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.

Host a VirtualBox VM on a FreeNAS iScsi target

Setup Freenas iScsi Target

Pre-requisites

1. A FreeNAS server with a ZFS filesystem. I have Freenas 8.04p2 with RAIDZ1 accross 3x2TB disks
2. Another computer on the same network with Virtual Box installed - in my case an ubuntu 11.04 workstation (sudo apt-get install virtualbox virtualbox-guest-additions virtualbox-guest-additions-iso)

Create ZFS Volume

Easy with freenas, just needs a name and a size. My case - 'coppervmroot' and 30gb.

Set up iScsi

1. Create a 'portal' - the default 0.0.0.0:3260 is fine.
2. Create an 'authorized initiator' using the defaults (all/all)
3. Create a target. name: coppervmroot, type 'disk', portal group '1', initiator group '1', auth method 'none.
4. Create a device extent. coppervmrootextent refering to the coppervmroot ZVOL
5. Create an 'associated target', in this case the coppervmrootextent and the coppervmroot target
6. Turn on iscsi !

Testing from Ubuntu

Get the iscsi tools:

sudo apt-get install open-iscsi open-iscsi-utils

 See what volumes are exported by (as root)

# iscsiadm -m discovery -t sendtargets -p 10.xx.xx.xx:3260
10.xx.xx.xx:3260,1 iqn.2002-02.jfdi.org.tgt:coppervmroot

Try mounting a the iScsi volume as a local block device

# iscsiadm -m node --targetname iqn.2002-02.jfdi.org.tgt:coppervmroot --portal 10.xx.xx.xx:3260 --login
Logging in to [iface: default, target: iqn.2002-02.jfdi.org.tgt:coppervmroot, portal: 10.xx.xx.xx,3260]
Login to [iface: default, target: iqn.2002-02.jfdi.org.tgt:coppervmroot, portal: 10.xx.xx.xx,3260]: successful

And you should see a device appear in /var/log/syslog:

# tail -f /var/log/syslog
Jun  5 ... sd 4:0:0:0: [sdc] Attached SCSI disk

OK, so unmount it:

# iscsiadm -m node --targetname iqn.2002-02.jfdi.org.tgt:coppervmroot --portal 10.xx.xx.xx:3260 --logout
Logging out of session [sid: 1, target: iqn.2002-02.jfdi.org.tgt:coppervmroot, portal: 10.xx.xx.xx,3260]
Logout of [sid: 1, target: iqn.2002-02.jfdi.org.tgt:coppervmroot, portal: 10.xx.xx.xx,3260]: successful

Setup Virtual Box VM with iScsi target for HDD

You can't (yet!) manage an iscsi volume from the Virtual Box GUI. But you can do it with the vboxmanage command:

vboxmanage storageattach copper --storagectl sata0 --port 1 --device 0 --type hdd --medium iscsi --server 10.xx.xx.xx --target iqn.2002-02.jfdi.org.tgt:coppervmroot 

That's it. Boot off a CD and install onto the iScsi HDD.

N.B. during installation my VM disconnected a couple of times. Resuming the VM (which stops automatically when this happens) seemed to do the trick.