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Questions tagged [zfsonlinux]

zfsonlinux provides a native Linux kernel port of the ZFS filesystem so that ZFS may run natively on Linux. It is very different from ZFS-fuse which provides ZFS on top of a userspace-filesystem layer. The ZFS On Linux project is hosted on zfsonlinux.org.

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ZFS ARC ghost memory usage

Are arcstats:mru_ghost_evictable_metadata and arcstats:mfu_ghost_evictable_metadata the number of bytes stored in RAM by the arc ghost list? If so, is this memory usage also accounted for in the ...
m7913d's user avatar
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127 views

zfs pool online but can't be imported "one or more devices is currently unavailable"

I recently moved my zfs pool from a 5 bay drive to a 10 bay drive and it can not be imported any more. The pool (nextcloud) appears to be online but when I tried to import it, it throws "one or ...
Oliver Hu's user avatar
3 votes
2 answers
631 views

ZFS: Handling massive no. of concurrent RW operations and failover

I have a single ZFS/Linux instance with a file that can grow to those crazy sizes supported by ZFS. A large number of concurrent users need to read/write from/to this file over the public inter net. ...
Harry's user avatar
  • 463
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0 answers
49 views

Access to ZFS pool when one drive has failed is incredibly slow

I have a ZFS box that I inherited that is having a lot of issues. Checking the status I see there are a few drives with issues: ganymede $ zpool status -x pool: dpool state: DEGRADED status: One or ...
Bob Odenkirk's user avatar
0 votes
2 answers
82 views

Why is /etc/mtab a relative symlink

I've just spent a few hours trying to figure out why NFS exports were not working on a Proxmox (based on Debian) server. "Not working" in this case means that the mount command times out on ...
Philipp Burch's user avatar
4 votes
2 answers
3k views

ZFS on Linux disk replacement best practices

I have an 8-bay NAS running Fedora 29 (kernel version 4.20.8) and zfs version 0.7.12. All of the drive bays are used for a zfs pool named “tank.” Here is the zpool layout: tank mirror-0 sda ...
user489879's user avatar
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/dev/zvol/pool/group/srv points to partition zd0p16 not volume zd0 - bug or feature?

I am only starting to get familiar with openzfs 2.2.0 on Linux (Ubuntu kernel 6.5) and immediately ran into something strange. A symlink I was expecting to point to a zvol block device.. was pointing ...
anx's user avatar
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5 votes
2 answers
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Can ZFS send/receive help me recover from partial pool loss after upgrade to Ubuntu 22?

I have a long-running ZFS pool under Ubuntu, which has been through many upgrades. After upgrade from Ubuntu 20 to 22, the encrypted filesystems refuse to mount, though the rest seem OK. zpool ...
rptb1's user avatar
  • 161
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1 answer
39 views

zfs force import multiple VMS (IDs) and now can't find VM but it's not missing according to zfs?

I'm completely new to ZFS. Today, I did something stupid and caused a problem where I need to recover my entire OS. On a live OS I'm using to recover my machine, I need to mount my ZFS volumes for ...
Jim's user avatar
  • 355
3 votes
1 answer
841 views

What ZFS pool, vdev and dataset properties should most people use?

ZFS has many different configurable properties for pools, for vdevs and for datasets. Many of those can be changed at any point, but some can only be set at creation time (or only affect data written ...
Joachim Sauer's user avatar
3 votes
1 answer
878 views

Why doesn't ZFS vdev removal work when any raidz devices are in the pool?

First: I'm perfectly okay with accepting that this is the case for now and am not looking for an immediate solution, rather I'm trying to understand the technical limitation for this constraint. I'm ...
Joachim Sauer's user avatar
0 votes
1 answer
98 views

Can I mirror a 2-disk striped zpool to a single large drive?

