Ubuntu NAS - ZFS on the HP Microserver

HP Microserver N40L

I had loads of fun setting up FreeNAS on a HP Microserver and can highly recommend this combination for a small home/office file server. But I had a few problems mainly with the performance and stability of the iScsi driver that comes with it. So I decided to pull out the FreeNAS/freebsd root disk and put in a new one on which to check out Ubuntu 12.04 server in combination with the native linux ZFS filesystem.

My target was to get 1Gb/s read and write performance out of the little microserver - ideally iScsi, but NFS would be OK too. Amazingly although the former appears to be a little optimistic the latter is acheivable.

I had setup FreeNAS with 3x2TB disks in a RAIDZ1 array. I replaced the root disk with a new one leaving the 3 ZFS disks in situ and installed ubuntu 12.04 server on the fresh root disk. I created a 'nas' user account for the box and got the installer to put SSH on for me, but nothing else.

ZFS installation is straightforward - i installed bonnie++ too so I could do some benchmarks on the box.

# apt-get update 

# apt-get upgrade 

# apt-get install python-software-properties 

# apt-add-repository ppa:zfs-native/stable 

# apt-get update 

# apt-get install ubuntu-zfs nfs-server sysstat iscsitarget iscsitarget-dkms open-iscsi bonnie

Once installed mounting the existing ZFS array was a case of doing

 # zfs import -f nasvol

and /nasvol appeared by magic on the root of the filesystem.

I then set about benchmarking performance of ZFS, ext4 (the root filesystem) NFS, iScsi using bonnie++. The fastest combination turned out to be a 4 drive RAID10 ZFS setup with NFS. I couldn't get iScsi to perform without large latency, i/o coming in bursts or high CPU. NFS on the other hand was pretty sweet - locally managing 180MB/s write and 250MB/s read. NFS speeds top out at 96MB/s write and 105MB/s read.

To get this performance, a few tips:

1. ZFS performance is woeful (40MB/s) unless you create the zpool with '-o ashift=12'. This makes it use 4k blocks (i think) which coincides with the modern SATA drives.
2. More spindles, more speed. Raid 10 gives it 4 to read from and 2 to spread the writes accross. 
3. RAIDZ1 is great, but not with the Microserver's horsepower. Get an i5/i7 and you'll be able to enjoy deduplication too!
4. NFS server set up rw, async, no_subtree_check, wdelay. (The UPS is on order)
5. NFS client set up to use rsize/wsize 65536, tcp, and noatime.
6. It's possible to disable checksumming in ZFS, but it didn't make much different in this setup.

As I mentioned above, iScsi performance didn't really compare too well with NFS. My ZFS zVol iScsi target managed 70MB/s writes and 50MB/s reads. None of the combinations of LVM2/ext4/iScsi I tried managed more than 80MB/s write although some did manage 100MB/s read.

Stop Ubuntu 12.04 NetworkManager meddling!

Annoying Notifications!

After adding a couple of extra NICs to my work Ubuntu 12.04 desktop PC - part of an ongoing work with our office NAS/iScsi server - the network icon was blinking away trying to do something useful with the new cards.  Mildly annoying when in the office. Horrid when accessing remotely as the notifications eat lots of bandwidth. At the same time it was generating a fair amount of guff in /var/log/syslog.

Easy, I thought - i'll go fix them in /etc/network/interfaces... ...hang on:

auto lo
iface lo inet loopback

where's eth0 gone?! It seems that by default all is now managed by the network manager - just what I want most of the time especially on my notebook. But not what I want right now. Should I disable it?

root@welbeck:/run# service network-manager stop
network-manager stop/waiting
root@welbeck:/run# ifconfig
lo        Link encap:Local Loopback
          inet addr:127.0.0.1  Mask:255.0.0.0
          inet6 addr: ::1/128 Scope:Host
          UP LOOPBACK RUNNING  MTU:16436  Metric:1
          RX packets:118 errors:0 dropped:0 overruns:0 frame:0
          TX packets:118 errors:0 dropped:0 overruns:0 carrier:0
          collisions:0 txqueuelen:0
          RX bytes:8230 (8.2 KB)  TX bytes:8230 (8.2 KB)

Eth0 has gone! Not quite what I had in mind. A quick dig into the manpage for NetworkManager.conf (in /etc/NetworkManager) though has this:

      managed=false | true
              Controls whether interfaces listed in the 'interfaces' file  are
              managed  by  NetworkManager.   If  set  to true, then interfaces
              listed in /etc/network/interfaces are managed by NetworkManager.
              If  set  to  false,  then  any  interface  listed  in  /etc/net‐
              work/interfaces will be ignored by NetworkManager. Remember that
              NetworkManager controls the default route, so because the inter‐
              face is ignored, NetworkManager may assign the default route  to
              some  other  interface.  When the option is missing, false value
              is taken as default.

Sounds like it does Just the right thing(TM) then. So quick hack of /etc/network/interfaces

auto loiface lo inet loopback
auto eth0iface eth0 inet dhcp
auto eth1iface eth1 inet manual
auto eth2iface eth2 inet manual

And a service network-manager stop/start... 

And it's wound it's neck in.