[CentOS] LVM + XFS + external log + snapshots

Sat Jun 22 23:52:36 UTC 2013
aurfalien <aurfalien at gmail.com>

On Jun 21, 2013, at 2:58 PM, Joseph L. Casale wrote:

>> So I have an XFS file system within LVM  which has an external log.
>> A snapshot volume is created w/o issue;
>> But when i try to mount the file system;
>> mount: /dev/mapper/vg_spock_data-datasnapshot already mounted or /snapshot busy
> So the filesystem was built requiring an external log device?
> Let me guess, the original block device is still mounted and accessing its log device?

Based on some superb feed back from the XFS list, I have decided to place the log on an LVM rather then raw device that its on now and then freeze both and run the snapshot.

I'll first move the log to a diff device and convert sdc1 to LVM, move the log back and then snap away.

Word is that as of Centos 6.2, there is no need to use an external log due to this thing called delaylog.

However my env this server is being used for is very metadata intense, more so then normal.

Hence I do feel an external mirrored SSD log is the way to go.

- aurf