Currently I have a 4TB pool with two striped drives: # zpool status pool: lxd state: ONLINE status: Some supported features are not enabled on the pool. The pool can still be used, but some ...
Arni J's user avatar
  • 75
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1 answer
340 views

ZFS I/O Error, Kernel Panic during import

I'm running a raidz1-0 (RAID5) setup with 4 data 2TB SSDs. During midnight, somehow 2 of my data disks experience some I/O error (from /var/log/messages). When I investigated in the morning, the zpool ...
Jealous_Donut_7128's user avatar
0 votes
2 answers
136 views

How does zfs know which snapshots to send with the `-I` flag?

From the manual: A group of incremental snapshots can be combined into one snapshot by using the zfs send -I option. For example: # zfs send -I pool/fs@snapA pool/fs@snapD > /snaps/fs@all-I How ...
Manuel Schmidt's user avatar
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0 answers
111 views

Persistent ZFS pool errors on Ubuntu, even after repeated scrubs

My 3-disk ZFS pool has been scrubbed several times after replacing failing disks. "zpool status -v" provided a list of files which were deleted and removed a good number of errors. Despite ...
Paul Leyland's user avatar
0 votes
1 answer
127 views

Samba and ZFS resulting in NT_STATUS_BAD_NETWORK_NAME

I am currently trying to share my ZFS dataset using SMB. Unfortunately I receive the error NT_STATUS_BAD_NETWORK_NAME every time I try to connect to the share. The error does not make much sense to me ...
mchp's user avatar
  • 41
1 vote
1 answer
666 views

ZFS on Hetzner Rescue fails with `checking whether inode_owner_or_capable() takes user_ns... configure: error:`

Normally, when booting into the Hetzner rescue system, using the 'zfs' command will automatically install zfs tooling inside the rescue system. This is currently not working; checking whether ...
TinkerTank's user avatar
3 votes
0 answers
416 views

zfs pool with slow speed on SAS drive with high latency

We have 3 servers in a gluster pool. Each computer's spec is (Advance STOR-2 Gen 2 at OVH): AMD Ryzen 7 Pro 3700 - 8c/16t - 3.6 GHz/4.4 GHz 6 x 14 TB disk (WD DC HC 530, using CMR technologies) ...
Dboy's user avatar
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2 votes
1 answer
157 views

How to explain that ZFS' snapshot reports 'WRITTEN' as 4.26GB, but the transfer size is actually 31.4GB?

When I run this query on a dataset zfs list -d 1 -t all -o name,used,refer,written,compressratio sfg-backup/mx I see the following stats: zfs list -d 1 -t all -o name,used,refer,written,compressratio ...
dimus's user avatar
  • 337
3 votes
1 answer
817 views

Forcefully forget / unmount ZFS pool after drives disconnected

First off, I made a mistake & I acknowledge that, but now I'm stuck with a "broken" ZFS driver and want to restore it without rebooting my machine. How I can say ZFS on Linux to just ...
Felix Stupp's user avatar
0 votes
0 answers
145 views

Unexpected ZFS async write performance at different queue depths

For some reason, QD2 seems to be the best in terms of raw IOPS... After seeing an interesting article comparing a couple different drives for SLOG usage, I got curious about the performance of my own ...
Sam's user avatar
  • 109
0 votes
1 answer
836 views

ZFS pool disappears and says "I/O error" because of one missing device

I had a ZFS pool named data with 3 disks. Two disks were attached to the raidz by ID, but the third one was attached by volume (sda). I physically removed the sda device because I wanted to attach it ...
Alex Shaw's user avatar
  • 539
0 votes
1 answer
1k views

ZFS send/receive fails, target has been modified, because of a zfs userspace query?

I use zfs send/receive to replicate a zfs file system to another server every day. The workflow is the standard send receive: # 1. create snapshot on source zfs snapshot ${source_fs}@${today} # 2. ...
Sethos II's user avatar
  • 527
2 votes
3 answers
1k views

How to nest & share multiple ZFS pools over Samba to multiple users

I have the following ZFS structure: % sudo zfs list 16:03:46 NAME USED AVAIL REFER MOUNTPOINT zpool1 ...
ifiht's user avatar
  • 69
0 votes
0 answers
1k views

Slow read speed in ZFS mirror (slower than write speed, and very slow for small chunk sizes)

I have a server running debian on top of a ZFS 3-way mirror of Exos X18 18TB (ST18000NM001J). I'm benchmarking it and I'm finding some surprises for the read rate under certain conditions. But first, ...
Héctor's user avatar
  • 141
0 votes
1 answer
458 views

How ZFS avoids inodes' number exhaustion and why wasn't it implemented in previous filesystems (e.g. ext4)?

