Topic: ZFS (including ZFS on Linux)

This collects most or all of the entries I've written on ZFS and ZFS on Linux, in reverse chronological order; these cover a variety of ZFS topics, including a fair amount about the on-disk organization. You can also see the overall index of entries (or the chronological index).

2021-12-01: Unfortunately, damaged ZFS filesystems can be more or less unrepairable
2021-08-30: How ZFS stores symbolic links on disk
2021-08-29: Some notes on OpenZFS's new 'draid' vdev redundancy type
2021-07-25: The tiny irritation of ZFS's 'zpool status' nagging you about upgrades
2021-06-20: A bit on ZFS's coming raidz expansion and ZFS DVAs
2021-05-09: Storing ZFS send streams is not a good backup method
2021-04-14: Some things on ZFS (on Linux) per-dataset basic IO statistics
2021-04-02: ZFS on Linux is improving the handling of disk names on import
2021-03-06: Some views and notes on ZFS deduplication today
2021-02-19: ZFS pool partial (selective) feature upgrades are coming in OpenZFS
2021-02-15: How ZFS on Linux brings up pools and filesystems at boot under systemd
2021-01-24: Thinking through what can go badly with databases on ZFS
2021-01-21: A lingering sign of old hopes for ZFS deduplication
2020-12-21: The legibility of different versions of ZFS
2020-08-26: Even on SSDs, ongoing activity can slow down ZFS scrubs drastically
2020-07-28: Our ZFS spares handling system for ZFS on Linux
2020-07-26: Keeping backup ZFS on Linux kernel modules around
2020-07-19: In praise of ZFS On Linux's ZED 'ZFS Event Daemon'
2020-07-01: In ZFS, your filesystem layout needs to reflect some of your administrative structure
2020-06-30: The unfortunate limitation in ZFS filesystem quotas and refquota
2020-05-10: How we guarantee there's always some free space in our ZFS pools
2020-05-08: Revisiting what the ZFS recordsize is and what it does
2020-04-12: ZFS on Linux has now become the OpenZFS ZFS implementation
2020-04-10: 'Deduplicated' ZFS send streams are now deprecated and on the way out
2020-03-23: How we set up our ZFS filesystem hierarchy in our ZFS pools
2020-02-12: You can't delegate a ZFS administration permission to delete only snapshots
2020-02-10: Doing frequent ZFS scrubs lets you discover problems close to when they happened
2020-02-02: What we do to enable us to grow our ZFS pools over time
2020-01-29: Some effects of the ZFS DVA format on data layout and growing ZFS pools
Why ZFS is not good at growing and reshaping pools (or shrinking them)
2019-12-20: Splitting a mirrored ZFS pool in ZFS on Linux
2019-10-10: Some additional information on ZFS performance as you approach quota limits
2019-09-30: ZFS performance really does degrade as you approach quota limits
2019-08-30: ZFS is not a universal filesystem that is always good for all workloads
2019-07-26: Some things on the GUID checksum in ZFS pool uberblocks
How 'zpool import' generates its view of a pool's configuration
2019-07-24: ZFS pool imports happen in two stages of pool configuration processing
2019-07-15: ZFS on Linux still has annoying issues with ARC size
2019-05-31: Some things on how ZFS dnode object IDs are allocated (which is not sequentially)
2019-04-07: A ZFS resilver can be almost as good as a scrub, but not quite
2019-04-05: I won't be trying out ZFS's new TRIM support for a while
2019-04-01: Our plan for handling TRIM'ing our ZFS fileserver SSDs
2019-03-31: Our likely ZFS fileserver upgrade plans (as of March 2019)
2019-03-24: A bit more on ZFS's per-pool performance statistics
2019-03-19: ZFS Encryption is still under development (as of March 2019)
2019-02-09: 'Scanned' versus 'issued' numbers for ZFS scrubs (and resilvers)
