by Alexandre Borges
Published June 2014
Part 1 - Using COMSTAR and ZFS to Configure a Virtualized Storage Environment
Part 2 - Playing with Swap Monitoring and Increasing Swap Space Using ZFS Volumes
Part 3 - Playing with ZFS Shadow Migration
Part 4 - Delegating a ZFS Dataset to a Non-Global Zone
Part 5 - Playing with ZFS Encryption
Part 6 - Playing with ZFS Snapshots
Imagine that we have some data on an older server running Oracle Solaris 11, and we need to migrate this data to a new server running Oracle Solaris 11.1. This is a classic case where we could use a new feature of Oracle Solaris 11 called Shadow Migration. Shadow Migration can also be used to migrate data from systems running Oracle Solaris 10 releases.
Using Shadow Migration is very easy; for example, we could migrate shared ZFS, UFS, or VxFS (Symantec) file systems through NFS or even through a local file system.
To simulate an example of using Shadow Migration to migrate data between two systems, we're going to use two virtual machines that have Oracle Solaris 11 installed (
solaris11-2) in a virtual environment provided by Oracle VM Virtual Box. Furthermore, in the
solaris11-2 host, we're going to share a file system (
/solaris11-2-pool/migrated-filesystem) and migrate the data inside this file system to the
The first step of this procedure is installing the
root@solaris11-1:~# pkg install shadow-migration Packages to install: 1 Create boot environment: No Create backup boot environment: No Services to change: 1 DOWNLOAD PKGS FILES XFER (MB) SPEED Completed 1/1 14/14 0.2/0.2 126k/s PHASE ITEMS Installing new actions 39/39 Updating package state database Done Updating image state Done Creating fast lookup database Done
As you can see, the shadows service is initially stopped:
root@solaris11-1:~# svcs -a | grep shadow disabled 18:22:13 svc:/system/filesystem/shadowd:default
So we must start it:
root@solaris11-1:~# svcadm enable svc:/system/filesystem/shadowd:default root@solaris11-1:~# svcs -a | grep shadow online 18:23:17 svc:/system/filesystem/shadowd:default
On the second machine (from where we want to shadow the file system), the file system must be shared using the NFS service and with the read-only attribute (
ro) to avoid changing its contents during the shadowing:
root@solaris11-2:~/SFHA601# share -F nfs -o ro /solaris11-2-pool/migrated-filesystem root@solaris11-2:~/SFHA601# share IPC$ smb - Remote IPC solaris11-2-pool_migrated-filesystem /solaris11-2-pool/migrated-filesystem nfs sec=sys,ro
The advantage of using Shadow Migration is that when the data migration begins, any NFS clients that are accessing the source file system automatically migrate to accessing the target file system.
On the first machine (
solaris11-1), we can confirm that
solaris11-2 is offering the file system through NFS by running the following command:
root@solaris11-1:/# dfshares solaris11-2 RESOURCE SERVER ACCESS TRANSPORT solaris11-2:/solaris11-2-pool/migrated-filesystem solaris11-2 - -
Now it's time to shadow the ZFS file system from the second machine (
solaris11-2) to the first one (
solaris11-1) by creating a file system named
root@solaris11-1:/rpool# zfs create -o shadow=nfs://solaris11-2/solaris11-2-pool/migrated-filesystem rpool/shadow_test
This can be a slow process. Afterwards, you should execute the
root@solaris11-1:/rpool# shadowstat EST BYTES BYTES ELAPSED DATASET XFRD LEFT ERRORS TIME rpool/shadow_test 4.73M - - 00:00:04 rpool/shadow_test 46.0M - - 00:00:14 rpool/shadow_test 52.7M - - 00:00:24 rpool/shadow_test 55.1M - - 00:00:34 rpool/shadow_test 57.5M - - 00:00:44 rpool/shadow_test 58.1M - - 00:00:54 rpool/shadow_test 59.6M 128M - 00:01:04 rpool/shadow_test 62.8M 224M - 00:01:14 rpool/shadow_test 89.0M 187M - 00:01:24 rpool/shadow_test 92.7M 360M - 00:01:34 rpool/shadow_test 120M 168M - 00:01:44 rpool/shadow_test 163M 8E - 00:01:54 rpool/shadow_test 178M 8E - 00:02:04 rpool/shadow_test 178M 8E - 00:02:14 rpool/shadow_test 178M 8E - 00:02:24 rpool/shadow_test 178M 8E - 00:02:34 No migrations in progress
We can verify that the migration finished by running the following command:
root@solaris11-1:/rpool# zfs get -r shadow rpool/shadow_test NAME PROPERTY VALUE SOURCE rpool/shadow_test shadow none -
Perfect! Everything worked as expected.
The same procedure could be done using two ZFS file systems. For example, we could create a new file system named
rpool/filesystem_source and copy a directory that contains many files into it:
root@solaris11-1:~# cp -r NetBackup_7.5_Solaris_x86/ /rpool/filesystem_source/ root@solaris11-1:~# zfs set readonly=on rpool/filesystem_source root@solaris11-1:~# zfs create -o shadow=file:///rpool/filesystem_source rpool/filesystem_target root@solaris11-1:~# shadowstat EST BYTES BYTES ELAPSED DATASET XFRD LEFT ERRORS TIME rpool/filesystem_target 107K - - 00:00:04 rpool/filesystem_target 51.2M - - 00:00:14 rpool/filesystem_target 114M - - 00:00:24 rpool/filesystem_target 114M - - 00:00:34 rpool/filesystem_target 114M - - 00:00:44 rpool/filesystem_target 114M - - 00:00:54 rpool/filesystem_target 114M 8E - 00:01:04 rpool/filesystem_target 114M 8E - 00:01:14 rpool/filesystem_target 114M 8E - 00:01:24 rpool/filesystem_target 672M 8E - 00:01:34 rpool/filesystem_target 672M 8E - 00:01:44 rpool/filesystem_target 672M 8E - 00:01:54 rpool/filesystem_target 672M 8E - 00:02:04 rpool/filesystem_target 672M 8E - 00:02:14 rpool/filesystem_target 672M 8E - 00:02:24 rpool/filesystem_target 672M 8E - 00:02:34 No migrations in progress
Wow!!! We repeated the recipe, but we used the appropriate syntax for shadowing between two local ZFS file systems. In the same way, we're able to confirm that the shadowing operation has finished.
Here are some links to other things I've written:
And here are some Oracle Solaris 11 resources:
Alexandre Borges is an Oracle ACE and who worked as an employee and contracted instructor at Sun Microsystems from 2001 to 2010 teaching Oracle Solaris, Oracle Solaris Cluster, Oracle Solaris security, Java EE, Sun hardware, and MySQL courses. Nowadays, he teaches classes for Symantec, Oracle partners, Hitachi, and EC-Council, and he teaches several very specialized classes about information security. In addition, he is a regular writer and columnist at Linux Magazine Brazil.
|Revision 1.0, 04/09/2014|