Chapter 1 of Oracle's ZFS Guide states that all metadata is allocated dynamically, so no need exists to preallocate inodes which was a positive surprise, but makes me wonder why the methods ZFS uses ...
Daniel Krajnik's user avatar
2 votes
1 answer
74 views

ZFS: Replace raidz1-member of a striped pool for raidz2

I have a pool (in Ubuntu 20 LTS) like this: # zpool status pool: zpool_test state: ONLINE scan: none requested config: NAME STATE READ WRITE CKSUM zpool_test ONLINE 0 ...
JakeRoberts's user avatar
0 votes
0 answers
207 views

ZoL+FIO Randwrite nvme bs=8k@32io = 148MiB/s?

Sorry for the title, but it's very short summary of BS that I'm looking into. Situation I'm using ZoL 2.1.5 (from jonathonf's ppa) on Ubuntu (tried 20.04&22.04) I have following NVMe disk ...
Vladislav Losev's user avatar
0 votes
1 answer
2k views

How can I list what zfs compression algorithms are available?

I have a zfs pool on a production system and I would like to see if it's possible to use zstd compression instead of the current gzip setting. Is there any way to list available compression options?
yes's user avatar
  • 51
1 vote
1 answer
184 views

ZFS size discrepency between 2 very similar configurations

I have 20X sata 12TB disks in a file server with a Broadcom/LSI MegaRAID SAS39xx raid controller. It’s running ubuntu. For an performance experiment, I created two storage pools: -A single hardware ...
Thingomy's user avatar
1 vote
0 answers
639 views

On Linux ZFS Server - What is eating my memory?

Our monitoring tool regularly reports low memory for one of our servers running ZFS. # free -g total used free shared buff/cache available Mem: 125 ...
Hansjakobli's user avatar
2 votes
1 answer
485 views

ZFS disk with Postgresql fragmenting quickly with write-heavy application

I am running a write-heavy application where I am storing my Postgresql on ZFS. Generally, it works well, but I am finding that my ZFS pool is fragmenting heavily. I even created a new ZFS pool and ...
Jason's user avatar
  • 131
7 votes
1 answer
5k views

zfs: flush cache without exporting

For testing I need zfs' cache to be cold. I can flush caching from the pool by removing the cache disks, exporting and importing the pool. This gives the effect I want. But would really like not to ...
Ole Tange's user avatar
  • 3,136
0 votes
1 answer
598 views

Import a ZFS pool from a disk snapshot of another machine

I have a server on Azure with a disk mounted that contains a ZFS filesystem. I also have a snapshot of the disk (taken from Azure, not zfs snapshot) which I want to mount to a new server. The disk ...
Srujan Deshpande's user avatar
0 votes
1 answer
383 views

Zpool permanent error for raidz2

Problem: Zpool shows "errors: Permanent errors have been detected in the following files: tank/vms/fileserver:<0x0> Server has six 12Tb drives in a raidz2. These are spinning drives. Zpool ...
pender's user avatar
  • 1
0 votes
1 answer
1k views

Remove Missing Drives from ZFS Pool

After an embarrassing session trying to replace a disk in my ZFS pool, I have a bunch of entries representing disks that are no longer present in the system: NAME STATE READ ...
Danny Roberts's user avatar
1 vote
0 answers
251 views

ZFS/ZoL: Consequences of increasing zfs_vdev_async_read_min_active (and max)?

