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Sunday, August 04th, 2013 | Author:

History

Much had changed since I last mentioned my personal server – Ĝi kreskis de saltegoj kaj saltegoj (it now has a 7TB md RAID6) and it had recently been rebuilt with Ubuntu Server.

Arch was never a mistake. Arch Linux had already taught me so much about Linux (Kaj daŭros tiel fari sur mia alia surtabla). But Arch definitely requires more time and attention than I would like to spend on a server. Ideally I’d prefer to be able to forget about the server for a while until a reminder email saysumthere’s a couple updates you should look at, buddy.

Space isn’t freeand neither is space

The opportunity to migrate to Ubuntu was the fact that I had run out of SATA ports, the ports required to connect hard drives to the rest of the computerthat 7TB RAID array uses a lot of ports! I had even given away my very old 200GB hard disk as it took up one of those ports. I also warned the recipient that the disk’s SMART monitoring indicated it was unreliable. Kiel intertempa workaround al la manko de SATAaj havenoj, I had even migrated the server’s OS to a set of four USB sticks in an md RAID1. Freneza. Mi scias. Mi wasn’t tro feliĉa pri la rapido. I decided to go out and buy a new reliable hard drive and a SATA expansion card to go with it.

The server’s primary Arch partition was using about 7GB of disk. A big chunk of that was a swap file, Cached datumo and otherwise miscellaneous or unnecessary files. Entute la reala grandeco de la OS, including the /home folder, Estis nur pri 2GB. This prompted me to look into a super-fast SSD drive, thinking perhaps a smaller one might not be so expensive. It turned out that the cheapest non-SSD drive I could find actually cost Pli Ol unu el ĉi tiuj relative malgranda SSDs. Yay for me. 🙂

Choice? Woah?!

En elektanta la OS, I’d jam decidis ĝin wouldn’t esti Arkaĵo. Ekstere de ĉiuj la aliaj popularaj disdonadoj, I’m most familiar with Ubuntu and CentOS. Fedora was also a possibilitybut I hadn’t seriously yet considered it for a server. Ubuntu won the round.

The next decision I had to make didn’t occur to me until Ubiquity (Ubuntu’s instalaĵa sorĉisto) Demandis ĝin de mi: How to set up the partitions.

I was new to using SSDs in Linux – I’m bone konscia de la enfaliloj de ne uzanta ilin ĝuste, Plejparte pro ilia risko de malriĉa longevity se misuzita.

Mi didn’t deziras uzi diligentan interŝanĝan septon. Mi planas sur altgradiganta la servilon’s motherboard/CPUa/memoro ne tro ege en la estonteco. Bazita sur kiu mi decidis min metos interŝanĝon en interŝanĝa dosiero sur la ekzistanta md TRUDENIRO. The swap won’t be particularly fast but its only purpose will be for that rare occasion when something’s gone wrong and the memory isn’t available.

This then left me to give the root path the full 60GB out of an Intel 330 SSD. Mi konsideris apartiganta /hejmon sed ĝi nur ŝajnita malgranda sencela, Donita kiom malmulte estis uzita en la pasinteco. I first set up the partition with LVMsomething I’ve recently been doing whenever I set up a Linux box (really, there’s no excuse not to use LVM). Kiam ĝi akiris al la parto kie mi formus la filesystem, Mi klakis la falon-malsupren kaj instinkte elektita ext4. Tiam mi rimarkis btrfs en la sama listo. Pendi sur!!

But a what?

Btrfs (“Butero-eff-ess”, “Pli bona-eff-ess”, “Abelo-arbo-eff-ess”, Aŭ kio ajn vi fantazias sur la tago) Estas relative nova filesystem evoluigita por alporti Linukson’ Filesystem kapabloj reen sur vojeto kun fluo filesystem tech. La ekzistanta King-de-la-Monteto filesystem, “Ext” (La nuna versio vokis ext4) Estas sufiĉe bona – but it is limited, stuck in an old paradigm (think of a brand new F22 Raptor vs. an F4 Phantom with a half-jested attempt at an equivalency upgrade) and is unlikely to be able to compete for very long with newer Enterprise filesystems such as Oracle’s ZFS. Btrfs ankoraŭ havas longan vojon iri kaj estas ankoraŭ konsiderita eksperimentan (Dependanta sur kiu vi demandas kaj kio prezentas vin bezono). Multaj konsideri ĝin esti stabila por baza uzo – Sed neniu estas iranta fari ajnajn garantiojn. Kaj, Nature, Ĉiu estas diranta fari kaj testaj rezervoj!

