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12

Don't go down the road of breaking the ZFS array to "rotate" disks offsite. As you've seen, the rebuild time is high and the resilvering process will read/verify the used size of the dataset. If you have the ability, snapshots and sending data to a remote system is a clean, non-intrusive approach. I suppose you could go through the process of having a ...


9

Yes, it all works... Dedupe, compression, checksumming, caching are all present when using zvols in ZFS. But I really prefer NFS for virtualization purposes because of the transparency. But either will do the job. Can you elaborate a bit more on your intended use for ZFS? I ask because there are a lot of potential design/planning issues. Take a good read ...


6

ZFS pool information is not stored in a plain text file. Information about a pool is stored on the disks themselves. ZFS pool information can also be written to a ZFS cache file, but it does not contain mount point information. If you want to get mount point values for your ZFS pools you can use the following: zfs get mountpoint <pool name> zfs get ...


6

RAIDZ2 isn't going to be especially fast with 4 SATA disks... on a server with 4GB of RAM... with a weak processor... and without any level of ZFS tuning. ZFS mirrors would have been a better choice for a few reasons as well. However, have you measured actually filesystem performance? What are you expecting to see? That's about right, based on the gear ...


6

I use ZFS on Linux as a volume manager and a means to provide additional protections and functionality to traditional filesystems. This includes bringing block-level snapshots, replication, deduplication, compression and advanced caching to the XFS or ext4 filesystems. See: https://pthree.org/2012/12/21/zfs-administration-part-xiv-zvols/ for another ...


6

$ sudo find /lib/modules/$(uname -r)/updates -name "splat.ko" -or -name "zcommon.ko" -or -name "zpios.ko" -or -name "spl.ko" -or -name "zavl.ko" -or -name "zfs.ko" -or -name "znvpair.ko" -or -name "zunicode.ko" | xargs rm -f $ sudo apt-get install --reinstall ubuntu-zfs $ sudo apt-get install --reinstall $(dpkg-query --show --showformat='${binary:Package}\n' ...


6

You shouldn't use non-ECC RAM on any machine that is storing or processing data you care about. This is not something that is unique to ZFS. You're right, ZFS devs have gone to great lengths to add many layers of hashing, verification, etc. to the filesystem - all of these are of massive help in ensuring data integrity, and all of these efforts can be ...


6

OH MY! How embarrassing ... I found the reason ... The pool (old-pool) I am trying to replicate is itself a backup store, receiving regular updates via zfs receive -F So while my recursive snapshot was initially complete, it got "cleaned out" as new snapshots were being integrated into individual filesets. Once I stopped the backup script that was ...


5

Copy the data. That is all. There's a bunch of missing output in your examples, but it doesn't matter. The only thing you need to do to move data into a compressed filesystem is to rewrite the data either by copying it, moving it or populating a new filesystem. Avoid the problem in future situations by enabling compression at the pool level so that it's ...


5

This came up in discussion on the ZFS mailing list. The kernel ABI changed between 0.6.2 and 0.6.3 in such a way that 0.6.3 user-land tools can't interact with 0.6.2 kernel modules, which is the configuration after upgrading to 0.6.3. According to numerous messages on this list, the right approach is simply to reboot. This is covered in the ZFS ...


5

That looks like...a bug. In fact, it is a bug. The ZFS userland is updated, but the kernel modules aren't being updated by DKMS. This assertion is caused by the version mismatch. You can work around it by a process given in a comment to the bug, by removing the old kernel modules and then reinstalling everything. $ find /lib/modules/$(uname -r)/extra -name ...


5

The explanation for the JBOD resiliency you read about on the mailing list is probably something like a set of RAIDZ3 vdevs and enclosures... Say 8 disks per RAIDZ3 (5+3), and 5 (or 8?) enclosures, such that the vdevs were comprised of a single disk from each enclosure. But for realz, I would not do 1PB of storage without some degree of ...


5

Yes, it's still the convention, and yes, it holds true even as you scale. With ZFS, in fact, you really don't want to get to the 75% mark in your zpool too often. Fragmentation, snapshots and general performance tend to be impacted. If building anew, don't start with anything more than 40% utilization and be sure to plan for growth.


4

If you ever end up on this page and your running Debian, you only have to do the following to fix the issue: # apt-get update # apt-get dist-upgrade # reboot The issue occurred because a simple update doesn't not replace old library files with the newer ones. This is why a dist-upgrade is needed. From the apt-get manpage: dist-upgrade in addition to ...


