File system is divided in two segments called User Data and Metadata. In this article I am trying to explore how to create and convert various Linux file systems and high level difference amongst Ext2, Ext3 and Ext4 file systems. Before moving further readings, let me introduce a brief about Linux file systems.

Ext2 – Second Extended File System

1. Ext2 file system was introduced in 1993 and Ext2 was developed by Remy Card. It was the first default file system in several Linux distro like RedHat and Debian.
2. It was to overcome limitation of legacy Ext file system.
3. Maximum file size is 16GB – 2TB.
4. Journaling feature is not available.
5. It’s being used for normally Flash based storage media like USB Flash drive, SD Card etc.

Ext3 – Third Extended File System

1. Ext3 file system was introduced in 2001 and same was integrated in Kernel 2.4.15 with journaling feature, which is to improve reliability and eliminates need to check file system after unclean shutdown.
2. Max file size 16GB – 2TB.
3. Provide facility to upgrade from Ext2 to Ext3 file systems without having to back up and restore data.

Ext4 – Fourth Extended File System

1. Ext4, the high-anticipated Ext3 successor.
2. On October 2008, Ext4 as stable code were merged in the Kernel 2.6.28 which contains Ext4 file system.
3. Backward compatibility.
4. Max file size 16GB to 16TB.
5. Ext4 file system have option to Turn Off journaling feature.
6. Other features like Sub Directory Scalability, Multiblock Allocation, Delayed Allocation, Fast FSCK etc.

So two weeks have passed, and the merge window for 4.19 is over.

This was a fairly frustrating merge window, artly because 4.19 looks to be a pretty big release (no single reason), and partly just due to random noise. We had the L1TF hw vulnerability disclosure early in the merge window, which just added the usual frustration due to having patches that weren't public. That just shows just how good all our infrastructure for linux-next and various automated testing systems have become, in how painful it is when it's lacking.

Linus Torvalds

TORONTO — It’s been twenty-five years since Linux began. Today, we’re living in a world where Microsoft has embraced Linux and everything — and I mean everything — depends on Linux. It didn’t start that way. It began as a small project without any great ambitions.

LTS Linux will now have a six-year life, rather than a two-year life, which is just what Android developers want and what Android users need.

Things were quite calm this week, so I really didn’t have any real
reason to delay the 4.12 release.

As mentioned over the various rc announcements, 4.12 is one of the
bigger releases historically, and I think only 4.9 ends up having had
more commits. And 4.9 was big at least partly because Greg announced
it was an LTS kernel. But 4.12 is just plain big.

There’s also nothing particularly odd going on in the tree – it’s all
just normal development, just more of it that usual. The shortlog
below is obviously just the minor changes since rc7 – the whole 4.12
shortlog is much too large to post.

In the diff department, 4.12 is also very big, although the reason
there isn’t just that there’s a lot of development, we have the added
bulk of a lot of new header files for the AMD Vega support. That’s
almost exactly half the bulk of the patch, in fact, and partly as a
result of that the driver side dominates everything else at 85+% of
the release patch (it’s not all the AMD Vega headers – the Intel IPU
driver in staging is big too, for example).

But aside from just being large, and a blip in size around rc5, the
rc’s stabilized pretty nicely, so I think we’re all good to go.

Go out and use it.

Oh, and obviously this means that the merge window for 4.13 is thus
open. You know the drill.

Linus

In the latest Top500 supercomputer race, only two — count ‘em, two — of the world’s fastest computers aren’t running Linux.

June 2017

In the latest rankings, the Sunway TaihuLight, a system developed by China’s National Research Center of Parallel Computer Engineering & Technology (NRCPC) and installed at the National Supercomputing Center in Wuxi, maintains its top position. With a Linpack performance of 93 petaflops, TaihuLight is far and away the most powerful number-cruncher on the planet.

Tianhe-2, (Milky Way-2), a system developed by China’s National University of Defense Technology (NUDT) and deployed at the National Supercomputer Center in Guangzho, China, occupies the number two position with a Linpack mark of 33.9 petaflops. Tianhe-2 was the number one system in the TOP500 list for three consecutive years, until TaihuLight eclipsed it in June 2016.

