[ale] Extend file system with -r while using lvextend command

[Elliot Holden]

Ok, thank you all for the responses. Makes sense.


E.



Elliot Holden
706-231-9776
elliot at elliotmywebguy.com
http://www.elliotmywebguy.com

On 5/8/17 10:44 AM, Kyle Brieden wrote:
> Hey Elliot,
>
> I've been doing it this way for years.  I know for srure that it is 
> safe to extend an ext# FS online.  I believe XFS is safe to extend 
> online, as well.  The lvextend -r flag just calls "resize2fs" (or 
> tune2fs?  I honestly can't recall which it is off hand right now...) 
> for you.  For what it's worth, I've extended filesystems while they 
> were being written to this way to avoid having a filesystem fill up in 
> the middle of a long-running process and breaking the process.
>
> Sizing a filesystem down, on the other hand, should never be done 
> online.  But extending a filesystem online is typically safe.
>
> I also recently discovered the hard way that either XFS or ZFS (I 
> can't recall which, as I use both but very, VERY little) can be 
> extended, but not shrunk.  As it, the spec for the FS was actively 
> written to not allow shrinking.  Struck me as odd, but I guess there's 
> a logical reason there.
>
> ---
> Very respectfully,
> Kyle Brieden
>
> On 08-05-2017 10:31, Elliot Holden wrote:
>> I found out you can extend the filesystem while extending the lvm
>> simultaneously. So it does not have to be in 2 separate commands.
>> Using the -r option or --resizefs with lvextend will do the trick.
>> This way you don't have to unmount the filesystem, extend the
>> filesystem (with xfs_growfs) and then remount the filesystem. Here is
>> the syntax.
>>
>> [elliot at newton ~]$ sudo lvextend -l +100%FREE -r /dev/rhel/home
>>
>>
>> Does any see an issue with doing this type of modification while the
>> filesystem is still mounted? Does anyone know if the filesystem gets
>> unmounted and remounted during this command while using -r ? Just in
>> case some other process is writing to the filesystem at the same time.
>> It's been brought to my attention by a member of my Perl group that
>> you could potentially lose data this way. So I wanted to find out if
>> there are any protections going on in the background while executing
>> this command.
>>
>>
>> Thanks
>>
>>
>> E.
>
>
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