2019-01-30: ZFS On Linux's kernel modules issues are not like NVidia's
2019-01-28: The potential risk to ZFS created by the shift in its userbase
2019-01-19: A surprise potential gotcha with sharenfs in ZFS on Linux
2019-01-13: Two views of ZFS's GPL-incompatibility and the Linux kernel
The risk that comes from ZFS on Linux not being GPL-compatible
2019-01-05: Some things on ZFS's per-pool performance statistics
2018-12-31: Our Linux ZFS fileservers work much like to our OmniOS ones
2018-12-30: Our third generation ZFS fileservers and their setup
2018-12-24: Some notes on ZFS prefetch related stats
2018-12-20: FreeBSD ZFS will be changing to be based on ZFS on Linux
2018-12-05: Some basic ZFS ARC statistics and prefetching
2018-10-24: You can sort of use zdb as a substitute for a proper ZFS fsck
2018-10-23: ZFS scrubs check (much) less than you probably think they do
2018-09-28: Using a very old ZFS filesystem can give you a kernel panic on Linux
2018-09-14: How you migrate ZFS filesystems matters
2018-09-04: ZFS quietly discards all-zero blocks, but only sometimes
2018-08-26: A little bit of the one-time MacOS version still lingers in ZFS
How ZFS maintains file type information in directories
2018-07-29: Our ZFS fileservers aren't happy when you do NFS writes to a full filesystem
2018-07-21: How we're handling NFS exports for our ZFS on Linux systems
2018-07-15: Understanding ZFS System Attributes
2018-07-13: ZFS on Linux's sharenfs problem (of what you can and can't put in it)
2018-06-29: How ZFS makes things like 'zfs diff' report filenames efficiently
2018-06-24: What ZFS block pointers are and what's in them
A broad overview of how ZFS is structured on disk
2018-06-22: When you make changes, ZFS updates much less stuff than I thought
2018-06-09: What ZFS messages about 'permanent errors in <0x95>:<0x0>' mean
2018-06-04: The superficial versus deep appeal of ZFS
2018-05-27: ZFS pushes file renamings and other metadata changes to disk quite promptly
2018-05-18: ZFS spare-N spare vdevs in your pool are mirror vdevs
2018-05-12: ZFS on Linux's development version now has much better pool recovery for damaged pools
2018-05-02: An interaction of low ZFS recordsize, compression, and advanced format disks
2018-04-23: ZFS's recordsize as an honest way of keeping checksum overhead down
2018-04-22: Thinking about why ZFS only does IO in recordsize blocks, even random IO
2018-03-19: Some exciting ZFS features that are in OmniOS CE's (near) future
2018-03-17: Much better ZFS pool recovery is coming (in open source ZFS)
2018-02-14: Some things about ZFS block allocation and ZFS (file) record sizes
2018-02-04: A surprise in how ZFS grows a file's record size (at least for me)
2018-01-06: What ZFS gang blocks are and why they exist
2018-01-05: Confirming the behavior of file block sizes in ZFS
2017-12-30: Some details of ZFS DVAs and what some of their fields store
2017-12-26: I continue to have strong confidence in ZFS On Linux
2017-11-25: Sequential scrubs and resilvers are coming for (open-source) ZFS
2017-09-27: ZFS's recordsize, holes in files, and partial blocks
2017-09-26: Using zdb to peer into how ZFS stores files on disk
2017-08-18: How ZFS on Linux names disks in ZFS pools
2017-08-16: The three different names ZFS stores for each vdev disk (on Illumos)
Things I do and don't know about how ZFS brings pools up during boot
2017-07-24: Trying to understand the ZFS l2arc_noprefetch tunable
2017-07-14: Link: ZFS Storage Overhead
2017-06-28: I don't think you should increase ZFS on Linux's write buffering
2017-06-14: The difference between ZFS scrubs and resilvers
2017-06-12: Resilvering multiple disks at once in a ZFS pool adds no real extra overhead
