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Old 12-13-2009, 02:15 PM
Pasi Kärkkäinen
 
Default Is ext4 safe for a production server?

On Fri, Dec 11, 2009 at 09:20:24AM +0800, Christopher Chan wrote:
> Mark Caudill 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?
> >
>
> Yes, the Linux kernel has long been criticized for a fake
> fsync/fsyncdata implementation. At the latest, since 2001. Unless you
> had your hard drive caches turned off, you were at risk of losing data
> no matter what you used: ext2, ext3, reiserfs, xfs, jfs, whether on lvm
> or not.
>
> Write barriers were introduced to give data guarantees with hard drives
> that have their write cache enabled. Unfortunately, not everything has
> been given barrier support. LVM and JFS do not have write barrier support.
>

https://www.redhat.com/archives/dm-devel/2009-December/msg00079.html

"Barriers are now supported by all the types of dm devices."

-- Pasi

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Old 12-13-2009, 02:37 PM
Chan Chung Hang Christopher
 
Default Is ext4 safe for a production server?

>> Write barriers were introduced to give data guarantees with hard drives
>> that have their write cache enabled. Unfortunately, not everything has
>> been given barrier support. LVM and JFS do not have write barrier support.
>>
>>
>
> https://www.redhat.com/archives/dm-devel/2009-December/msg00079.html
>
> "Barriers are now supported by all the types of dm devices."
>
>

Wunderbar!

Now if the IBM team will add barrier support to JFS...
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Old 12-13-2009, 09:08 PM
Ross Walker
 
Default Is ext4 safe for a production server?

On Dec 13, 2009, at 10:15 AM, Pasi Kärkkäinen <pasik@iki.fi> wrote:

> On Fri, Dec 11, 2009 at 09:20:24AM +0800, Christopher Chan wrote:
>> Mark Caudill 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?
>>>
>>
>> Yes, the Linux kernel has long been criticized for a fake
>> fsync/fsyncdata implementation. At the latest, since 2001. Unless you
>> had your hard drive caches turned off, you were at risk of losing
>> data
>> no matter what you used: ext2, ext3, reiserfs, xfs, jfs, whether on
>> lvm
>> or not.
>>
>> Write barriers were introduced to give data guarantees with hard
>> drives
>> that have their write cache enabled. Unfortunately, not everything
>> has
>> been given barrier support. LVM and JFS do not have write barrier
>> support.
>>
>
> https://www.redhat.com/archives/dm-devel/2009-December/msg00079.html
>
> "Barriers are now supported by all the types of dm devices."

I wonder how long till it's backported to RHEL?

-Ross

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Old 12-14-2009, 07:08 AM
Jussi Hirvi
 
Default Is ext4 safe for a production server?

>> On Fri, Dec 11, 2009 at 9:52 AM, Jussi Hirvi <listmember@greenspot.fi> wrote:
>> P.S. Do you really have to quote the whole thread when you respond?
>
On 11.12.2009 20:28, Ross Walker wrote:
> No just the relevant parts.

:-D

My point exactly. What I meant to say was "oh please, don't quote
everything all the time".

- Jussi

--
Jussi Hirvi * Green Spot
Topeliuksenkatu 15 C * 00250 Helsinki * Finland
Tel. +358 9 493 981 * Mobile +358 40 771 2098 (only sms)
jussi.hirvi@greenspot.fi * http://www.greenspot.fi
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Old 12-16-2009, 01:47 AM
Mike Fedyk
 
Default Is ext4 safe for a production server?

On Thu, Dec 10, 2009 at 12:06 PM, Morten Torstensen <morten@mortent.org> wrote:
> On 05.12.2009 18:15, Miguel Medalha wrote:
>>> And, as of CentOS 5.4, xfs is now enabled in the kernel, so
>>> no need for any external kernel module. But yes, this is available for
>>> x86_64 only
>>
>> ... a decision that many people have trouble at understanding!
>
> XFS is not stable on 32-bit systems. You should not use it there. You
> need a 64-bit kernel.
>
> Default for servers should be 64-bit now anyway. Not many reasons left
> for a 32-bit system, and more and more 3. party applications have less
> and less support for 32-bit platforms in general.

Unless you're talking about desktop systems and things like flash...
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Old 12-16-2009, 06:21 AM
Mathieu Baudier
 
Default Is ext4 safe for a production server?

>> and less support for 32-bit platforms in general.
>
> Unless you're talking about desktop systems and things like flash...

(OT) The beta Flash plugin for 64 bits works really well, I use it for
months on Fedora and CentOS:
http://labs.adobe.com/downloads/flashplayer10_64bit.html
cd /usr/lib64/mozilla/plugins
sudo tar -xzf ~/Downloads/libflashplayer-10.0.32.18.linux-x86_64.so.tar.gz
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