[NCLUG] Installing ubuntu 12.04 to ZFS root directory

[Jesse Griffin]

Hello,

I think you are crazy to be using RAIDZ2 with only 4 drives!  A RAID10 setup
would give you way better read performance and essentially the same redundancy.
 A basic RAID10 sort of mirrored pool can be created like this:

    zpool create tank0 mirror sda sdb mirror sdc sdd

Compression at the default recommended level should actually increase your
throughput.  This is because less data is stored on disk and your CPU can
decompress the data faster than your mechanical disk could serve it up.  Of
course, this assumes that your data set has at least an average level of
compressibility.

Though related the Solaris, there is lots of good information here,
http://www.solarisinternals.com/wiki/index.php/ZFS_Best_Practices_Guide, if you
haven't come across that yet.


Thank you,
Jesse Griffin
tummy.com, ltd.

On 08/19/2013 01:43 PM, Phil Marsh wrote:
> 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
>>
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