2017-05-07: ZFS's zfs receive has no error recovery and what that implies
A mistake I made when setting up my ZFS SSD pool on my home machine
2017-03-03: Some notes on ZFS per-user quotas and their interactions with NFS
2017-02-24: How ZFS bookmarks can work their magic with reasonable efficiency
2017-02-22: ZFS bookmarks and what they're good for
2017-01-13: The ZFS pool history log that's used by 'zpool history' has a size limit
2017-01-11: ZFS's potentially very useful 'zpool history -i' option
2017-01-02: ZFS may panic your system if you have an exceptionally slow IO
2016-12-20: In praise of zpool history
2016-11-23: We may have seen a ZFS checksum error be an early signal for later disk failure
2016-10-15: ZFS's 'panic on on-disk corruption' behavior is a serious flaw
2016-09-22: Why we've wound up without ZFS ZILs or L2ARCs on our pools
2016-08-26: Why ZFS L2ARC is probably not a good fit for our setup
2016-08-22: An interesting case of NFS traffic (probably) holding a ZFS snapshot busy
2016-08-07: The harm that comes from ZFS not being GPL-compatible
2016-06-19: Why ZFS can't really allow you to add disks to raidz vdevs
2016-06-17: Why you can't remove a device from a ZFS pool to shrink it
2016-06-15: ZFS on Linux has just fixed a long standing little annoyance
2016-03-14: An additional small detail of how writes work on ZFS raidzN pools
2016-01-21: One example of why I like ZFS on Linux
2016-01-20: Illumos's ZFS prefetching has recently become less superintelligent than it used to be
2016-01-11: The drawback of setting an explicit mount point for ZFS filesystems
2015-12-28: The limits of what ZFS scrubs check
2015-12-16: I just had another smooth Fedora version upgrade with ZFS on Linux
2015-12-05: The details behind zpool list's new fragmentation percentage
2015-12-02: What zpool list's new FRAG fragmentation percentage means
2015-11-14: ZFS pool import needs much better error messages
2015-10-09: How much space ZFS reserves in your pools varies across versions
2015-09-11: ZFS scrub rates, speeds, and how fast is fast
2015-09-10: Changing kernel tunables can drastically speed up ZFS scrubs
2015-09-06: Optimizing finding unowned files on our ZFS fileservers
2015-08-08: The ARC now seems to work right in ZFS on Linux
2015-08-07: One thing I now really want in ZFS: faster scrubs (and resilvers)
2015-05-17: A bit more on the ZFS delete queue and snapshots
2015-05-15: Your Illumos-based NFS fileserver may be 'leaking' deleted files
The ZFS delete queue: ZFS's solution to the pending delete problem
2015-03-08: Why ZFS's 'directory must be empty' mount restriction is sensible
2015-02-11: ZFS can apparently start NFS fileservice before boot finishes
2015-02-10: Our ZFS fileservers have a serious problem when pools hit quota limits
2015-01-25: The long term problem with ZFS on Linux is its license
2015-01-15: General ZFS pool shrinking will likely be coming to Illumos
2015-01-13: Our tradeoffs on ZFS ZIL SLOG devices for pools
2015-01-11: The effects of losing a ZFS ZIL SLOG device, as I understand them
2015-01-08: ZFS should be your choice today if you need an advanced filesystem on Unix
2015-01-05: Today on Linux, ZFS is your only real choice for an advanced filesystem
2014-12-29: How I have partitioning et al set up for ZFS On Linux
2014-12-27: My ZFS On Linux memory problem: competition from the page cache
2014-12-26: My experience with ZFS on Linux: it's worked pretty well for me
2014-10-31: With ZFS, rewriting a file in place might make you run out of space
2014-10-26: Things that can happen when (and as) your ZFS pool fills up
2014-10-25: The difference in available pool space between zfs list and zpool list
2014-08-03: Our second generation ZFS fileservers and their setup
