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Old 12-21-2010, 07:57 PM
Kevin C
 
Default Ext4 on CentOS 5.5 64bit

Yes, We use it for 4 months on our backup server, we no issue at the
moment. We have a lot of files, ext4 increase the backup speed. The
backup time is now 3hours, and was 5 hours with ext3.

Le 21/12/2010 21:22, Matt a crit :
> Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
> great deal of disk i/o and was wandering if ext4 would be better then
> ext3 for it?
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos

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Old 12-22-2010, 08:04 AM
Peter Kjellstrm
 
Default Ext4 on CentOS 5.5 64bit

On Tuesday, December 21, 2010 09:57:52 pm Kevin C wrote:
> Yes,

Well "works for you" may be more correct then. Hard to call it "stable"
especially in the context of an enterprise dist when it's officially a
"technology preview".

/Peter

> We use it for 4 months on our backup server, we no issue at the
> moment. We have a lot of files, ext4 increase the backup speed. The
> backup time is now 3hours, and was 5 hours with ext3.
>
> Le 21/12/2010 21:22, Matt a crit :
> > Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
> > great deal of disk i/o and was wandering if ext4 would be better then
> > ext3 for it?
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Old 12-22-2010, 11:19 AM
mcclnx mcc
 
Default Ext4 on CentOS 5.5 64bit

Anyone know ORACLE support ext4 file system or not?



--- 10/12/21 (二),Kevin C <linux@tuxalafenetre.net> 寫道:

> 寄件者: Kevin C <linux@tuxalafenetre.net>
> 主旨: Re: [CentOS] Ext4 on CentOS 5.5 64bit
> 收件者: "CentOS mailing list" <centos@centos.org>
> 日期: 2010年12月21日,二,下午3:57
> Yes, We use it for 4 months on our
> backup server, we no issue at the
> moment. We have a lot of files, ext4 increase the backup
> speed. The
> backup time is now 3hours, and was 5 hours with ext3.
>
> Le 21/12/2010 21:22, Matt a 嶰rit :
> > Is ext4 stable on CentOS 5.5 64bit?* I have an
> email server with a
> > great deal of disk i/o and was wandering if ext4 would
> be better then
> > ext3 for it?
> > _______________________________________________
> > CentOS mailing list
> > CentOS@centos.org
> > http://lists.centos.org/mailman/listinfo/centos
>
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>



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Old 12-23-2010, 06:12 AM
 
Default Ext4 on CentOS 5.5 64bit

Matt wrote:
> Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
> great deal of disk i/o and was wandering if ext4 would be better then
> ext3 for it?

Before committing to ext4 on a production server, it
would be good to consider the comments made in
https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45
which presumably still apply to current CentOS 5.5 64-bit kernels.
As I read it, Ts'o argues that the apparent loss of stability
compared to ext3 is a design issue in the realm of applications
that run atop it. I hope this is not a misreading.
--
Charles Polisher

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Old 12-23-2010, 06:35 AM
bedo
 
Default Ext4 on CentOS 5.5 64bit

ext4 better then ext3 !
you can install ext4 by yum
see:
https://ext4.wiki.kernel.org/index.php/Ext4_Howto#Compatibility



2010/12/23 <cpolish@surewest.net>


Matt wrote:

> Is ext4 stable on CentOS 5.5 64bit? *I have an email server with a

> great deal of disk i/o and was wandering if ext4 would be better then

> ext3 for it?



Before committing to ext4 on a production server, it

would be good to consider the comments made in

https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45

which presumably still apply to current CentOS 5.5 64-bit kernels.

As I read it, Ts'o argues that the apparent loss of stability

compared to ext3 is a design issue in the realm of applications

that run atop it. I hope this is not a misreading.

--

Charles Polisher



_______________________________________________

CentOS mailing list

CentOS@centos.org

http://lists.centos.org/mailman/listinfo/centos



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Old 12-23-2010, 02:08 PM
Ross Walker
 
Default Ext4 on CentOS 5.5 64bit

On Dec 23, 2010, at 2:12 AM, cpolish@surewest.net wrote:

> Matt wrote:
>> Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
>> great deal of disk i/o and was wandering if ext4 would be better then
>> ext3 for it?
>
> Before committing to ext4 on a production server, it
> would be good to consider the comments made in
> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45
> which presumably still apply to current CentOS 5.5 64-bit kernels.
> As I read it, Ts'o argues that the apparent loss of stability
> compared to ext3 is a design issue in the realm of applications
> that run atop it. I hope this is not a misreading.

