a committed document matches or does not match a regular expression. We describe applications such as proving the strength of passwords, the provenance of email despite redactions, the validity of oblivious DNS queries, and the existence of mutations in DNA. Reef supports the Perl Compatible Regular Expression syntax, including wildcards, alternation, ranges, capture groups, Kleene star, negations, and lookarounds. Reef introduces a new type of automata, Skipping Alternating Finite Automata (SAFA), that skips irrelevant parts of a document when producing proofs without undermining soundness, and instantiates SAFA with a lookup argument. Our experimental evaluation confirms that Reef can generate proofs for documents with 32M characters; the proofs are small and cheap to verify (under a second).
Paper: https://eprint.iacr.org/2023/1886
Le nuove frontiere dell'AI nell'RPA con UiPath Autopilot™UiPathCommunity
In questo evento online gratuito, organizzato dalla Community Italiana di UiPath, potrai esplorare le nuove funzionalità di Autopilot, il tool che integra l'Intelligenza Artificiale nei processi di sviluppo e utilizzo delle Automazioni.
📕 Vedremo insieme alcuni esempi dell'utilizzo di Autopilot in diversi tool della Suite UiPath:
Autopilot per Studio Web
Autopilot per Studio
Autopilot per Apps
Clipboard AI
GenAI applicata alla Document Understanding
👨🏫👨💻 Speakers:
Stefano Negro, UiPath MVPx3, RPA Tech Lead @ BSP Consultant
Flavio Martinelli, UiPath MVP 2023, Technical Account Manager @UiPath
Andrei Tasca, RPA Solutions Team Lead @NTT Data
GraphRAG is All You need? LLM & Knowledge GraphGuy Korland
Guy Korland, CEO and Co-founder of FalkorDB, will review two articles on the integration of language models with knowledge graphs.
1. Unifying Large Language Models and Knowledge Graphs: A Roadmap.
https://arxiv.org/abs/2306.08302
2. Microsoft Research's GraphRAG paper and a review paper on various uses of knowledge graphs:
https://www.microsoft.com/en-us/research/blog/graphrag-unlocking-llm-discovery-on-narrative-private-data/
Why You Should Replace Windows 11 with Nitrux Linux 3.5.0 for enhanced perfor...SOFTTECHHUB
The choice of an operating system plays a pivotal role in shaping our computing experience. For decades, Microsoft's Windows has dominated the market, offering a familiar and widely adopted platform for personal and professional use. However, as technological advancements continue to push the boundaries of innovation, alternative operating systems have emerged, challenging the status quo and offering users a fresh perspective on computing.
One such alternative that has garnered significant attention and acclaim is Nitrux Linux 3.5.0, a sleek, powerful, and user-friendly Linux distribution that promises to redefine the way we interact with our devices. With its focus on performance, security, and customization, Nitrux Linux presents a compelling case for those seeking to break free from the constraints of proprietary software and embrace the freedom and flexibility of open-source computing.
Enhancing Performance with Globus and the Science DMZGlobus
ESnet has led the way in helping national facilities—and many other institutions in the research community—configure Science DMZs and troubleshoot network issues to maximize data transfer performance. In this talk we will present a summary of approaches and tips for getting the most out of your network infrastructure using Globus Connect Server.
2. Agenda
● Introduction/motivation
● ext4 – the new member of the extfs family
● Facts, specs
● Migration
● BTRFS – the newbie .. the hope
● Facts, specs
● Migration
● Summary
OSDC 2011 2
3. Linux file systems
● More than 50 file systems shipped with Linux
kernel
● Local
● Remote
● Cluster
● ...
