A place to rant.

Sunday, August 20, 2006

Installing Nexenta Alpha 5 on Toshiba A75 laptop

Excited from my recently-completed internship on Sun's Solaris Kernel Group, and desperately needing to reinstall something on my Toshiba A75 laptop, I decided to go ahead and try installing Nexenta Alpha 5.

Why Nexenta?

I've been a Debian (or Debian-based-distro) user for a while. First I used stock Debian, but Kubuntu quickly became my distro-of-choice after I installed it over year ago. To me, it had everything I loved about Debian (a familiar /etc layout, a great packaging system, etc), but more of the useful (but non-free) packages and better forums for support. [K]ubuntu took something I loved, and made it easier for me to use.

Nexenta is a distribution of OpenSolaris based on Ubuntu. The idea is to make something much like Ubuntu, but with the fast, rock-solid Solaris kernel rather than Linux. Now, I believe the biggest problem with using OpenSolaris is the lack of a package manager on par with apt, not to mention all the other tools and programs I know and love. But with Nexenta, you get apt as well as over 12,000 packages. (Debian developers appear less than enthused. (I dare you to read more than 50% of that thread.))

I'm installing Nexenta on my laptop because I'm hoping this will be another case of taking something I love (Ubuntu) and making it better (with a more solid kernel, zfs, zones, dtrace, etc). I recognize that it might not be quite as good as Ubuntu in terms of the level of support for everything I use, but if it's most of the way there, the extra Solaris features might be worth it to me.



I wanted to run ZFS for most of my storage, and I definitely wanted the partitions (or slices, in Solaris-speak) encompassing /home and other non-system areas to be separate. That way, when I reinstall, I don't have to back that up - I can simply tell the installer to skip those partitions.


Not surprisingly (to me), the installation did not go terribly smoothly. Because of my storage goals (above), I couldn't use the default partitioning scheme. But the Nexenta installer does not have good support for manually partitioning your disk - either you let it decide how to arrange your partitions, your you use the cryptic format(1M) utility.

Note that format(1M) isn't usually too bad if you know what you're doing, but in my case, I was quickly turned off. When I selected my disk (c0d0), it asked me nearly a dozen questions whose answers I couldn't have known easily and I expected it to determine automatically. Apparently, this is not a common case, but I needed to know the number of heads on the disk, the number of sectors per track, the number of cylinders (data and alternate), the number of blocks per cylinder. There were a number of other questions, but those had a "default" option.

For the answers to these questions, I booted up my existing Ubuntu system and ran "fdisk -l". (Note: I didn't want to keep score, but at this point we have Linux: 1 and Solaris: 0.)

The other major problem I had was that once I did accomplish all this, when I rebooted, I got the word "GRUB" in the corner of my screen, and nothing else. The pretty GRUB menu never came up. I think this was related to a screwy partition table I had set up. More below, but after reinstalling with a "proper" setup, it seems to be working.

Slicing (Partitioning)

Important things to remember when setting up your slices (which I discovered from this multi-boot Solaris x86 page) is that slices 2, 8, and 9 are considered special:
  • Slice 2 should always be a partition with the "backup" tag which occupies the entire hard drive (I didn't even realize that slices could overlap).
  • Slice 8 should always be a partition with the "boot" tag
  • Slice 9 should always be a partition with the "alternate" tag and occupy 2 cylinders
I have yet to find any documentation on what the different tags mean, though.

Anyway, I expanded the example in the Nexenta Alpha 1 guide (which the Alpha 5 guide references if you need to manually partition the drive). I followed that guide closely, so I'm not going to repeat the steps here. But since my drive was already partitioned for Windows and Linux, I first had to delete all the existing partitions. In the format tool, I typed "partition" and then deleted each partition. Then I saved and exited the partition tool. Then I reentered it - it now got me to the default formatting described in that guide (a 100% Solaris disk).

Using their example as a guide, but taking into account my desire to use ZFS, I created the following table on my 100gb hard drive:

Slice #TagCylindersSizeComment
0root3-9167gbRoot partition
1swap917-10471gbSwap partition
2backup0-12157whole driveReserved - don't change this
3alternate1048-660242gbZFS 1
4alternate6603-1215742gbZFS 2
5unassigned0-00(Not used)
6unassigned0-00(Not used)
7unassigned0-00(Not used)
8boot0 - 08mbReserved - don't change this
9alternate1 - 216mbReserved - don't change this

Note that I split up my non-system storage space into two slices so that I can use zfs mirroring. I'd rather use multiple drives and raidz2 of course, but it's a laptop with just one drive. Having both mirrors on the same drive might be a performance hit (have to look into that), but should be more reliable. If the drive fails, I'm dead, but if there's a transient hardware error that only messes up some data, I can recover. I'll be regularly backing up this machine anyway (I hope).


With the exception of the problems noted above in the "Troubles" section, the installation went smoothly. On the second try (with a correct slice table), she booted up wonderfully. Time to go play!


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