Mooooooo

La plej fundamenta diferenco inter ext kaj btrfs estas ke btrfs estas “BOVINO” Aŭ “Kopii sur Skribi” Filesystem. Tio ĉi signifas ke datumo estas neniam efektive intence anstataŭigita de la filesystem’s internals. Se vi skribas ŝanĝon al dosiero, btrfs will write your changes to a new location on physical media and will update the internal pointers to refer to the new location. Btrfs iras paŝon cetere en kiu tiuj internaj sugestoj (Plu-gvidita al kiel metadata) Estas Ankaŭ BOVINO. Pli malnovaj versioj de ext havus simple anstataŭigitan la datumo. Ext4 uzus Revuon certigi tiun korupton gajnis’t okazas devus la AC ŝtopas esti elretirita ĉe la plej inopportune momento. La revuaj rezultoj en simila nombro de paŝoj postulita ĝisdatigi datumon. With an SSD, the underlying hardware operates a similar CoW process no matter what filesystem you’re using. Tio ĉi estas ĉar SSDaj stiradoj povas ne efektive anstataŭigi datumon – Ili devi kopii la datumon (with your changes) to a new location and then erase the old block entirely. An optimisation in this area is that an SSD might not even erase the old block but rather simply make a note to erase the block at a later time when things aren’t so busy. The end result is that SSD drives fit very well with a CoW filesystem and don’t perform as well with non-CoW filesystems.

Fari aferojn interesanta, BOVINO en la filesystem facile iras manon mane kun ĉefaĵo vokis deduplication. Tio ĉi permesas du (Aŭ pli) Identaj blokoj de datumo esti entenita uzanta nur ununuran kopion, Savanta spacon. Kun BOVINO, Se deduplicated dosiero estas modifita, La aparta ĝemelo gajnis’t esti influita kiel la modifita dosieron’s datumoj estos estinta skribita al malsama fizika bloko.

BOVINO en ĝiradaj faroj Snapshotting Relative facile efektivigi. Kiam momentfoto estas farita la sistemon simple registras la novan momentfoton kiel estanta duplikatado de ĉiuj datumoj kaj metadata ene de la volumo. Kun BOVINO, Kiam ŝanĝoj estas farita, La momentfoto’s datumoj restas sendifektan, Kaj konsekvenca vido de la filesystem’s statuso ĉe la tempo la momentfoto estis farita povas esti daŭrigita.

A new friend

Kun la supra en menso, Precipe kiel Ubuntu faris btrfs havebla kiel instali-tempa elekto, Mi kalkulis ĝin estus bona tempo plonĝi en btrfs kaj esplori malgrandan. 🙂

Part 2 coming soon

Interŝanĝado
Thursday, January 01st, 2009 | Author:

Apparently, what operating system you use can say a lot about you. If you’re using some form of *nix, which distro you’re using can say a lot as well. Redundancy aside, I believe that a Linux distribution depends absolutely on its package management and distribution system.

I liked apt-get (1, 2) but there was some technical problem at some point and it caused me to use aptitude instead. Using aptitude is slightly easierit has more features automated into single, logical, commands where apt-get requires separate commands. Aptitude also has a curses-based GUI. If you’re not using the GUI then, other than brevity in terms of number of commands to learn, there is apparently no technical reason to prefer one over the other. Aptitude and apt-get serve K/X/Ubuntu and Debian well. From this point, I use the names Kubuntu and Ubuntu in a loosely interchangeable fashion.

In my use of CentOS (based on Red Hat), I’ve found I like yum. It seems to work in much the same as aptitudeone command to rule them all. It has some rather annoying default behaviour I’m not going to get into here as its most likely because I’m just not used to it. At least from a technical perspective, it is very good. I believe that Fedora also makes use of yum though my experience with Fedora is very limited.

the theory

Fedora and Ubuntu are in a class of distributions that have a fairly rigorous release cycle. Ubuntu 8.10 (the version is named so for the year and month of its release) will not, except for major bugs and minor changes, have another major update until the next version, Jaunty Jackalope. Ubuntu users have the latest versions of most software on their desktops right now. In the months preceding the next release, however, they’re not going to be so lucky unless they like usingbetareleases. As I’m not very familiar with Fedora, I’m not going to bother going into its release cycle.

These 2 distributions are also within a class of distributions known asbinary” Aŭ “binary-baseddistributions. This means that when you download an update, the files that are downloaded are precompiled and should run on anysupportedhardware. This isn’t specifically optimised for your desktop’s hardware, for example, your processor. Perhaps you have an AMD processor which has extra instruction support which Intel CPUs do not have. The reverse could also be true. For this reason, a binary-release distribution cannot optimise for one particular brand of hardware. Regardless of thisnon-optimisation”, it should run at a decent pace.

the practice!

