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Thread: ZFS, samba, acls

  1. #1
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    Mar 2006
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    ZFS, samba, acls

    Hi. I'm not sure if this is very ambitious or has already been done.
    I want to create a file server to serve a windows only environment based on Samba. It needs to have volume shadow copies, which I believe can be easily done in either lvm, btrfs or zfs (maybe more), but also windows full acl support. This works fine with the acl_xattr vfs module but I've read that it's not quite that straightforward if using, for example, ZFS. There's a thread here on acls :
    https://github.com/zfsonlinux/zfs/issues/170
    At the end, a patch has been submitted - does this mean that it should work, has anyone experience with it, and what samba vfs module should I use, and what zfs settings should I set (if using zfs).
    OR should I use btrfs? I'm not sure if it's still considered experimental, and that would make me nervous with 5000 people's files (work in a hospital).

    The reasoning behind zfs / btrfs is that it's still rather hard, in my estimation, to extend the size of an lvm volume group - you can extend the partition of a physical disk underneath and create another partition, then add to the PV and VG, but it seems more tricky than even a basic resize of a native ext4 partition using fdisk, partprobe and resize2fs - but then I can't do snapshots!

    Anyway, any thought gratefully accepted!
    Andy

  2. #2
    Join Date
    Aug 2009
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    Makati City, Philippines
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    2,269
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    Xubuntu 16.04 Xenial Xerus

    Re: ZFS, samba, acls

    Maybe you can specify more of your requirements and then we can think of the possible architecture alternatives.
    Why do you need ACLs?
    Shadow copies means snapshots right?
    How do the 5000 people access their files?

  3. #3
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    Re: ZFS, samba, acls

    Hi,
    So the 5000 people access their files via smb at the moment - a mixture of people's office documents, some server backups, windows roaming profiles and so on.
    I want to replace an aging windows 2008 storage server we are having issues with, either with another windows box (not keen because we have quite a few issues with performance and the OS being 2008 (not R2).
    The easiest thing would be to move to 2012 but since MS axed storage server, we need cals for everyone even just to access their files - £15 * 5000 isn't a small amount.
    So on windows we use volume shadow copies (previous versions) to get back recent files, then retrieve any older stuff from the equallogic sans we have via it's replication or snapshotting which is a longer process.
    I wanted to set up a Samba server that would do the same job, and support full windows acls - some of our departmental level shares are very complicated in terms of acls and posix acls just wouldn't work.
    At the moment with an ext4 file system this means using the acl_xattr or acl_tdb modules, which is fine, but quite a common occurrence is that we need to extend the volumes as things get bigger, with windows it's very easy in the disk management snap-in and we'd need it to be as easy in ubuntu, which it can be, but the snapshot requirements complicate things meaning we need to use lvm to get the snapshot. The tricky thing then is that giving more partition space to an lvm volume group isn't as easy as just extending a flat file system, you need to create another parition in the extra free space and then tie it to the VG. It just seems messier than it needs to be.
    So .. I was looking at other file systems that can do in-volume snapshots, resize on the fly without an lvm type system and that hopefully support the extended windows acls we require. ZFS seems to fit in terms of it's flexibility as a file system but I'm not sure if the support for samba is quite as good in terms of acl support. The thread I posted seemed to indicate it might be ok now but it's not clear how i would go about settings it up.
    Then, btrfs - is experimental. Perhaps not the best for a production system..
    and the other alternative is using BSD I guess.
    Any ideas?!
    Thanks

  4. #4
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    Re: ZFS, samba, acls

    ZFS on Linux would fit the bill. It supports POSIX ACLs, is easily expandable, copy on write so it has snapshots (can be configured to work as shadow copies), and is stable.

  5. #5
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    Mar 2006
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    Re: ZFS, samba, acls

    Ok.. I'm with it on most of the points .. but it doesn't (afaik) support full windows acls via filesystem attrs .. or does it?
    I definitely need more than posix acls, which are just not going to fit the bill.

  6. #6
    Join Date
    May 2008
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    Ubuntu 14.04 Trusty Tahr

    Re: ZFS, samba, acls

    Quote Originally Posted by frankerooney View Post
    Ok.. I'm with it on most of the points .. but it doesn't (afaik) support full windows acls via filesystem attrs .. or does it?
    I definitely need more than posix acls, which are just not going to fit the bill.
    Window's style ACL's are supported by both EXT and ZFS. ZFS and LVM provide the ability for shadow copies. Both of these are directly addressed by Samba VFS modules. In other words both the FS's have the ability to respond to these Windows features because Samba provides them. You can use LVM for the same reason. LVM/EXT is the same concept as ZFS. LVM provides the partition abstraction and EXT provides the FS. ZFS provides both the partition and the FS. Both understand Samba VFS modules.

    See here for ZFS and Samba VFS.
    See here for LVM and shadow copies.
    See here for general Samba shadow copy information.
    -BAB1

  7. #7
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    Re: ZFS, samba, acls

    ZFS looks good but I'd read that on linux it didn't have the extended filesystem attributes needed for complete acl support. I did read something about a setting "zfs set xattr=sa" but it's certainly not widely documented and one post cited issues with corruption.
    I'm not willing to use acl_tdb, which is theory should work with any filesystem, just because this thing needs to scale.
    I have also looked at maybe doing a cluster with cdtb, but am unclear whether it strictly needs a clustered filesystem underneath, or whether I could just use the cdtb to manage the cluster locking and export an iscsi san volume to all of the nodes. Surely if samba is doing the file locking, then there shouldn't be any issues there?
    Anyway, I looked at ceph (seems to have poor performance), ocfs2 (snapshots are only at file level, designed for vms rather than cifs, where I'd want to export a whole folder/subfolder structure for snapshots), gpfs (proprietry, not free - needs to be really so I can do the research in the first place), glusterfs (no snapshots), lustre (lvm snapshots, with their performance problems and awkwardness).
    This is a minefield!
    Any more suggestions on the cluster bit? Or should I just zfs and take the plunge?

  8. #8
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    Mar 2006
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    Re: ZFS, samba, acls

    .. Anybody done a ctdb cluster? What filesystem did they use? Did snapshots and resizing work ok? I guess I couldn't just deliver our shared iscsi storage to multiple hosts and get ctdb to do the locking because of the snapshots i.e. quiescing the filesystem on one host when another has no idea this is being done..
    Thanks

  9. #9
    Join Date
    Apr 2008
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    Re: ZFS, samba, acls

    Hi! I'm trying to setup samba on zfs but getting errors about no ACLs on the filesystem. I set aclinherit=passthrough and acltype=posixacl but it still doesn't work. Is it possible at all to share ZFS volume via SAMBA on linux?
    Last edited by OnlyWhisky; March 15th, 2015 at 08:08 PM.

  10. #10
    Join Date
    Oct 2010
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    Re: ZFS, samba, acls

    Quote Originally Posted by OnlyWhisky View Post
    Hi! I'm trying to setup samba on zfs but getting errors about no ACLs on the filesystem. I set aclinherit=passthrough and acltype=posixacl but it still doesn't work. Is it possible at all to share ZFS volume via SAMBA on linux?
    Yes, I am currently doing this, what is your problem?

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