[gentoo-user] Re: planned btrfs conversion: questions
-BEGIN PGP SIGNED MESSAGE- Hash: SHA512 On 05/06/2014 06:18 AM, Marc Joliet wrote: > Hi all, > > I've become increasingly motivated to convert to btrfs. From what I've seen, > it has become > increasingly stable; enough so that it is apparently supposed to become the > default FS on > OpenSuse in 13.2. > > I am motivated by various reasons: > > - The experience of insignificant data loss after a reboot after no (visible) > problems during > normal operations (no similar occurrence since). I suspect this would have > been discovered > sooner by btrfs' data checksumming. > > While the data lost was of a small amount, not to mention insignificant > (internet pictures) and > could be retrieved again easily, I worry that this sort of silent corruption > might happen to > data that I *do* care about. My backups would become less than useless if I > were to discover > such corruption too late. > > - The outright sexy multiple device support :) . > > This migration will occur in conjunction with a migration of / + /usr to a > cheap SSD that I > just bought (Crucial M500 120 GB). The overall plan is thus as follows: > > Replace > > /boot on /dev/md1 (EXT3, RAID 1) / (with assorted sub-directories, sans /usr) > on /dev/md2 > (EXT4, RAID 10) the rest on LVM on /dev/md3 (all LVs EXT4, RAID 10) > > with > > / + /boot + /usr + swapfile on the SSD (EXT4) the rest (/home, my media > partitions) on a btrfs > RAID 10 > > (which replaces an older plan to recreate the RAID 10 + LVM to use the whole > disks with the > current 1.2 metadata format) > > The goals are, in addition to alleviating my data safety concerns above, to > guarantee that I > don't need an initramfs at boot (hence the SSD), and to greatly simplify my > partitioning scheme > (I just have too many separate logical volumes ;-) ). Any added performance > is "just" a nice > bonus. > > The reason why I would choose EXT4 for the SSD is that btrfs still lacks > support for swap files > and I worry about creating a swap partition on the SSD. Is that warranted, or > will the > wear-levelling of the SSD handle that just fine? Do swap partitions support > SSDs specially? > Also, does anyone know whether EXT4 goes beyond "merely" supporting TRIM? > That is, the btrfs > wiki advertises the following: > > "SSD (Flash storage) awareness (TRIM/Discard for reporting free blocks for > reuse) and > optimizations (e.g. avoiding unnecessary seek optimizations, sending writes > in clusters, even > if they are from unrelated files. This results in larger write operations and > faster write > throughput)" > > Does EXT4 also implement such optimisations for SSDs? > > So I guess I want to know: does anybody have any further suggestions to make? > Is btrfs a good > choice for / after all? And should I be using the most recent kernel > versions? (I would go with > no, despite the advice from upstream, because the changes in the last two > versions don't seem > to be particularly user visible, at least to me, from reading > kernelnewbies.org.) > > I also have a more specific question regarding RAID 10: the btrfs wiki says > that you can add > devices with different sizes to a multiple device setup, but I don't think it > says to which > RAID levels this applies and how. From [0] I would say it works with RAID 10 > (since that's what > the example uses), but thought maybe somebody here knows more details and/or > gotchas. From my > understanding, this means that I can iteratively upgrade my RAID 10 to larger > drives and have > btrfs use all of the available space (or at least as much as is possible). > This is important to > me because I currently have 4 320 GB HDDs + 1 (possibly broken, must check) > spare and wish to > be able to upgrade without having to buy four HDDs at once. > > Now to the migration plan: first, partition the SSD and copy all relevant > file systems to it; > this will be done from a Live-CD (SystemRescueCD). After I have configured > the mount options > appropriately and can boot from that, I should be able to mount the other > file systems (/home > and my media partitions) read-only from the actual system and do the RAID + > LVM -> btrfs > migration from there. > > Note that I will in general follow the advice from [1-3], and if people > recommend btrfs on /, > then I will also try to get relevant information from [4]. > > [0] > https://btrfs.wiki.kernel.org/index.php/SysadminGuide#RAID_and_data_replication > [1] > https://wiki.archlinux.org/index.php/Solid_State_Drives [2] > https://wiki.archlinux.org/index.php/Btrfs [3] > http://wiki.gentoo.org/wiki/Btrfs [4] > http://wiki.gentoo.org/wiki/Btrfs_system_root > > Greetings and thanks in advance for any help given > As I understand it, when you use BTRFS's internal "RAID1" implementation, the filesystem ensures that all the data is on at least two different drives, but otherwise doesn't require that the drives are the same size, etc. The am
Re: [gentoo-user] Re: planned btrfs conversion: questions