Vdev async read queues have min=1 and max=3 by default. All sync read/write queues are defaulted to min=max=10, while async writes get min=2 and max=10. Async reads are described as "prefetch ...
Tavin's user avatar
  • 111
0 votes
1 answer
273 views

Multipass mount folder on zfs file system - Source path does not exist

I am trying to add storage to an existing Multipass VM. I created a new ZFS filesystem, mounted locally at /zfs/morespace. Then tried to mount it with multipass mount /zfs/morespace existingvm:/mnt/...
wanderingcode's user avatar
1 vote
1 answer
429 views

ZFS send/recv full snapshot

I have been backing up my ZFS pool in Server A to Server B (backup server) via zfs send/recv, and using daily incremental snapshots. Due to hardware issues, the ZFS pool in Server A is now gone - and ...
LooseAlien123's user avatar
1 vote
2 answers
903 views

How can one recover/write a label (clone existing one)?

ZFS stores 4 labels, 2 at the beginning of a device, 2 at the end. When they are corrupted a pool cannot be mounted. I had a case of 3 broken labels (failed to unpack), but 1 was still intact. I could ...
cfi's user avatar
  • 258
3 votes
2 answers
6k views

Limiting ARC Size for the proposed system

I have a pool of 5 x enterprise 12Gps SSD that I use for internal storage for a proxmox server. This pool is used to stand up VMs and containers. The problem is that it is eating up a lot of my ...
Shery's user avatar
  • 141
2 votes
2 answers
173 views

Frozen boot due to slow disk/controller

Im running ubuntu 20.04 on dell r740xd, One of the disk controller seem to present the disk(multipath disks used for openzfs pool) slow while the server is booting. If the server is boot from '...
sherpaurgen's user avatar
1 vote
0 answers
381 views

ZFS disk error on write

our ZFS backup pool is producing strange disk errors when writing data. This pool is replicated via DRBD on a second server with identical hardware which is also experiencing the same errors. This is ...
Edgxxar's user avatar
  • 11
2 votes
1 answer
1k views

Recovering data from a zpool with a missing device

I have a zpool consisting of two mirrored drives, storing all my personal data. I wanted to add another mirror drive, since the other drives have been in use for several years now. Instead, I managed ...
soulmerge's user avatar
  • 161
0 votes
1 answer
508 views

Does zfs zfs recv validate checksums?

It seems that zfs send includes a checksum for all included data (stated for instance here). Is this checksum automatically verified by zfs recv? I would assume it is, but I cannot find any ...
joaerl's user avatar
  • 417
1 vote
1 answer
1k views

ZFS datasets wont mount after upgrade to ubuntu 21.10

So i recently upgraded from Ubuntu 21.04 to 21.10 and now my ZFS datasets wont mount, even manually using the forced option. I have tried exporting the pool and re-importing the pool, but even trying ...
nitrobass24's user avatar
5 votes
2 answers
7k views

Does it make sense to create a zpool with lots of mirror vdevs?

To prefix, I am rather new to ZFS. My goal is to create an internal NAS system, with minimal chance of losing all my data. I've currently acquired four 4TB disks, and I plan to run them in a single ...
MechMK1's user avatar
  • 346
0 votes
1 answer
985 views

Is there an advantage to using discreet ZFS datasets/filesystems in a single zpool?

I have a Centos server utilizing ZFS on Linux. The disks are in a single zpool. When you type in zfs list it shows a single filesystem(?)(dataset?), tank1. NAME USED AVAIL REFER ...
DrKumar's user avatar
  • 171
2 votes
3 answers
5k views

Erratic (terrible) Disk Performance I/O (Debian/Proxmox)

Summary I'm seeing dramatically fluctuating I/O performance on a ZFS SSD mirror in Proxmox VE 7 (Bullseye). I'm simply too much of a novice to be able to track it down on my own. Details This is VERY ...
paul's user avatar
  • 21
2 votes
2 answers
1k views

.zfs folder's missing, but snapshots are still there and mountable (inode trouble?)

$ sudo zfs list -t snapshot | grep childDataset3 a whole bunch are listed as expected (e.g. pool/dataset/childDataset3@today) $ ls /pool/dataset/childDataset3/.zfs ls: cannot access '/pool/dataset/...
S Hunter Simpson's user avatar

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