About 2 years ago I started using Kubuntu. After a few months of working with it, I started to learn more about its specifics. I’m not much of a fan of using GUI tools to update the system when, ultimately, its all happening on the command-line anyway. The GUI tools just hide the complexity I don’t mind seeing.

I ended up making a bash script, update, which would run all the steps required to get aptitude to just go ahead and upgrade already, kthx?©, perhaps stopping along the way to back up my configuration, remount the NFS network share where we keep an on-site repository, back up the local cache of aptitude’s installed packages, do some folder-link shuffling to use a local copy if the network share couldn’t remount, sync between the local copy and the network share if the previous update had a network share issue, and update lists of packages in the repository. In general, it wouldn’t go ahead if there were any errors though, as you can tell, this script became a messy beast that went above and beyond the original requirements. It worked well for me.

Until the day came to update between Kubuntu 6.10 to 7.04. I did this manually though, not with the script.

I ended up reinstalling from scratch as a result of the mess that ensued. At least, as a backup administrator should do well to demonstrate, it was easy to recover everything I really needed. 🙂

What else is out there?

Even before I had to reinstall Kubuntu, I was introduced to another distribution called Gentoo. There are 2 very distinct differences between Gentoo and Ubuntu’s update system. The first is that Gentoo is a source-based distribution. This means that when you update a package, the package manager downloads the source and compiles everything, hopefully optimising it for your system. This, I think, is very cool. The downside to this is that compiling everything takes a very long time.

Here are my (very unscientific) estimates for the length of time it takes to install a basic GUI OS to a desktop from installation media, excluding extraneous drivers (for example, the latest 3D graphics drivers):

OS: minmax (median)

Windows Vista: 15 – 30 (20) minutes

Ubuntu: 15 – 40 (20) minutes

Gentoo: 3 – 40 (6) hours

Gentoo also requires much tinkering with the config files in order to get things workingthis is another reason for the extremely long delay between inserting the CD and booting your awesome* new desktop. Popular applications have binary packages available for downloadthough this isn’t a default option.

They see me rollin

There is one more very important distinction Gentoo has from most other distributions. It is arolling-releasedistribution. This means that there isn’t any rigorous version orreleasethat the distribution adheres to. If you install Gentoo todayif you finish installing Gentoo today, you’re probably going to have the latest version of all the applications you installed. If some obscure application gets a major update tomorrow, within a few days, if you update your system, you’re going to have that latest version on your desktop.

The difference between this rolling release and theotherdistributions is rather staggering. For example: If KDE 4.2 were to be released tomorrow, you’d probably have to wait less than 2 weeks for it to be available on Gentoo. Ubuntu users might have to wait till 9.04 – that’s a 4-month wait.

Something more suitable?

Personally, I’m not willing to put in the 40 hours of effort to get my system working the way I want it to. My colleague had to reinstall recently for some obscure reason and it turns out he wasn’t willing to put in the 6 hours (he’s more experienced with Gentoo) of effort to get his system back to how it was running either. Instead, Arch Linux caught his eye. Arch Linux is a rolling-release (like Gentoo), binary-based (like Ubuntu) distribution. Its packages (well, the vast majority of them) don’t need much tinkering with their config files to get things working nicely either. Its the best of both worlds!

You still need to know what you’re doing* but if you’ve come to this juncture, it shouldn’t be such a giant leap of faith. Arch Linux’s package manager, called pacman, has built-in dependency and conflict handling. I use another package manager, yaourt (French for yoghurt), which has very quickly become popular with Arch users. Yaourt enhances the functionality of pacman by allowing you to download and install applications directly from the AUR, Aŭ Arch User Repository. This repository contains scripts that allow you to automatically download and install many applications that would otherwise be completely unsupported by Arch’s own core developers. It downloads and compiles the package into a chroot’d environment. It then packages the chroot’d environment into a pacman-compatible package tarball and uses pacman to deploy it into your system.

ankaŭ, the AUR supports a voting system whereby popular packages get placed into the more official [community] repository. Yaourt also supports an automated voting mechanism whereby, after installing a package via AUR, it asks if you want to vote for its inclusion in [community].

I estimate that the time taken for my Arch installation was about 90 minutes. I don’t recommend Archlinux for newbies though I do recommend it for any Linux user who’s gotten bored with other distrosand wants to get into the nitty gritty without having to install Linux From Scratch. Arch Linux has been getting pretty popular these days. Its currently at number 14 on Distrowatch.

* IF you know what you’re doing. AND YOU BETTER BLOODY KNOW WHAT YOU’RE DOING!
Interŝanĝado