(FYI: your off-list forward of this email arrived at about the same time as this one (at about 22:20 CET), strangely enough.) Am Tue, 6 May 2014 18:13:07 + (UTC) schrieb James : > Marc Joliet gmx.de> writes: > > > > I've become increasingly motivated to convert to btrfs. From what > > I've seen, it has become increasingly stable; enough so that it is > > apparently supposed to > become the default FS on OpenSuse in 13.2. > > > I am motivated. > > Greetings and thanks in advance for any help given > > > Good news Marc, > > Last December I was on the BTRFS train. The docs team was totally > in agreement with my (your ?) enthusiasmn for all things BTRFS; including > but not limited to the development of documentation of how to install, from > scratch, a complete Gentoo system, centric around BTRFS. The goal was for a > group to develop documentation on the the gentoo wiki for this adventure. That would be neat :) . I found it really annoying having to piece lots of the details together myself. I'm kind of in the middle of a Masters thesis here... Although I admit this sort of activity satisfies my inner Linux geek ;-) (there's a reason I like Gentoo, after all). And it will hopefully be satiated for a while now after setting up automated backups, migrating / to an SSD along with switching to grub2 (which I already use on my borrowed work/uni laptop) in the process, *and* migrating an mdraid + LVM setup to btrfs -- all within about one week :) . > Unfortunately, as a single parent, entrepreneur, and handyman living in a > fixer_upper, my free time is rather scant these months of 2014. > After some seriously needed projects are closed out, I'll have much > more time; hopefully in some weeks rather than months. My goals was to > clearly delineate possible explicit installation syntax for the smoother > integration (mastery?) of grub2, (u)EFI and BTRFS into a new gentoo > installation. > > > So if you don't mind, I'd like to parse out good ideas (from your efforts) > and start this doc on the Gentoo wiki, based in part on your conversion > adventures. I would not even be upset, if some other, younger, > sharper mind wanted to develop a gentoo-wiki doc, based on your adventures. > Also, I'm hoping others are keenly inspired to contribute to your efforts > and some experimental installation docs on the gentoo wiki. This is the > gentoo community's chance to influence future gentoo installation docs, in > a non threatening manor. ^ This one looks pretty non-threatening to me ;-) : https://4.bp.blogspot.com/-9usBSoPnUWo/TaMmrclJngI/AD4/8Xqx67g6U34/s1600/DSC06646.JPG > BTRFS is on the fast track in many linux distros, > as well as cloud/super computers architecture and embedded 64bit arches > as the main file system of choice. That sounds perfectly fine to me (the parsing out good ideas from this thread, I mean, but btrfs being on the fast track is also good :) ). > I've been espousing (as have many others) for a long time on the > convergences of embedded linux and full_bloat linix for some time. Here is > one gentoo_distro where the author experiments with many of the issues > related to convergence. There is even some suggestions on using BTRFS on > gentoo found here. [1] [...] > [1] https://wiki.gentoo.org/wiki/Project:Hardened_uClibc/Lilblue That looks interesting, albeit outside my (current) realm of interest. I can imagine playing with that sort of thing in the future (1+ years), though. Greetings, -- Marc Joliet -- "People who think they know everything really annoy those of us who know we don't" - Bjarne Stroustrup signature.asc Description: PGP signature
[gentoo-user] Re: planned btrfs conversion: questions
Marc Joliet gmx.de> writes: > I've become increasingly motivated to convert to btrfs. From what > I've seen, it has become increasingly stable; enough so that it is > apparently supposed to > become the default FS on OpenSuse in 13.2. > I am motivated. > Greetings and thanks in advance for any help given Good news Marc, Last December I was on the BTRFS train. The docs team was totally in agreement with my (your ?) enthusiasmn for all things BTRFS; including but not limited to the development of documentation of how to install, from scratch, a complete Gentoo system, centric around BTRFS. The goal was for a group to develop documentation on the the gentoo wiki for this adventure. Unfortunately, as a single parent, entrepreneur, and handyman living in a fixer_upper, my free time is rather scant these months of 2014. After some seriously needed projects are closed out, I'll have much more time; hopefully in some weeks rather than months. My goals was to clearly delineate possible explicit installation syntax for the smoother integration (mastery?) of grub2, (u)EFI and BTRFS into a new gentoo installation. So if you don't mind, I'd like to parse out good ideas (from your efforts) and start this doc on the Gentoo wiki, based in part on your conversion adventures. I would not even be upset, if some other, younger, sharper mind wanted to develop a gentoo-wiki doc, based on your adventures. Also, I'm hoping others are keenly inspired to contribute to your efforts and some experimental installation docs on the gentoo wiki. This is the gentoo community's chance to influence future gentoo installation docs, in a non threatening manor. BTRFS is on the fast track in many linux distros, as well as cloud/super computers architecture and embedded 64bit arches as the main file system of choice. I've been espousing (as have many others) for a long time on the convergences of embedded linux and full_bloat linix for some time. Here is one gentoo_distro where the author experiments with many of the issues related to convergence. There is even some suggestions on using BTRFS on gentoo found here. [1] sincerely, James [1] https://wiki.gentoo.org/wiki/Project:Hardened_uClibc/Lilblue