The new number three supercomputer is the upgraded Piz Daint, a Cray XC50 system installed at the Swiss National Supercomputing Centre (CSCS). The upgrade was accomplished with additional NVIDIA Tesla P100 GPUs, doubling the Linpack performance of the system’s previous mark of 9.8 petaflops in November 2016, which itself was the result of a significant upgrade. Piz Daint’s current Linpack result of 19.6 petaflops enabled the system to climb five positions in the rankings.

As a result of the Piz Daint upgrade, Titan, a Cray XK7 system installed at the Department of Energy’s (DOE) Oak Ridge National Laboratory, drops to number four in the rankings. Its Linpack mark of 17.6 petaflops has remained constant since it was installed in 2012.

Rounding out the top 10 are:

Sequoia (17.2 petaflops), an IBM BlueGene/Q system installed at the DOE’s Lawrence Livermore National Laboratory, at number five;
Cori (14.0 petaflops), a Cray XC40 system housed at the National Energy Research Scientific Computing Center (NERSC), at number six;
Oakforest-PACS (13.6 petaflops), a Fujitsu PRIMERGY system running at Japan’s Joint Center for Advanced High Performance Computing, at number seven;
Fujitsu’s K computer (10.5 petaflops), installed at the RIKEN Advanced Institute for Computational Science (AICS), at number eight;
Mira (8,6 petaflops), an IBM BlueGene/Q system installed at DOE’s Argonne National Laboratory, at number nine; and
Trinity (8.1 petaflops), a Cray XC40 system running at Los Alamos National Laboratory, at number ten.

With the two Chinese supercomputers and one Swiss system occupying the top of the rankings, this is the second time in the 24-year history of the TOP500 list that the United States has failed to secure any of the top three positions. The only other time this occurred was in November 1996, when three Japanese systems captured the top three spots.

Linus Torvalds took to the stage in China for the first time Monday at LinuxCon + ContainerCon + CloudOpen China in Beijing. In front of a crowd of nearly 2,000, Torvalds spoke with VMware Head of Open Source Dirk Hohndel in one of their famous “fireside chats” about what motivates and surprises him and how aspiring open source developers can get started. Here are some highlights of their talk.

Samba è la collezione di server open source per condividere in rete file e cartelle nello standard Microsoft.

Samba per lavorare bene, ovvero rispondere prontamente alle richieste dei computer in rete, richiede una buona dotazione di CPU. Per piccole condivisioni si possono usare CPU come le attuali ARM a 32 bit e sul GHz.

Ma per permettere agli utenti di rete di utilizzare i loro preferiti programmi d’ufficio senza anomalie, è necessario usare CPU molto più prestanti. Infatti l’inadeguata risorsa CPU può portare ad effetti quali problemi con le molteplici aperture di file *.DOC che l’utente normale esegue senza ritegno. L’apertura in rete di questi file è di una buona complessità per il lock che vengono fatti, in particolare possono emergere problematiche indotte da mal funzionamenti del programma lato utente.

Purtroppo i “NAS” in commercio, anche i più costosi, in genere usano CPU di fascia bassa. Quindi sono da concepiere per utilizzi personali o backup.

La soluzione ottimale è l’installazione di Ubuntu Server o Centos, conforme Red Hat,  su un hardware adeguato, per esempio un sistema con CPU Fx  sui 4 GHz con 8 core, oppure un server con CPU Opteron 12 core tipo HP Proliant Gen8.

Per chi ritenga inaccessibili queste tecnologie può utilizzare FreeNAS, che è un’ottima soluzione open source per installare e configurare facilmente il proprio server Samba su un hardware adeguato, per esempio un buon computer desktop.

Tra le ultime caratteristiche di FreeNAS segnaliamo il supporto ZFS.

La prossima versione 3.9 del kernel avrà alcuni aggiornamenti nella gestione EXT4.

Aggiungerà la gestione RAID 5/6 per Btrfs, aprendo così il supporto sperimentale al RAID 5 e RAID 6.

Il file system XFS avrà degli aggiornamenti minori.

Samsung apporta delle correzioni a F2FS, che è il nuovo “Flash Friendly File-System” introdotto da Samsung nel kernel Linux 3.8 ed ha già mostrato dei risultati molto promettenti con USB flash driver, SDHC storage ed periferiche simili.

Sarà nostro impegno eseguire test comparativi per F2FS utilizzando l’usuale piattaforma AMD FX-8320 Bulldozer con Ubuntu 13.04.