2014-07-31: The temptation to rebuild my office machine with its data in ZFS on Linux
2014-07-30: Why I like ZFS in general
2014-06-27: A retrospective on our Solaris ZFS-based NFS fileservers (part 2)
2014-06-25: A retrospective on our Solaris ZFS-based NFS fileservers (part 1)
2014-05-21: How I wish ZFS pool importing could work
2014-05-02: An important addition to how ZFS deduplication works on the disk
2014-04-26: What I can see about how ZFS deduplication seems to work on disk
2014-04-02: I'm angry that ZFS still doesn't have an API
2014-03-31: I'm done with building tools around 'zpool status' output
2014-03-19: Why I like ZFS's zfs send and zfs receive
2014-03-05: ZFS's problem with boot time magic
2014-02-09: Why I want a solid ZFS implementation on Linux
2013-12-26: How ZFS scrubs routinely save us
2013-11-18: Why booting Linux from a ZFS root filesystem with GRUB can be hard
2013-11-04: How writes work on ZFS raidzN pools, with implications for 4k disks
2013-11-02: Revising our peculiar ZFS L2ARC trick
2013-10-18: ZFS uberblock rollback and the top level metadata change rate
2013-10-13: Revisiting some bits of ZFS's ZIL with separate log devices
2013-09-23: ZFS filesystem compression and quotas
2013-09-02: A little bit more on ZFS RAIDZ read performance
2013-08-16: SSDs may make ZFS raidz viable for general use
A peculiar use of ZFS L2ARC that we're planning
2013-07-11: The ZFS ZIL's optimizations for data writes
ZFS transaction groups and the ZFS Intent Log
2013-07-09: How we want to recover our ZFS pools from SAN outages
2013-07-05: ZFS deduplication is terribly documented
2013-06-25: Balancing Illumos against ZFS on Linux
2013-05-16: Why ZFS's CDDL license matters for ZFS on Linux
2013-05-08: Thoughts on when to replace disks in a ZFS pool
How ZFS resilvering saved us
2013-04-08: Why ZFS still needs an equivalent of fsck
2013-03-26: Reconsidering a ZFS root filesystem
2013-01-30: Thinking about FreeBSD versus Illumos for our ZFS fileservers
2012-12-24: Why we're almost certainly staying with ZFS
2012-11-02: Why our ZFS fileservers sometimes boot slowly
2012-10-31: Our DTrace scripts for NFS server, ZFS, and iSCSI initiator monitoring
2012-10-29: How ZFS file prefetching seems to work
2012-09-14: What determines how much work a ZFS resilver has to do
2012-08-04: Oracle, ZFS, and Linux (and Solaris)
2012-08-02: Can Oracle make ZFS much more attractive?
2012-07-31: Would GPL'ing ZFS have worked or been a good idea?
Ruminations on the future of ZFS
2012-07-14: ZFS's problem with generic messages
2012-05-22: Our pragmatic experiences with (ZFS) disk errors in our infrastructure
2012-04-28: ZFS and various sorts of read errors
2012-04-26: When we replace disks in our ZFS fileserver environment
2012-04-02: The problem of ZFS pool and filesystem version numbers
2012-03-31: Why I no longer believe that you need Solaris if you want ZFS
2012-03-12: Why ZFS log devices aren't likely to help us
2012-02-26: What information I want out of ZFS tools and libraries
2012-02-01: A ZFS pool scrub wish: suspending scrubs
2011-12-10: ZFS pool activation and iSCSI (part II)
2011-12-06: What I know about boot time ZFS pool activation (part I)
2011-11-13: A confession about our ZFS configuration
2011-10-29: Why ZFS dedup is not something we can use
2011-10-28: ZFS features that could entice us to upgrade Solaris versions
2011-07-20: Our ZFS spares handling system (part 3)
2011-07-04: Our ZFS spares handling system (part 2)
2011-06-29: Our ZFS spares handling system (part 1)
2011-06-23: The ZFS opacity problem and its effect on manageability
2011-05-11: How ZFS lets you recover from damaged metadata, and what the limitations are
