Re: Is ext4 safe for a production server?

[Ross Walker <rswwalker@xxxxxxxxx>]

On Dec 10, 2009, at 7:52 PM, Mark Caudill <markca@xxxxxxxxxxxx> wrote:

> Christopher Chan wrote:
>> Morten Torstensen wrote:
>>> On 08.12.2009 13:34, Chan Chung Hang Christopher wrote:
>>>>> Speaking for me (on Linux systems) on top of LVM on top of md.  
>>>>> On IRIX
>>>>> as it was intended.
>>>>>
>>>> That is a disaster combination for XFS even now. You mentioned some
>>>> pretty hefty hardware in your other post...
>>> If XFS doesn't play well with LVM, how can it even be an option? I
>>> couldn't live without LVM...
>>>
>>
>> I meant it in the sense of data guarantee. XFS has a major history of
>> losing data unless used with hardware raid cards that have a bbu  
>> cache.
>> That changed when XFS got barrier support.
>>
>> However, anything on LVM be it ext3, ext4 or XFS that has barrier
>> support will not be able to use barriers because device-mapper does  
>> not
>> support barriers and therefore, if you use LVM, it better be on a
>> hardware raid array where the card has bbu cache.
>
> Wait, just to be clear, are you saying that all use of LVM is a bad  
> idea
> unless on hardware RAID? That's bad it if it's true since it seems  
> to me
> that most modern distros like to use LVM by default. Am I missing  
> something?

If you use a leading edge distro then they will most likely be using a  
LVM version with barrier support as it was implemented as of  
2.6.29-2.6.30+.

It should be backported by the next release of CentOS hopefully.

-Ross
  
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