● A few as standard for root directory
● ext2, ext3
● XFS
OSDC 2011 3
4. Linux file systems – challenges
● ReiserFS sun-setted
● Limitations of ext3
● Changes in recent Enterprise distributions
OSDC 2011 4
5. Linux file systems – new players
● New version of the ext family -> ext4
● Marked as stable
● Shipped with Enterprise distributions
● New approach with BTRFS
● Still experimental
● Default by some projects, e.g. MeeGo
OSDC 2011 5
6. th
4 extended file system
● Shipped since 2.6.19
● Stable since 2.6.28
● To overcome limits of ext3
● Size
● Performance
OSDC 2011 6
7. Ext4 - history
● Successor of ext3
● Started as set of patches for ext3
● Later forked
● First called ext3dev (sometimes ext4dev)
● Not impact ext3 stability
● Less dependencies to ext3 code
● Easier to maintain source code
OSDC 2011 7
8. Ext4 - facts
● Max volume size: 1 EByte = 1024 PByte
● Max file size: 16 TByte
● Max length of file name: 256 Bytes
● Support of extended attributes
● No encryption
● Not really compression
● Partially 64bit
OSDC 2011 8
9. Ext4 – starting from known
● Known tools
● mkfs
● fsck
● tune2fs
● e2label
OSDC 2011 9
10. Ext4 – global structure I
● Entry point -> superblock
● Block size
● Number of blocks and inodes
● Number of free blocks and inodes
● Disk divided in block groups
● backup of superblock
● Block group description (inode/block bitmaps)
OSDC 2011 10
11. Ext4 – global structure II
● Similar to ext3
● Inherits some ext3 limitations
● Number of inodes per block group
●
2nd type of block groups => flexible
● Flexible placement of bitmaps
● Bigger inodes to store additional information
● 256 Bytes
● Nano second time stamps
OSDC 2011 11
12. Ext4 – from blocks to extents
● Common addressing for modern file systems
● Contiguous area of blocks
● Less management information needed
● Less meta data operations
● Less “fragmentation”
● Requires change of on-disk format
OSDC 2011 12
13. Ext4 – extent I
● 15 bit for extent size
● Block size of 4 KByte => 128 MByte
● 1 bit for extent initialization information
struct ext4_extent {
__le32 ee_block; /* first logical block extent covers */
__le16 ee_len; /* number of blocks covered by extent */
__le16 ee_start_hi; /* high 16 bits of physical block */
__le32 ee_start_lo; /* low 32 bits of physical block */
};
OSDC 2011 13
14. Ext4 – extent II
● 32 bit for block addresses inside file
● Block size of 4 KByte => 16 TByte
● 48 (!) bit for block addresses of file system
● Block size of 4 KByte => 1 EByte
OSDC 2011 14
15. Ext4 – extent III
● 60 Byte for extent information
● 12 Byte for extent header
● 12 Byte for extent structure
– Up to 4 extents per inode
– max. 512 MByte direct addressable (ext3: 48 KByte)
– Different schema for bigger files
OSDC 2011 15
16. Ext4 – extent tree I
● For files > 512 MByte
● B+ tree
● Extent structure only at leaf nodes
● New element: extent index
● Same header structure like data extent
● Points to data block
● Data block contains either extent index or extent
structure
OSDC 2011 16
18. Ext4 – from extents to blocks
● At the end block allocation
● New features
● Multi-block allocation
● Delayed allocation
● Persistent allocation
OSDC 2011 18
19. Ext4 – multi-block allocation
● Ext3: only one block
● 12800 calls for 50 MByte file
● Ext4: multiple blocks per call
● Less overhead
● Contiguous physical location of data
OSDC 2011 19
20. Ext4 – delayed allocation
● Ext3
● Instant block allocation
● Fragmentation due to buffers and caches
● Ext4
● Delayed block allocation
● Use cache information for placement
● Risk of data loss in early versions => improved
since 2.6.30
OSDC 2011 20
21. Ext4 – “clever” allocation
● Support of system call fallocate()
● Application reserves blocks ahead
● File system ensures disk space availability
● Allocation information in extent structure
●
Remember 16th bit
OSDC 2011 21
22. Ext4 – consistent status
● New journaling => JBD2
● Transactions have checksums
● 64 bit ready
● Deactivation possible
OSDC 2011 22
23. Ext4 – repair
● Improved fsck()
● No check of unused blocks
– information stored in block group header
– Information secured via checksums
– (de)activation possible at any time
● First run as slow like in ext3
OSDC 2011 23
24. Ext4 – other news
● Nano second precision time stamps
● Unix millennium bug shifted to 2514
● More subdirectories
● Up to 65000
● More than 65000 ... with limitation
OSDC 2011 24
25. Ext4 – general migration paths
● mkfs() and backup/restore
● Clean new file system structure
● Only way for file systems other than ext2/3
● Extended outage
● Conversion via tune2fs
● Partial only
● Only possible for ext family
● Faster/easier
OSDC 2011 25
26. Ext4 – background for migration
● 2 kind of changes compared to ext3
● change of ondisk format:
– Extents
– Only enabled for new files via tune2fs
– Additional tasks needed
● Ondisk format not relevant
– block allocation
– Immediately enabled via tune2fs
OSDC 2011 26
27. Ext4 – migration via tune2fs
● Results in mix of ext3 and ext4 structure
● Access via ext3 driver impossible
● fsck() needed
parameter description
extent Extent based block allocation
flex_bg Flexible placement of meta data
uninit_bg Flag uninitialized blocks for faster fsck
dir_nlink Infinite number of sub directories
extra_isize Timestamps with nano seconds
OSDC 2011 27
28. Ext4 – migration hints
● fsck() recommended
● /boot – booting from ext4 possible?