Waiting for applications to be properly written, ie use fsync(), is no way to pick a file system. You'd have the same problems on xfs or any other file system that does delayed writes.

It was only a side-effect of ext3's journal=ordered that caused it to flush dirty pages every 5 seconds. If that's what you want then you can use sysctl to tune vm to flush every 5 seconds and that will cover all delayed write file systems.

-Ross

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Old 12-23-2010, 03:02 PM
Les Mikesell
 
Default Ext4 on CentOS 5.5 64bit

On 12/23/2010 9:08 AM, Ross Walker wrote:
> On Dec 23, 2010, at 2:12 AM, cpolish@surewest.net wrote:
>
>> Matt wrote:
>>> Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
>>> great deal of disk i/o and was wandering if ext4 would be better then
>>> ext3 for it?
>>
>> Before committing to ext4 on a production server, it
>> would be good to consider the comments made in
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45
>> which presumably still apply to current CentOS 5.5 64-bit kernels.
>> As I read it, Ts'o argues that the apparent loss of stability
>> compared to ext3 is a design issue in the realm of applications
>> that run atop it. I hope this is not a misreading.
>
> Waiting for applications to be properly written, ie use fsync(), is no way to pick a file system. You'd have the same problems on xfs or any other file system that does delayed writes.

But note that the reason applications don't use fsync() when they should
is probably due to linux historically not implementing it in a
reasonable way (i.e. it would flush the entire filesystem buffer and
wait for completion instead of just the requested file's outstanding
blocks). Not sure when/if that was fixed - but it is also probably
behind the old impressions that mysql is faster than postgresql.

--
Les Mikesell
lesmikesell@gmail.com
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Old 12-23-2010, 03:21 PM
Christopher Chan
 
Default Ext4 on CentOS 5.5 64bit

On Thursday, December 23, 2010 11:08 PM, Ross Walker wrote:
> On Dec 23, 2010, at 2:12 AM, cpolish@surewest.net wrote:
>
>> Matt wrote:
>>> Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
>>> great deal of disk i/o and was wandering if ext4 would be better then
>>> ext3 for it?
>>
>> Before committing to ext4 on a production server, it
>> would be good to consider the comments made in
>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45
>> which presumably still apply to current CentOS 5.5 64-bit kernels.
>> As I read it, Ts'o argues that the apparent loss of stability
>> compared to ext3 is a design issue in the realm of applications
>> that run atop it. I hope this is not a misreading.
>
> Waiting for applications to be properly written, ie use fsync(), is no way to pick a file system. You'd have the same problems on xfs or any other file system that does delayed writes.

Whoa, whoa. 1) Theodore was not pushing fsync, he was pushing fsyncdata
and switching from storing configuration in thousands of small files to
everything in one sqlite database or similar single file solution 2) you
bet applications that are data sensitive better be properly written and
making proper and efficient use of system calls such as fsync, fsyncdata
and whatever else there is and 3) write barriers were introduced to
ensure that fsync/fsyncdata do not lie unlike the previous behaviour
where they return before data is safely written to media. In the case of
email, you bet the entire toolchain better do fsync. postmark from
Netapp as a benchmark for mail delivery was completely laughable because
it does not use a single fsync call whereas all mta credible software
(sendmail, postfix, qmail, exim) use fsync/fsyncdata where needed.
Unless you want thousands of zero'd files in say the mail queue, you
better make sure that both the app and the filesystem do what they are
supposed to do. Which is use fsync/fsyncdata and filesystem must support
write barriers if disk write caches are to be left on or disable disk
write caches and take big performance hit.

If a filesystem does not support write barriers (like JFS) you bet it is
a concern to take note of with regard to your hardware (eg: do you have
hardware raid with sufficient BBU cache?). Then there is the case of
running on top of LVM which I suspect does not have write barrier
support backported to RHEL/Centos 5.5.


>
> It was only a side-effect of ext3's journal=ordered that caused it to flush dirty pages every 5 seconds. If that's what you want then you can use sysctl to tune vm to flush every 5 seconds and that will cover all delayed write file systems.
>

More precisely, the journal is committed every 5 seconds no matter what
the mode.

