Page 2 of 4 FirstFirst 1234 LastLast
Results 11 to 20 of 34

Thread: partition/volume

  1. #11

    Default Re: partition/volume

    Any comments on dup + btrfs = bit repair on a single drive (?)

  2. #12

    Default Re: partition/volume

    OK... Here goes nothin' ...

    Code:
    ~> sudo mkfs.btrfs -f --data dup --metadata dup -L Ext-BtrFS_00 /dev/sdd
    btrfs-progs v4.19.1 
    See http://btrfs.wiki.kernel.org for more information.
    
    Label:              Ext-BtrFS_00
    UUID:               0fadb03e-ce95-486f-97fd-a04603553126
    Node size:          16384
    Sector size:        4096
    Filesystem size:    4.55TiB
    Block group profiles:
      Data:             DUP               1.00GiB
      Metadata:         DUP               1.00GiB
      System:           DUP               8.00MiB
    SSD detected:       no
    Incompat features:  extref, skinny-metadata
    Number of devices:  1
    Devices:
       ID        SIZE  PATH
        1     4.55TiB  /dev/sdd
    ~>
    references
    https://zoomadmin.com/HowToLinux/Lin...and/mkfs.btrfs
    https://zejn.net/b/2017/04/30/single...cy-with-btrfs/

  3. #13
    Join Date
    Jun 2011
    Location
    Germany
    Posts
    290

    Default Re: partition/volume

    Hi pattyM,

    Sorry, I don't have enough knowledge to comment on your question about dup + Btrfs. However, to most issues I prefer a pragmatic approach. Therefore I usually (try to) ask myself, "Is it worth the bother?". If it comes to backup the question is, what do you want to achieve? I am concerned about bit rot, too. That mostly considers my digital "valuables", memories etc. But a large part of the snapshots taken by Btrfs is just the operating system. The snapshots are supposed to make it easier to recover. So, does it make sense to make too big a fuss of conserving my OS 100%? It might be easier to backup the relevant settings. If the "normal" rollback doesn't help anymore, just go for the fresh install and restore your settings. Most should be in /etc/ aside from /home/user. There may be more in /usr/... . For a lot of things, just taking notes of your setup may yet be easier than trying to restore it from backup. IMHO, everybody needs to define his / her "breakeven point" of backup efforts vs. backup benefits.
    As for your question: In order to use dd you have to unmount the drive in question (AFAIK). For regular backups I think it's not very handy. It won't bother about snapshots, filesystem or anything but just clone everything. So it's a very thorough way if not some kind of overkill.
    I think you use rsync because it will do incremental backups?
    I do like the incremental backup but I revert to unison rather than rsync - being pragmatic. It has a GUI which - if needed - helps you getting started with huge backups (or rather syncs). You can easily check what will be changed before hitting "go". But once your backup / sync roots are established, you can let it run in the background, text mode, batch mode which is very fast - similar to rsync. It can use rsync mode as well, BTW. You can put it in a wrapper script and read out the return value if sync was ok. If not, the log files is very detailed.
    And the documentation is quite good once you found it in /usr/share/doc/packages/unison/unison-manual.html after installing.

  4. #14
    Join Date
    Jun 2011
    Location
    Germany
    Posts
    290

    Default Re: partition/volume

    ...a large part of the snapshots taken by Btrfs is just the operating system.
    Sorry, forgot to add: That's assuming your /home is a logical volume of Btrfs. If it is a separate partition it will have it's own file system and the snapshots will be 100% operating system.

  5. #15

    Default Re: partition/volume

    Yes, --data dup --metadata dup cut the size of the drive in half, as you would expect.

  6. #16

    Default Re: partition/volume

    Quote Originally Posted by kasi042 View Post
    Sorry, forgot to add: That's assuming your /home is a logical volume of Btrfs. If it is a separate partition it will have it's own file system and the snapshots will be 100% operating system.
    I would agree that backing up the OS is not usually necessary - but backing up the /home/user directory can be really important. I think I had some fairly serious bitrot on my system, or something that has a similar effect.. I had upgraded from 42.1, stepwise, but when the time came for the 15.1 -> 15.2 upgrade, there were some issues, and my /home partition had been around a LONG time. A big one seemed to be associated with Firefox. I was forced to go back to backup to get ff going again. But there were issues with that, too.

    I do tend to keep things around as long as possible, so I do care a lot about phenomena such as bitrot - I don't know of any others specifically - but hd crashes and software crashes, OS hangs, etc. tend to pile up in their effects on data and apps, especially big, complex ones like KDE and ff.

    So BtrFS can be set up to "dup" your data, and make it more or less immune to bitrot - but it cuts your drive size in half - BUT there is also lzo/zlib compression, so that may partially compensate. Also there are snapshots - I am not sure how these really work yet - I think they also consume drive space, eventually, significant drive space. So BtrFS still has a way to go.

  7. #17
    Join Date
    Jun 2011
    Location
    Germany
    Posts
    290

    Default Re: partition/volume

    Yeah, I remember you Firefox problem. I have just posted some update in that thread.

    I will now check your link about Btrfs and DUP. I am going to replace both HDD in the raid on my homeserver and now I'm curious. I have never considered using Btrfs for pure data drives without OS. Would anybody recommend that?

  8. #18

    Default Re: partition/volume

    Quote Originally Posted by pattiM View Post
    Yes, --data dup --metadata dup cut the size of the drive in half, as you would expect.
    Except, apparently, for SSD's. This apparently doesn't work with SSD's because they deduplicate files/metadata to save storage space? So my laptop has room for two hard drives - maybe I could use one SSD as the BtrFS backup for the other? I think this wouldn't work (but I don't know) because BtrFS needs a defined RAID to do backup - and dual-HD laptops don't usually have RAID capability.

  9. #19

    Default Re: partition/volume

    Quote Originally Posted by kasi042 View Post
    Yeah, I remember you Firefox problem. I have just posted some update in that thread.

    I will now check your link about Btrfs and DUP. I am going to replace both HDD in the raid on my homeserver and now I'm curious. I have never considered using Btrfs for pure data drives without OS. Would anybody recommend that?
    Well, BtrFS is a default FS in many big Linux distros now. Since it can auto-repair (and compress, etc.) bit errors, I would go for it. But I only use a laptop for my main computer, so I don't know if I can do this.

    Thanks for the ff update. I just gave up. I should maybe move to some less trouble-prone browser. I think my problem(s) with ff may have related to undetected bit-rot or just accumulations of bit-write-errors. My /home directory has been literally the same partition since 42.1 or thereabouts. That's a long time. So that's a strong argument for BtrFS for folks like me.

  10. #20

    Default Re: partition/volume BtrFS - DUAL DRIVES?

    Does anyone know enough about BtrFS to know if it can be used with dual hard drives (SSD's) to get auto bit-error-correction? Do you just tell BtrFS that both drives are part of the same FS, but tell BtrFS that one drive is the backup data/metadata for the other?

    (this sounds complex and I don't know if it would work)

Page 2 of 4 FirstFirst 1234 LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •