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Path `/boot/grub' is not readable by GRUB on boot. Installation is impossible. Aborting

Whenever I try updating grub, I get this error: # grub-install /dev/sda Path `/boot/grub' is not readable by GRUB on boot. Installation is impossible. Aborting. and # grub-mkconfig -o ...
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22 views

What is Btrfs's disk space caching?

I noticed in my syslog that BTRFS reports enabling "disk space caching". What is Btrfs's "disk space caching"?
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BTRFS & F2FS userspace utilites cross compilation

Is there any weblink/document which describes the steps to cross-compile btrfs & F2fs user space utilities ? Any steps ? special tuning suggestion for arm based board.(AM335x) ?
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What are btrfs snapshot and subvolume restrictions speaking in terms of read/write access instead of access and data sharing?

The btrfs subvolume manpage tries to explain which type of access is granted to btrfs subvolumes and snapshots. Unfortunately it exclusively uses terms like "access", "use just like a directory" and ...
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1answer
30 views

Mirror / backup laptop btrfs drive to sometimes connected external USB disk

I have a laptop with an internal drive using btrfs. There are several subvolumes and snapshots on here. I want a copy of this drive to be made periodically to an external USB disk of approximately the ...
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17 views

how to delete btrfs snapshot?

sudo btrfs subvolume show / outputs / Name: @ uuid: 1f0da442-cdf3-144c-a4ce-f6c06248cfde Parent uuid: - Creation time: 2014-08-16 19:06:51 Object ...
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41 views

Online Drive Replacement: BTRFS with RAID 6

on a testing machine I installed four HDDs and they are configured as RAID6. For a test I removed one of the drives (/dev/sdk) while the volume was mounted and data was written to it. This worked ...
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9 views

btrfs device total usage differs from the sum of each usage

My system lays on a btrfs with 3 disks. btrfs fi show outputs: Label: none uuid: 75a8f1e7-7d79-4a05-8f88-fe02d119bf9f Total devices 3 FS bytes used 14.84GiB devid 1 size 7.74GiB used ...
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31 views

How come system snapshots are so small in size?

So let’s say a have a file called bob with the size of 10GB in /home. I make a snapshot of /home and delete the original bob file. However I can still access the bob file because I have a snapshot it. ...
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76 views

Mirror / backup laptop btrfs drive to sometimes connected external USB disk

I have a laptop with an internal drive using btrfs. There are several subvolumes and snapshots on here. I want a copy of this drive to be made periodically to an external USB disk of approximately the ...
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63 views

BTRFS or LVM heterogeneous RAID

I'm entertaining creating a largish (3.5TB+) backup server for my family. I already own enough hardware, and I don't want to buy any more right now. The config I envision look like this: Two 1TB ...
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18 views

How to figure out which partition number an entry in the list has in the Fedora 20 installation routine?

I started the Fedora 20 installation image which I dded onto an USB stick. During the installation I started wondering whether it really is impossible to determine the parition number or UUID of ...
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34 views

It is possible to minimize size of a btrfs sparse file with btrfs filesystem resize and truncate?

Motivation: Assume I have created an oversize sparse file with truncate -s 4T test.img, mounted it over a loop device and put inside 1M files with 100 GB size together. One can assume that btrfs put ...
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1answer
207 views

Btrfs raid level for large NAS (8+ 5tb disks)

I'm planning to build a new NAS to store a large amount of media (20tb+). I would like to use btrfs for both the NAS and the backup (might be a separate system, not sure yet) I want to use raid1 or ...
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42 views

BTRFS multiple devices mix raid1 and raid0

Hi Consider the following use case: I have two disks same size (let's say 3TB each). Then create a btrfs filesystem using both devices. Now I want to have two subvolumes "idata" and "ndata". Where ...
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2k views

ext4 vs btrfs performance on SSD array

I am observing something that I cannot explain. I am trying to come up with a good filesystem configuration using HP P420i controller and SSDs. Out of curiosity I have tried BTRFS (still unstable so I ...
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53 views

Is there something analogue to LVM logical volumes in BTRFS?

I like the way BTRFS does snapshots and subvolumes but it does not feel right to use LVM just because I want my logical volume to be of certain size. Is there something analogue to LVM logical ...
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59 views

How do I deal with BTRFS raid1 when usb disk device mappings changes?

