[NCLUG] Installing ubuntu 12.04 to ZFS root directory

[Phil Marsh]

Hi, 
I had a question for those who tried ZFS. I am running ZFS RAIDZ2 with four 1TB drives, two are Seagate Barracudas and two are WD blacks. I am booting (MBR + /boot/grub from an older 500GB WD black and otherwise have the rest of the / and /home directories on a ZFS RAIDZ2 pool. My machine has 8GB 800MHz DDR2 RAM and an older quad core Intel (I think 6400 from 2007). The transfer rate of my SATA controllers is, I think, rated at 3GB/sec. The OS is Ubuntu 12.04 (64B)
My issue is that I'm noticing my booting is taking about 3x longer than my old Ubuntu 10.04 configuration (booted from a single drive with RAID 5 MDADM) and the machine winds up trying to access the floppy even though it's disabled for boot in the BIOS.
Software installation seems to be slow too.
Moreover, a check on iostat shows read BW of ~300K and write BW of about 3.5M. That seems slow to me.
I'm beginning to wonder if I should just go to MDADM (software) RAID6 for my /home?
Could someone kindly comment? Any suggestions and what is your experience with ZFS? Am I crazy to be using RAIDZ2 with four disks and the / directory for the most part, in the RAIDZ2?
Thanks,
Phil

Sent from my iPad

On Aug 18, 2013, at 5:33 PM, phil marsh <montanaembassy at yahoo.com> wrote:

> Hi folks,
> It finally sunk in what Bob was saying to me during the dinner of the last NCLUG meeting.
> I recall him saying that one could install GRUB and the /boot directory to an SSD which would need very little space.
> Next, one could install / and /home to a ZFS pool while having /boot and the MBR on an SSD.
> I went to: 
> https://github.com/zfsonlinux/pkg-zfs/wiki/HOWTO-install-Ubuntu-to-a-Native-ZFS-Root-Filesystem
> to find out how to install the /, with the exception of /boot which would be installed on a non-zfs filesystem,  and /home directories to a ZFS pool.
> Apparently, GRUB and the MBR have to still be installed outside of any ZFS pool to work properly?
> I have installed Ubuntu 12.04 to ZFS as described above and in the link. I did notice a few small errors (or differences between my and the author's system) namely, that one should not change the default /mnt/etc/network/interfaces file but instead leave it alone - I could not connect my network card after booting to the desktop GUI with the suggested changes.
> 
> Also, after installation, I had to update (add the standard repositories to) the /etc/apt/sources.list file and the /etc/apt/source.list.d directory in order to have all the standard repositories that one would have in a normal Ubuntu 12.04 desktop install.
> In order to do this, I was lucky to have a box that had Ubuntu 12.04 installed already but if you need, I can provide you my 
> /etc/apt/sources.list file and /etc/apt/source.list.d directory
> as well as a list of my installed packages.
> 
> My /boot directory and MBR now occupy a whole 500GB drive which is extremely wasteful to say the least!
> My questions are:
> 1. Can I move my /boot directory and MBR to a thumb drive which I will permanently place in one of the box's USB ports? I can apparently set the BIOS to boot from the USB (as for a USB live disk). I think this is possible and not too difficult but please comment if I'm mistaken.
> 2. Do you think this would be a good idea and also, would it give rise to problems later? I don't think the /boot directory sees many writes but again, I could be mistaken.
> Thanks so much,
> Phil
>