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The State of ZFS on Linux

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Re: The State of ZFS on Linux

#3
post #2

I am the author. Feel free to respond with questions. I will be watching for questions throughout the day.

I don't really have a question, but as a ZoL user I'd just like to say thanks for all the hard work.

It makes management of my disk arrays pretty painless and has some fantastic migration/recovery stuff going on. All of which I'm sure you know!

Re: The State of ZFS on Linux

#4
Great blog post! Something from personal experience. OpenZFS on FreeBSD feels mostly like a port of illumos ZFS where most of the non-FreeBSD-specific changes happen in illumos and then get ported downstream. On the other hand, OpenZFS on Linux feels like a fork. There is certainly a stream of changes from illumos, but there's a rather non-trivial amount of changes to the core code that happen in ZoL.

Re: The State of ZFS on Linux

#5
I'm using ZFS right now, because I need something that cares for data integrity, but the fact that it will never be included in Linux is a very big issue for me. Every time you upgrade your kernel, you have to upgrade the separate modules as well - this is the point where bad things can happen. I will definitely be looking into Btrfs once it is more reliable. For now I'm having a bit of a problem with SSD caching and performance, but don't care about it enough for it to be relevant, I just use the filesystem to store data safely and ZFS does an OK job.

Re: The State of ZFS on Linux

#6
post #5

I'm using ZFS right now, because I need something that cares for data integrity, but the fact that it will never be included in Linux is a very big issue for me. Every time you upgrade your kernel, you have to upgrade the separate modules as well - this is the point where bad things can happen. I will definitely be looking into Btrfs once it is more reliable. For now I'm having a bit of a problem with SSD caching and…

Out of curiosity, what distro are you using that's giving you problems? My Ubuntu box is humming along with no problems: kernel and ZFS updates happen at the same time.

Re: The State of ZFS on Linux

#7
post #3
post #2

I am the author. Feel free to respond with questions. I will be watching for questions throughout the day.

I don't really have a question, but as a ZoL user I'd just like to say thanks for all the hard work. It makes management of my disk arrays pretty painless and has some fantastic migration/recovery stuff going on. All of which I'm sure you know!

Seconded. ZFS is the only filesystem I trust with my children's baby pictures, as well as to store the git repo's for my personal projects (stuff I don't want on GitHub for a variety of reasons).

Re: The State of ZFS on Linux

#8
post #2

I am the author. Feel free to respond with questions. I will be watching for questions throughout the day.

Is there a plan at some point to include a daemon or a cron job to run automatic zpool scrubbing? I believe this was a feature that is available in other OSs' packages, but not currently with ZoL. Currently, I include two cronjobs, like so:

    18 * * * * /sbin/zpool list | grep ztank | grep ONLINE > /dev/null || /sbin/zpool status
    35 1 * * 4 /sbin/zpool scrub ztank
This way cron simply emails me if there are errors. However, I'd like a lot more communication from my storage array: if there are detected errors, I want to know right away.

My other question is much more specific to my case. Stupidly, I bought the Western Digital Green drives for my server (running in as a mirror of two drives). They are normally under no heavy load: just occasional file access to store/retrieve pictures, documents, or stream video. How likely am I to run into problems/should I replace these drives ASAP?

Re: The State of ZFS on Linux

#9
At a previous job, we built a proof-of-concept Sinatra service (i.e., HTTP/RESTful service) that would, on a certain API call, clone from a specified snapshot, and also create an iscsi target to that new clone. This was on OpenIndiana initially, then some other variant of that OS as a second attempt.

The client making the HTTP request was IPXE; so, every time the machine booted, you'd get yourself a flesh clone + iscsi target and we'd then mount that ISCSI target in IPXE, which would then hand off the ISCSI target to the OS and away you'd go.

The fundamental problem we hit was that there was a linear delay for every new clone; the delay seemed to be 'number of clones * .05 second' or so. This was on extremely fast hardware. It was the ZFS command to clone that was going to slowly.

Around 500 clones, we'd notice these 10/20 second delays. The reason that hurt so bad is that, to our understanding, it wasn't safe to do ZFS commands or ISCSI commands in a parallel manner; the Sinatra service was responsible for serializing all ZFS/ISCSI commands.

So my question to the author:

1) Does this 'delay per clones' ring familiar to you? Does ZFS on Linux have the same issue? It was a killer for us, and I found a thread eventually that implied it would not ever get fixed in Solaris-land.

2) Can you execute concurrent ZFS CLI commands on the OS? Or is that dangerous like we found it to be on Solaris?

Re: The State of ZFS on Linux

#10
post #5

I'm using ZFS right now, because I need something that cares for data integrity, but the fact that it will never be included in Linux is a very big issue for me. Every time you upgrade your kernel, you have to upgrade the separate modules as well - this is the point where bad things can happen. I will definitely be looking into Btrfs once it is more reliable. For now I'm having a bit of a problem with SSD caching and…

From what I understand, aside from certain RAID levels, btrfs is production-ready. RAID5 and RAID6 don't have recovery code finished yet, but RAID0, RAID1, "dup" which just keeps 2 copies of each chunk, and "single" mode all work fine.
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