I created a btrfs raid1 one by using "mkfs.btrfs /dev/sdc1 /dev/sdg1". It worked fine but next time I restarted my pc it seemed like the sdg device became sdf therefor btrfs refused to mount this ...
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26 views

btrfs won't run from cron

I'm trying to set up a cron job to create a btrfs subvolume snapshot of my root partition. The command works perfectly if I run it from the command line, but nothing happens at the scheduled cron ...
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180 views

How to snapshot a btrfs root file system (snapshot of /)?

I have Fedora 20 and when I installed it I choose to go with btrfs as file system, by many reasons but mainly to have snapshots available. But I can't seem to create a snapshot of /. I can snapshot ...
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241 views

How to monitor BTRFS filesystem raid for errors?

I saw some documentation on a daemon that can execute a program/script for various BTRFS events, but I cannot find it anymore. How can I have a script/program be executed on a drive failure for a ...
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1answer
197 views

partitioning and subvol strategy with btrfs

I'm new to btrfs and I'd like some advice on partitioning and subvolume strategy. The system is a light-duty web server, and assume it only has a single disk. With ext filesystems, I've always ...
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21 views

Are re-combined BTRFS incrementals identical to the original?

I have several systems running btrfs, and I'd like to use the btrfs subvolume send/receive features as a backup solution. I want to send daily incrementals to remote as efficiently as possible. That ...
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105 views

Is it possible to convert a btrfs RAID5 to a RAID6 with the same disks without losing data?

How would I convert an existing RAID5 (single parity) btrfs setup to a dual parity RAID6 configuration given enough free available disk space, using the same disks, without swapping out data ? ...
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90 views

RAID 0 or btrfs on two SSDs?

I have two 500 GB SSD's, and I would like to combine the two in some way to have 1 250 GB NTFS partition, and 1 750 GB btrfs or ext4 partition. As far as I see, I have two options: the Intel Rapid ...
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222 views

Is RAID1 or similar needed for btrfs/ZFS to protect against bit rot?

I'm running a file server using Linux software raid, set up as raid6. As filesystem I've chosen btrfs. However, I'm not using btrfs own raid6 implementation as it's not very stable yet. So basically, ...
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1answer
741 views

How to recover this btrfs error?

I have a btrfs file system that cannot be mounted anymore. I resetted the computer and after boot a Java process crashed, showing a core dump with much btrfs stuff on the stack. After that happened, ...
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41 views

Is there a way to show RAID details in a similar way to MDADM?

I find mdadm --detail <device> very useful when I need to know what is going on with the device (/proc/mdadm too). Example: /dev/md0: Version : 1.2 Creation Time : Mon Mar 4 ...
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98 views

btrfs does not show drive as missing

I am trying out btrfs and I noticed some funny behaviour: I have two drives in a raid 1 configuration. sudo btrfs fi show Label: none uuid: 52b9c6f6-ce5c-4727-861e-e2fd012e475f Total devices 2 ...
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1answer
733 views

Reasoning behind hosting virtual disk images on BTRFS Filesystem

I have been reading about BTRFS and ZFS for a while and while I do appreciate the benefits of CoW when hosting important files I am currently puzzled by the following dilemma: Given that both ZFS and ...
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1answer
650 views

Full BTRFS partition unusable

I have an extremely critical set of circumstances. I installed snapper on my Fedora 20 box. It created around 20 snapshots. My btrfs partition is now full of snapper subvolumes. My partition became ...
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217 views

Is Btrfs vulnerable to RAID write hole effect?

If not, does it mean that Btrfs in RAID mode is fully resistant to power failure?
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1k views

Can a failed Btrfs drive in RAID-1 be replaced live?

I am trying to decide on a filesystem and would like to know if it is possible to replace a failed drive in btrfs RAID without downtime. Suppose I create a new btrfs filesystem using the command ...
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1answer
38 views

Hierarchical snapshots strange behaviour

I have divided my drive into two btrfs paritions: one is mounted as / (dev/sda1), second one as /home (/dev/sda2). I made my initial snapshot of /home: mkdir -p /home/snapshots/mnt mount -o ...
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1answer
507 views

How do I find out the compressed / uncompressed file sizes on btrfs?