2011-05-10: An important way to get ZFS metadata corruption
A brief summary of how ZFS updates (top-level) metadata
The different ways that you can lose a ZFS pool
2011-04-17: The ultimate (for now) answer for our ZFS ARC size problem
2011-02-25: Why I am not enthused about ZFS for my root filesystem
2010-10-24: Why we built our own ZFS spares handling system
2010-10-02: ZFS resilvers are a whole-pool activity
2010-08-29: How many uberblock copies ZFS writes on transaction group commits
2010-07-06: How zpool status reports on ZFS scrubs and resilvers
ZFS scrubs and resilvers are not sequential IO
2010-06-18: ZFS and multi-pool shared spares
2010-06-11: What I know about ZFS and disk write caches
2010-06-02: A ZFS feature wish: rewriting read errors
2010-05-28: Why I am really unhappy with ZFS right now: a ZFS import failure
2010-05-05: The right way to fix ZFS disk glitches (at least for us)
2010-04-05: An important thing about how ZFS handles spares
2009-11-21: An update on faulted ZFS spares
2009-10-12: ZFS GUIDs vs device names
2009-10-08: What is going on with faulted ZFS spares
2009-10-07: A brief introduction to ZFS (disk) GUIDs
2009-09-12: My opinions on when you should let ZFS handle RAID stuff
2009-09-11: Why you should let ZFS handle the RAID stuff
2009-09-10: What I know about how ZFS actually handles spare disks
2009-08-28: ZFS changes filesystem device numbers on reboot
2009-07-10: An unpleasant surprise about ZFS scrubbing in Solaris 10 U6
2009-05-15: Why df on an NFS-mounted ZFS filesystem can give odd results
2009-05-05: How we periodically scrub our ZFS pools
2009-04-16: What causes the ZFS file deletion problem with snapshots
2009-04-15: The problem with Solaris 10 update 6's ZFS failmode setting
2009-03-06: What can keep a ZFS pool busy and prevent it from exporting
2009-03-02: Some gotchas with ZFS in Solaris 10 update 6
2009-02-04: An alarming ZFS status message and what is usually going on with it
2009-02-01: Understanding ZFS cachefiles in Solaris 10 update 6
2009-01-26: My reaction to Solaris 10 update 6's ZFS changes
2009-01-17: Practical issues with getting ZFS on Linux
2008-12-30: ZFS and crazy dates
2008-11-05: An issue with quotas on ZFS pools
2008-10-27: What we keep track of for ZFS pools
2008-10-23: Another update to the ZFS excessive prefetching situation
2008-10-08: How we set up our Solaris ZFS-based NFS fileservers
2008-09-15: Why ZFS's raidz design decision is sensible (or at least rational)
2008-09-14: A read performance surprise with ZFS's raidz and raidz2
2008-09-12: ZFS's helpful attention to detail
2008-08-24: An update to the ZFS excessive prefetching situation
2008-08-04: Our answer to the ZFS SAN failover problem
2008-07-13: How ZFS helps out with the big RAID-5 problem
2008-06-12: The problem with ZFS, SANs, and failover
2008-06-03: My problem with ZFS
2008-05-17: Why we're interested in many ZFS pools
2008-05-13: Things I have learned about ZFS (and a Linux iSCSI target)
2008-04-21: Dear ZFS: please stop having your commands stall
2008-04-02: ZFS: Reservations versus quotas
2008-03-22: Why NFS writes to ZFS are sometimes (or often) slow
2008-03-02: How ZFS's version of RAID-5 can be better than normal RAID-5
2008-02-06: Why ZFS needs a zfsdump
2008-01-21: Why I believe that you want Solaris if you want ZFS
2008-01-13: The robot logic of ZFS snapshots and quotas
2007-11-25: Why we may not be able to use ZFS
2007-09-05: Features that I wish ZFS had
2007-08-01: A ZFS-based fileserver design
2007-06-25: ZFS's issues with long term storage management
2007-04-17: A disappointment with ZFS

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Last modified: Thu Sep 19 14:11:37 2019
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