Can I add external log device after filesystem was created?

Can I add external log device after filesystem was created?

[Marcin Sura]

Hi,

I've created filesystem with default mkfs.xfs command, started to use
the filesystem. Few days later I've got nice SSD-based lun which can
be used as external log device.

Can I add that lun as external log device to an existing filesystem? How?

BR
Marcin

Re: Can I add external log device after filesystem was created?

[Eric Sandeen]

On 11/3/16 2:28 PM, Marcin Sura wrote:
> Hi,
> 
> I've created filesystem with default mkfs.xfs command, started to use
> the filesystem. Few days later I've got nice SSD-based lun which can
> be used as external log device.
> 
> Can I add that lun as external log device to an existing filesystem? How?
> 
> BR
> Marcin

There is no supported mechanism for doing this.  It can be done with xfs_db
disk-editing surgery, but that's not really recommended.

What is your reason for wanting to move the log?

-Eric

Re: Can I add external log device after filesystem was created?

[Marcin Sura]

Hi,

We are building huge test system with hundreds TB of data. We want to
execute some performance tests without and with external log device.
Filling in the data is a time consuming process, so my first idea was
to create the filesystem without external log, execute the tests and
then add external log and repeat the tests without recreating the
filesystem. Now I know I have to do this. Thanks

BR
Marcin

2016-11-03 20:57 GMT+01:00 Eric Sandeen <sandeen@sandeen.net>:
> On 11/3/16 2:28 PM, Marcin Sura wrote:
>> Hi,
>>
>> I've created filesystem with default mkfs.xfs command, started to use
>> the filesystem. Few days later I've got nice SSD-based lun which can
>> be used as external log device.
>>
>> Can I add that lun as external log device to an existing filesystem? How?
>>
>> BR
>> Marcin
>
> There is no supported mechanism for doing this.  It can be done with xfs_db
> disk-editing surgery, but that's not really recommended.
>
> What is your reason for wanting to move the log?
>
> -Eric

Re: Can I add external log device after filesystem was created?

[Eric Sandeen]

If it's just test data, I can give you a recipe for moving it with
xfs_db, I think - if you're willing to lose the filesystem if
something goes wrong.  ;)

-Eric

On 11/3/16 4:14 PM, Marcin Sura wrote:
> Hi,
> 
> We are building huge test system with hundreds TB of data. We want to
> execute some performance tests without and with external log device.
> Filling in the data is a time consuming process, so my first idea was
> to create the filesystem without external log, execute the tests and
> then add external log and repeat the tests without recreating the
> filesystem. Now I know I have to do this. Thanks
> 
> BR
> Marcin
> 
> 2016-11-03 20:57 GMT+01:00 Eric Sandeen <sandeen@sandeen.net>:
>> On 11/3/16 2:28 PM, Marcin Sura wrote:
>>> Hi,
>>>
>>> I've created filesystem with default mkfs.xfs command, started to use
>>> the filesystem. Few days later I've got nice SSD-based lun which can
>>> be used as external log device.
>>>
>>> Can I add that lun as external log device to an existing filesystem? How?
>>>
>>> BR
>>> Marcin
>>
>> There is no supported mechanism for doing this.  It can be done with xfs_db
>> disk-editing surgery, but that's not really recommended.
>>
>> What is your reason for wanting to move the log?
>>
>> -Eric
>