I am using btrfs on one of my hard drives. I would like to know the actual file size and the compressed file size on btrfs. I am interested in seeing the compression ratios per file . For example ntfs ...
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76 views

Btrfs snapshot space and time overhead

Using btrfs-snapshot-rotation, I've setup a system to rotate snapshots so that it always has snapshots of: Each of the the last 24 hours Each of the last 30 days Each of the last 12 months. This ...
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70 views

For raid1, does btrfs check which partitions are on the same device?

I have btrfs on two partitions using btrfs's raid1 mode: /dev/sda3 /dev/sdb3 Now I plan to run btrfs device add /dev/sda2 /dev/sdb2, so I'll have four partitions: /dev/sda2 /dev/sda3 /dev/sdb2 ...
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1k views

btrfs: HUGE metadata allocated

I have a 256GB SSD disk on which I converted my ext4 root FS to btrfs. I erased the ext4 backup subvolume, enabled compression and defragmented recursively to enable it on all files. btrfs fi df / ...
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214 views

Does mounting a btrfs subvolume work recursively?

With the following subvolumes on a btrfs filesystem on /dev/sda3: root root/home and the following mount: /dev/sda3 on / Is the /home folder on the root subvolume, or on the root/home subvolume? ...
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272 views

Is it currently stable to use, and boot to, a btrfs RAID 0 on SSDs?

As of the current (3.10+) Linux kernels, is it supported to make a btrfs RAID 0 out of SSDs the root mount and boot to it? This comprises several issues: Does the RAID 0 with SSDs support ...
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1answer
340 views

Can I merge two btrfs without data loss

I have a btrfs device mounted, it is composed of 2 partitions and it is in single mode (the partitions does not have the same size so I can't use raid 0 ). I have another disk formatted in ext4, I ...
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1answer
495 views

How can I delete a apt-btrfs-snapshot when the error is “Directory not empty?”

There is one snapshot created by apt-btrfs-snapshot that won't delete Delete subvolume '/tmp/foo/@apt-snapshot-2013-04-XX_1X:3X:XX' ERROR: cannot delete ...
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1answer
153 views

btrfs: one whole device + one partition on another device (no data-mirroring), viable?

Currently, /home claims 880G of a 1TB drive. Photos are eating this up quickly, so I want to add a 1TB drive I have lying around to the computer to expand /home. I figured I could use btrfs (I don't ...
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How to copy a btrfs filesystem

How can make a full copy of the contents of a btrfs filesystem? By full copy I mean not only the current data, but also different subvolumes with their snapshots, ideally preserving their CoW ...
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2k views

Btrfs Undelete File

I would like to undelete a large file I deleted using the rm -r command on the directory it was located in. The file was on a 1TB usb external harddisk. Nothing was written to the disk after the file ...
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134 views

Linux kernel 3.9 new storage features howto?

Linux kernel 3.9 has been released, which brings new features for storage cache devices (dm-cache), as well as BTRFS RAID 5/6. These features are undoubtedly sexy, but are all but completely ...
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470 views

How do I reinstall/enable snapper?

I had errors in my root filesystem (btrfs) so I recreated it from a backup but now, snapper doesn't work anymore: # /usr/bin/snapper -v -v -v -v create --description test IO Error. # snapper -v ...
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6k views

Does rsync --inplace write to the entire file, or just to the parts that need to be updated? (for btrfs+rsync backups)

I was reading several guides how combine btrfs snapshots with rsync to make an efficient backup solution with history. However it all depends on if rsync --inplace modifies only those portions of ...
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415 views

Is it safe to resize a BTRFS partition that is part of a multi-device volume?

I have a multi-device BTRFS volume and I would like to re-size one of the partitions. To be more precise: My /home is spread across two separate BTRFS partitions. I shrunk down another partition to ...
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304 views

Is it possible to have subvolumes with different replication modes in btrfs?

I am setting up a system with two 3TB hard drives as storage backing. As it's a desktop station, I thougth about the following disk setup: sda + /boot with 500MB + btrfs for the remaining GBytes sdb ...