SCSI device targets mapping to mirror devices

[Bob S]

I just compiled and loaded zfs-fuse on a test (for now) CentOS 5.8 machine.
It compiled and set up just fine.  The actually install instructions were a bit lite.
I had to add an lsmod test and a "modprobe fuse " in the startup script to get it to
come up correctly.  The names of the files in the contrib folder showed where
they would go, but a writeup would be good.  I will post my notes when I am
happy that it comes up clean.

My question deals with the mirror drives and the actual scsi devices.
I attached a scsi array that takes up to 12 disks through a scsi card.
I happened to choose the slots mapping to targets 2, 4, 10, and 12.
These ended up as /dev/sda, /dev/sdb, /dev/sdc, and /dev/sdd.
I created a pool with:
zpool create -f zfspool mirror sda sdc
zpool add -f zfspool mirror sdb sdd

My concern is that if I drop in more drives, the /dev/sd* values could get
swapped around.  This would make things very ugly for zfs.
On other scsi linux systems I use the LABEL parameters to mount drives
and not worry about device mappings.

I use ZFS on Solaris regularly, on that system the commands look like
zpool create -f zfspool mirror c0t2d0 c0t10do
zpool add -f zfspool mirror c0t4d0 c0t12d0
In this case, unless I put the drive in the wrong slot, the mapping will always work.

Does anyone have any experience with this sort of setup?

Is there documentation which I have not stumbled across which describes how to
handle this sort of situation?

Thanks in advance for any replies
Bob

[Fajar A. Nugraha]

On Fri, Nov 2, 2012 at 8:52 PM, Bob S <robert...@alcatel-lucent.com> wrote:
> I had to add an lsmod test and a "modprobe fuse " in the startup script to

lsmod shouldn't be necessary. modprobe-ing a loaded module will return sucess.

Or, just put fuse in /etc/modules to get it always loaded.

> a writeup would be good.

The thing is I don't think anyone is maintaining zfs-fuse anymore.

> My concern is that if I drop in more drives, the /dev/sd* values could get
> swapped around. This would make things very ugly for zfs.
> On other scsi linux systems I use the LABEL parameters to mount drives
> and not worry about device mappings.
>
> I use ZFS on Solaris regularly, on that system the commands look like
> zpool create -f zfspool mirror c0t2d0 c0t10do
> zpool add -f zfspool mirror c0t4d0 c0t12d0
> In this case, unless I put the drive in the wrong slot, the mapping will
> always work.
>
> Does anyone have any experience with this sort of setup?
>
> Is there documentation which I have not stumbled across which describes how
> to
> handle this sort of situation?

From the other related project:
http://zfsonlinux.org/faq.html#WhatDevNamesShouldIUseWhenCreatingMyPool

The first three should apply to zfs-fuse as well.

--
Fajar

[Bob S]

Thanks a bunch Fajar,  The link tells me what I need to know.
I think I will look into the other project.

 If zfs-fuse is no longer supported, It might be good if there was a
reference to a version that is supported. 

Thanks again for the help

Bob

[Emmanuel Anne]

No longer maintained is the right way to say it, it has no official maintainers anymore. I fixed a bug to my repository lately though, one reported by someone who will maybe try to merge the latest patches from Illumos.

Except that well 0.7.x is the last official version, and there are still a bunch of patches from my repository which were never merged to the official version but that I have been using for 1 year without problem. So it just works.

2012/11/2 Bob S <robert...@alcatel-lucent.com>

Bob

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