4

On ZFS On Linux, starting with version 0.6.3 this can be handled quite elegantly by using the ZFS Event Daemon (zed). The event daemon, by virtue of monitoring the kernel events directly, can react almost immediately to any events that take place and does not depend on continuous polling and parsing of some other command's output. Create a shell script with ...


4

As Gene points out, the list of file systems (not partitions!) in a ZFS pool is stored within the pool itself. Specifically, it is stored as a part of the pool metadata, which is not easily accessible in raw form. You can access the metadata using zdb (the ZFS debugger tool), but you need to be careful as well as have some familiarity with the ZFS on-disk ...


4

This is a bad idea... Sometimes it makes sense to use ZFS with hardware RAID, or a combination of ZFS and hardware RAID. This is one of those cases. The main issue you'll encounter doing this the way you're planning is that each single disk will be its own VDISK and have its own MSA RAID metadata. The failure of a disk means that the VDISK is completely ...


4

After further experimentation I've found a fair solution, however it comes with a significant trade-off. Disks which have been offline'd but not detached can later be brought back online with only an incremental resilvering operation ("When a device is brought online, any data that has been written to the pool is resynchronized with the newly available ...


4

The problem is zfs's error correction features (checksum & scrub) can potentially result in a total loss of data on a memory corruption error as opposed to say xfs which will happily write your error to disk in just the affected block(s).


4

I'm using ZFS with non-ECC RAM. Widely enough. I'm not writing this to say it's safe. However, for several years I didn't see zfs corruption yet. Furthermore, when using zfs on ancient hardware, I saw all sort of memory problems, even an inability to boot up. From my experience - you will encounter all sorts of fatal kernel traps faster than the zfs data ...


4

Don't focus on snapshots. It's clouding your judgment :) VMware has templating and cloning functionality built into vCenter. You need a $600 vSphere Essentials license to enable this. You can create a VM to your taste, then clone it to a template. That template can then be used to generate new virtual machines. This allows you to have a "clean state" but ...


4

The VMware compatibility guide includes a comprehensive storage section that lists the supported storage solutions and provides details on what features are available for each listing. You can also filter the search results by the features. After locating a listing you can drill-down into it to see the details. You should be looking for arrays that support ...


4

Yes. vStorage APIs for Array Integration http://kb.vmware.com/selfservice/microsites/search.do?language=en_US&cmd=displayKC&externalId=1021976 Check the HCL for Storage. OmniOS isn't a listed partner. NetApp is.


4

ZFS is very resilient. The most basic example of shipping a file system would be: # zfs snapshot tank/test@tuesday # zfs send tank/test@tuesday | ssh user@server.example.com "zfs receive pool/test" Note the snapshot prior to the send (and sending the snapshot). You could wrap that up into a script to delete the local snapshot after you've sent it to the ...


4

I'm not familiar enough with NFS to know what specific locking issues you may be referencing, but I generally hear that OpenAFS works better with whole-file locks, yes. However, OpenAFS does not work well with byte-range locks across different machines (that is, locking certain byte ranges in a file, as opposed to locking entire files). If you are only ...


3

More modern versions of ZFS provide a command named zstreamdump which can provide human-readable information from a stream (or image) created using zfs send. This is an example using the commandline: host # zstreamdump < foo.zfs BEGIN record ... toname = zpool/data/foo@04hoursago END checksum = ...


3

Note: using a hot spare in this situation probably is not the best idea. See below for the reasoning behind that, below the answer to the question as asked. The answer to the question as asked: Before reducing the pool redundancy, I strongly suggest letting one complete scrub run to ensure that all devices are functioning and that there are no latent ...


3

I'd use SAS in just about every case, unless this is a home system that won't be running production workloads. It's less about speed and more about error correction, the protocol and reliability of the entire system.


3

Don't use NexentaStor for new installations in 2015. It's a dead product!! You could post a support question on their forums (good luck), but the community user base was basically abandoned and there are simply better alternatives for a ZFS storage appliance. The main reason to consider this advice is hardware support. Linux and other actively-developed ...


3

The statement that RAIDZ-1 is "not good enough for real world failures" is because you are likely to have a latent media error on one of your surviving disks when reconstruction time comes. The same logic applies to RAID5. Before we go into specifics, consider your use case. Are you storing photos, MP3's and DVD rips? If so, you might not care whether ...



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