I'd stick with ext3 + data=journal with the journal either on some uber
fast and large external BBU nvram block device (you can get up to 1TB
with speeds of 750MiB/sec+ if you have a fat enough bus) or on hardware
raid with sufficient BBU cache for an email server. Or anything with
barrier support through the entire chain (read: no LVM).

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Old 12-23-2010, 03:28 PM
Christopher Chan
 
Default Ext4 on CentOS 5.5 64bit

On Friday, December 24, 2010 12:02 AM, Les Mikesell wrote:
> On 12/23/2010 9:08 AM, Ross Walker wrote:
>> On Dec 23, 2010, at 2:12 AM, cpolish@surewest.net wrote:
>>
>>> Matt wrote:
>>>> Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
>>>> great deal of disk i/o and was wandering if ext4 would be better then
>>>> ext3 for it?
>>>
>>> Before committing to ext4 on a production server, it
>>> would be good to consider the comments made in
>>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45
>>> which presumably still apply to current CentOS 5.5 64-bit kernels.
>>> As I read it, Ts'o argues that the apparent loss of stability
>>> compared to ext3 is a design issue in the realm of applications
>>> that run atop it. I hope this is not a misreading.
>>
>> Waiting for applications to be properly written, ie use fsync(), is no way to pick a file system. You'd have the same problems on xfs or any other file system that does delayed writes.
>
> But note that the reason applications don't use fsync() when they should
> is probably due to linux historically not implementing it in a
> reasonable way (i.e. it would flush the entire filesystem buffer and
> wait for completion instead of just the requested file's outstanding
> blocks). Not sure when/if that was fixed - but it is also probably
> behind the old impressions that mysql is faster than postgresql.
>

Can we drop the fsync nonsense? Apps that are data sensitive should be
using fsync/fsyncdata (fsync is a posix specification so the history of
how linux implemented fsync has nothing to do with whether applications
used it or not) otherwise it should not be even consider for the task.
The lying fsync/fsyncdata was fixed when write barrier support was
introduced and filesystems updated to use write barriers. As for the
flush entire buffer...IIRC, that is specific to ext3 and even that
should be now gone with the update to write barrier support.
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Old 12-23-2010, 04:03 PM
Les Mikesell
 
Default Ext4 on CentOS 5.5 64bit

On 12/23/2010 10:28 AM, Christopher Chan wrote:
>
>>>> Matt wrote:
>>>>> Is ext4 stable on CentOS 5.5 64bit? I have an email server with a
>>>>> great deal of disk i/o and was wandering if ext4 would be better then
>>>>> ext3 for it?
>>>>
>>>> Before committing to ext4 on a production server, it
>>>> would be good to consider the comments made in
>>>> https://bugs.launchpad.net/ubuntu/+source/linux/+bug/317781/comments/45
>>>> which presumably still apply to current CentOS 5.5 64-bit kernels.
>>>> As I read it, Ts'o argues that the apparent loss of stability
>>>> compared to ext3 is a design issue in the realm of applications
>>>> that run atop it. I hope this is not a misreading.
>>>
>>> Waiting for applications to be properly written, ie use fsync(), is no way to pick a file system. You'd have the same problems on xfs or any other file system that does delayed writes.
>>
>> But note that the reason applications don't use fsync() when they should
>> is probably due to linux historically not implementing it in a
>> reasonable way (i.e. it would flush the entire filesystem buffer and
>> wait for completion instead of just the requested file's outstanding
>> blocks). Not sure when/if that was fixed - but it is also probably
>> behind the old impressions that mysql is faster than postgresql.
>>
>
> Can we drop the fsync nonsense?

No, if you don't remember history you are doomed to repeat it.

> Apps that are data sensitive should be
> using fsync/fsyncdata (fsync is a posix specification so the history of
> how linux implemented fsync has nothing to do with whether applications
> used it or not) otherwise it should not be even consider for the task.
> The lying fsync/fsyncdata was fixed when write barrier support was
> introduced and filesystems updated to use write barriers. As for the
> flush entire buffer...IIRC, that is specific to ext3 and even that
> should be now gone with the update to write barrier support.

It's one of those 'have you stopped beating your wife things'. Apps
that correctly used fsync were slow because of the OS implementation, so
people used other apps. So now you have popular apps that do things
wrong.

--
Les Mikesell
lesmikesell@gmail.com
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