● Rescue media enabled for ext4?
OSDC 2011 28
29. Ext4 – summary
● Good successor of ext3
● Manages higher amount of data
● Faster
● Performance
● recovery
● Safer
● Sufficient migration options from ext2/3
OSDC 2011 29
30. Better/b-tree file system
● Shipped since 2.6.29
● Still experimental
● Replace ext3/4
● New storage management approach
OSDC 2011 30
31. BTRFS - history
● Basic idea
● Shown 2007
● Usage of B trees for standard structures
● Not new ... see XFS, ReiserFS
● Chris Mason
● Worked on ReiserFS for SUSE
● Moved to Oracle -> started BTRFS developement
OSDC 2011 31
32. BTRFS - facts
● Max file/volume size: 16 EByte
● Max length of file name: 256 Bytes
● Support of
● Extended attributes
● Encryption
● Compression
● Snapshot
● Copy-on-Write
OSDC 2011 32
33. BTRFS – global structure
● Entry point -> superblock
● More than one file system per volume
● Extents
● Put together in block groups
● No mix of data and meta data
OSDC 2011 33
34. BTRFS – internals: the trees
● Consists of B+ trees
● Root tree
● File system tree
● Extent allocation tree
● Checksum tree
● Log tree
● Chunk & device tree
● Data relocation tree
OSDC 2011 34
35. BTRFS – internals: structures
● 3 structures
● Key
– index of the tree structure
● Block header
– ID of file system
– Reference of insert time
– Level position
● Item
– Different types: inodes, extents, directories
OSDC 2011 35
36. BTRFS – internals: the key
● Index of the tree structure
● Size: 136 bit
● First 64 bit: unique object ID
● Next 8 bit: type/item
● Last 64 bit: item dependent
● e.g. Hash of directory name
● e.g. Number of elements in directory
● e.g. object ID of upper layer directory
OSDC 2011 36
37. BTRFS – internals: the item
● More than one item per object ID possible
Item Value
INODE_ITEM 1
XATTR_ITEM 24
DIR_ITEM 84
DIR_INDEX 96
EXTENT_DATA 108
EXTENT_CSUM 128
ROOT_ITEM 132
EXTENT_ITEM 168
OSDC 2011 37
38. BTRFS – more about trees
● Highest layer
● Root tree
● Referenced in superblock
● Other trees => object ID in root tree
● Some trees unique
● Extent allocation
● Data relocation
● Possibly multiple trees
● File system
OSDC 2011 38
39. BTRFS – file system tree
● Visible part
● Contains:
● Inode items
● Reference items
● No data of files
● See extents
● Exception: small files
OSDC 2011 39
40. BTRFS – extent allocation tree
● Space management
● Backward reference
● file system object
● Possibly multiple per extent
● Maybe move to extent data reference object
OSDC 2011 40
41. BTRFS – other trees
● Log tree
● Collects fsync() calls
● Journal of this kind of COW calls
● Checksum tree
● CRC32 checksums of data and meta data
● Chunk tree
● Manage devices: device item and chunk map item
● Device tree
● Counterpart of chunk tree
OSDC 2011 41
42. BTRFS – device management
● Included volume manager
● pool concept
● RAID-0 and RAID-1
● For data and meta data
● Not necessarily identical
● Chunk tree
● abstract from disk block
OSDC 2011 42
44. BTRFS – what else
● Transparent compression via zlib
● Support of POSIX ACL's
● Online grow/shrink
● Online add/removal of disks
● No fsck() tool (yet)
● Management tool evolution (btrfsctl -> btrfs)
OSDC 2011 44
45. BTRFS – migration I
● Via tool btrfs-convert
● du/df not fully BTRFS-aware
● In place from ext3/4
● Via libe2fs
● BTRFS meta data location flexible
● Old ext3/4 organized in snapshot
● Roll-back possible to date/time of conversion
OSDC 2011 45
47. BTRFS summary
● Still experimental
● Meets standard file systems requirements
● Bridges existing gaps
● e.g. snapshots
● easy migration from ext3/4 possible
● New approach to storage management
● e.g. included volume manager
OSDC 2011 47
48. Summary
● Improvement moving to ext4
● Safe switching to ext4
● In place migration from ext3 possible
● Future is BTRFS
● In place migration from ext3/4 to BTRFS
possible
OSDC 2011 48