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The State of ZFS on Linux

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Re: The State of ZFS on Linux

#61

Post by justizin »

michael_h wrote: post #43
mbreese wrote: post #41

I love ZFS, and I love working with Linux, but I can't help but worry about using ZFS on Linux. Without the needed support from the kernel side, I don't see how it can be useful for production. I can see using it on personal workstations, but for any situation where data loss is critical, you just won't see any uptake. Because of the licensing, ZFS can never be anything more than a second-class citizen on Linux. That…

Without the needed support from the kernel side Can you clarify what you mean by that?

The previous poster clearly does not understand that ZFS on Linux is essentially a native port with very careful dancing around licensing borders.

Re: The State of ZFS on Linux

#62

Post by ryao »

nisa wrote: post #59
ryao wrote: post #52

Earlier quoted context omitted.

Below are a few remarks: To expand on your LZ4 comment, LZ4 is 3 times faster than LZO at decompression: https://code.google.com/p/lz4/ However, LZ4's real innovation is on incompressible data. I do not have a reference at the moment, but there have been benchmarks on the userland lz4 tool on incompressible data that show it processing 10GB/sec. This is because LZ4 uses a hash table that enables it to give up when tr…

Wow! Thanks for your reply. I've experienced some minor issues with severe broken disks where the SPL layer discards the disk but the zpool is still online. It's not a major issue and I've yet to encounter the issue again I've already filed a related bug: https://github.com/zfsonlinux/zfs/issues/2508 but I'm not an expert. If I can gather more data I'll try to submit as much data and hints I can find. As for cgroups…

I am also a Linux kernel contributor, so running the latest kernels is important for me. This prompted me to switch from Nvidia graphics to Intel graphics a couple of months ago. ZoL's future kernel version support should reflect this.

As for the issues you linked, the project will likely not be able to tackle them until next year, but being in the tracker means that they will receive attention.

Re: The State of ZFS on Linux

#63

Post by ryao »

gnu8 wrote: post #27
ryao wrote: post #11

Earlier quoted context omitted.

This is because Martin Matuška of FreeBSD has been focused on upstreaming changes made in FreeBSD's ZFS port into Illumos. At present, the ZFSOnLinux project has had no one dedicated to that task and code changes mostly flow from Illumos to Linux. This is starting to change. A small change went upstream to Illumos earlier this year and more should follow in the future. That being said, there are commonalities between…

I'm interested in point 2, can you clarify how and why Linux in-kernel virtual memory is crippled or provide a link?

There are two issues:

1. Page table allocations use GFP_KERNEL, even when done for an allocation that used GFP_ATOMIC. This means that allocations that are needed to do pageout and other things to free memory can deadlock. There is a workaround in the SPL that will switch it to kmalloc when this issue occurs. There is also a new mechanism in Linux 3.9 and later that should render this unnecessary.

2. The kernel deals with kernel virtual address space exhaustion in vmalloc() by spinning until memory becomes available. This is not a problem on current 64-bit systems where the virtual address space used by vmalloc is larger than physical memory, but it is a problem on most 32-bit systems.

Re: The State of ZFS on Linux

#64

Post by rodgerd »

DiabloD3 wrote: post #25

I've used ZoL since it was created, and zfs-fuse before that. I ran it on my workstation for a few years (managing a 4x750gb RAID-Z (= ZFS's RAID-5 impl), with ext3 on mdadm RAID 1 2x400gb root), and then swapped to BTRFS for 2x2TB BTRFS native RAID 1 (which was Oracle's ZFS competitor that seems to be largely abandoned although I see commits in the kernel changelog periodically), and now back to ZFS on a dedicated f…

> (which was Oracle's ZFS competitor that seems to be largely abandoned although I see commits in the kernel changelog periodically)

Under heavy development, officially supported by most of the major commercial distros, and still designated by Linus as the ext* replacement as the standard Linux filesystem.

Re: The State of ZFS on Linux

#65

Post by feld »

bussiere wrote: post #20

I may have read the article too fast , but what about cryptography in zol ? is there a way to crypt data on zol ? regards and thks for the article

Oracle extended ZFS to be able to encrypt specific filesystems, but this method has been heavily scrutinized for being susceptible to watermarking attacks

Re: The State of ZFS on Linux

#66

Post by ryao »

ashayh wrote: post #58

ZFS, and most* other file systems are all about _one_ computer system. While ZFS data integrity features may be useful, they don't prevent the wide variety of things that can go wrong on a _single_ computer. You still need site redundancy, multiple physical copies, recovery from user errors etc. Large, modern enterprises are better off keeping data on application layer "filesystems" or databases, since they can more…

The Lustre filesystem is able to use ZFSOnLinux for its OSDs. This gives it end to end checksum capabilities that I am told enabled the Lustre developers to catch buggy NIC drivers that were silently corrupting data.

Alternatively, there is a commercial Linux distribution called SoftNAS that implements a proprietary feature called snap replicate on top of ZFS send/recv. This is allows it to maintain backups across availability zones and is achieved by its custom management software running the zfs send/recv commands as per user requests.

In the interest of full disclosure, my 2014 income tax filing will include income from consulting fees that SoftNAS paid me to prioritize fixes for bugs that affected them. I received no money for such services in prior tax years.

Re: The State of ZFS on Linux

#67

Post by turrini »

I've created the script below a while (year) ago. It (deb)bootstrap a working Debian Wheezy with ZFS on root (rpool) using only 3 partitions: /boot(128M) swap(calculated automatically) rpool(according to # of your disks, mirrored or raidz'ed).

All commentaries are in Brazilian Portuguese. I didn't have time to translate it to English. Someone could do it and fill a push request.

https://github.com/turrini/scripts/blob/master/debian-zol.sh

Hope you like it.

Re: The State of ZFS on Linux

#68

Post by blumentopf »

feld wrote: post #65
bussiere wrote: post #20

I may have read the article too fast , but what about cryptography in zol ? is there a way to crypt data on zol ? regards and thks for the article

Oracle extended ZFS to be able to encrypt specific filesystems, but this method has been heavily scrutinized for being susceptible to watermarking attacks

Source? Edit: Found it.

http://lists.freebsd.org/pipermail/freebsd-hackers/2013-Sept...

Re: The State of ZFS on Linux

#69

Post by awonga »

I've looked into ZFS before for distributions like freenas, is there any solution on the horizon for the massive memory requirements?

For example, needing 8-16gb ram for something like a xTB home nas is high.

Re: The State of ZFS on Linux

#70

Post by mdellabitta »

DiabloD3 wrote: post #60
foobarqux wrote: post #33

Earlier quoted context omitted.

Can you speak more about why ZFS is better than BTRFS?

Working RAID 5 and 6, RAID "7" (Z3[1], triple parity, where Z/5 is single, and Z2/6 is dual), tiered RAID setups (such as JBOD'ed RAID-Z3s), zvols (as in, but not limited to, swap partitions in ZFS), more nuanced multi-controller and failover/spare setups, write-only journals (ZIL), second tier caching (L2ARC), LZ4 transparent compression, better designed snapshot and snapshot cloning support, more mature CLI tools,…

Re: [1], isn't that far too many drives in one RAIDZ? Referencing this: http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Prac...
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