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-   -   Is ext4 safe for a production server? (http://www.linux-archive.org/centos/291026-ext4-safe-production-server.html)

Jure Pečar 12-05-2009 07:37 PM

Is ext4 safe for a production server?
 
On Sat, 05 Dec 2009 10:48:56 -0800
John R Pierce <pierce@hogranch.com> wrote:

> Timo Schoeler wrote:
> > For enterprise environments my favorite FS is XFS, YMMV, though.
> >
>
> I've always avoided XFS because A) it wsan't supported natively in RHEL
> anyways, and B) I've heard far too many stories about catastrophic loss
> problems and day long FSCK sessions after power failures [1] or what
> have you
>
> is B) no longer an issue?

You get horror stories about anything, depending on which people you ask.
For example, where reiserfs was supposed to eat data left and right some
years ago, I had 6 data losing crashes on ext3 and 0 with reiserfs. On same
machine, same disks, so same conditions. Go figure.

> I wanna know how come JFS/JFS2 (originally from IBM) isn't more popular
> in the linux world? At least as implemented in AIX, its rock stable,
> journaling, excellent performance, and handles both huge files and lots
> of tiny files without blinking. jfs2 handles really huge file systems,
> too. I really like how, in AIX, the VM and FS tools are coordinated, so
> expanding and reorganizing file systems is trivial, nearly as simple as
> Sun's ZFS.

AFAIK AIX JFS != Linux JFS. It's more like OS/2 JFS and IBM
ported it to linux to enable their os/2 customers to move to linux.

Also whenever fs reliability discussion pops up I like to point people to
this paper: http://www.cs.wisc.edu/wind/Publications/iron-sosp05.pdf
Tables on page 8 are most amusing.
Also shows which filesystems were developed in an academic world and which
were engineered in a real world ;)


--

Jure Pečar
http://jure.pecar.org
http://f5j.eu
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John R Pierce 12-05-2009 08:04 PM

Is ext4 safe for a production server?
 
Jure Pečar wrote:
> AFAIK AIX JFS != Linux JFS. It's more like OS/2 JFS and IBM
> ported it to linux to enable their os/2 customers to move to linux.
>

that same OS/2 JFS was backported to AIX as JFS2, I believe.


> Also whenever fs reliability discussion pops up I like to point people to
> this paper: http://www.cs.wisc.edu/wind/Publications/iron-sosp05.pdf
>

interesting, but that article is 5 years old. I'd be surprised if most
of the implementation 'bugs' and anomalies discussed have not since been
addressed.

I do wish more file systems and volume managers implemented block
checksumming, which provides end to end integrity both for data and
metadata. Afaik, only Sun's ZFS fully implements this approach.



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Chan Chung Hang Christopher 12-05-2009 10:48 PM

Is ext4 safe for a production server?
 
Jure Pečar wrote:
> On Sat, 05 Dec 2009 10:48:56 -0800
> John R Pierce <pierce@hogranch.com> wrote:
>
>
>> Timo Schoeler wrote:
>>
>>> For enterprise environments my favorite FS is XFS, YMMV, though.
>>>
>>>
>> I've always avoided XFS because A) it wsan't supported natively in RHEL
>> anyways, and B) I've heard far too many stories about catastrophic loss
>> problems and day long FSCK sessions after power failures [1] or what
>> have you
>>
>> is B) no longer an issue?
>>
>
> You get horror stories about anything, depending on which people you ask.
> For example, where reiserfs was supposed to eat data left and right some
> years ago, I had 6 data losing crashes on ext3 and 0 with reiserfs. On same
> machine, same disks, so same conditions. Go figure.
>
>
Prior to 2.4.18 reiserfs was not in sync with the then ever changing vfs
layer hence the data losses. It became stable after 2.4.18.

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Chan Chung Hang Christopher 12-05-2009 10:52 PM

Is ext4 safe for a production server?
 
John R Pierce wrote:
> Timo Schoeler wrote:
>
>> For enterprise environments my favorite FS is XFS, YMMV, though.
>>
>>
>
> I've always avoided XFS because A) it wsan't supported natively in RHEL
> anyways, and B) I've heard far too many stories about catastrophic loss
> problems and day long FSCK sessions after power failures [1] or what
> have you
>

Fixed with the introduction of barriers for stuff that use fsync
(therefore xfs on a partition, not lvm since dm does not support
barriers) but then one probably uses hw raid with big bbu caches for xfs....

> is B) no longer an issue?
>
> I wanna know how come JFS/JFS2 (originally from IBM) isn't more popular
> in the linux world? At least as implemented in AIX, its rock stable,
> journaling, excellent performance, and handles both huge files and lots
> of tiny files without blinking. jfs2 handles really huge file systems,
> too. I really like how, in AIX, the VM and FS tools are coordinated, so
> expanding and reorganizing file systems is trivial, nearly as simple as
> Sun's ZFS.
>
yeah, love jfs. Using that in Ubuntu land.
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Les Mikesell 12-05-2009 11:43 PM

Is ext4 safe for a production server?
 
Chan Chung Hang Christopher wrote:
> John R Pierce wrote:
>> Timo Schoeler wrote:
>>
>>> For enterprise environments my favorite FS is XFS, YMMV, though.
>>>
>>>
>> I've always avoided XFS because A) it wsan't supported natively in RHEL
>> anyways, and B) I've heard far too many stories about catastrophic loss
>> problems and day long FSCK sessions after power failures [1] or what
>> have you
>>
>
> Fixed with the introduction of barriers for stuff that use fsync
> (therefore xfs on a partition, not lvm since dm does not support
> barriers) but then one probably uses hw raid with big bbu caches for xfs....
>
>> is B) no longer an issue?
>>
>> I wanna know how come JFS/JFS2 (originally from IBM) isn't more popular
>> in the linux world? At least as implemented in AIX, its rock stable,
>> journaling, excellent performance, and handles both huge files and lots
>> of tiny files without blinking. jfs2 handles really huge file systems,
>> too. I really like how, in AIX, the VM and FS tools are coordinated, so
>> expanding and reorganizing file systems is trivial, nearly as simple as
>> Sun's ZFS.
>>
> yeah, love jfs. Using that in Ubuntu land.

Do any of these handle per-file fsync() in a reasonable way (i.e. not waiting to
flush the entire filesystem buffer)?

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Brian Mathis 12-06-2009 02:47 AM

Is ext4 safe for a production server?
 
On Sat, Dec 5, 2009 at 10:20 AM, Miguel Medalha <miguelmedalha@sapo.pt> wrote:
> I am about to install a new server running CentOS 5.4. The server will
> contain pretty critical data that we can't afford to corrupt.
>
> I would like to benefit from the extra speed and features of a ext4
> filesystem but I don't have any experience with it.
> Is there some member of the list who can enlighten me on whether ext4 is
> mature enough to be used on a production server without too much risk?
>
> Thank you!
>

Regardless of the technical issues offered here, ask yourself this: Do
you really want to be experimenting with a new file system on a
production server with "pretty critical data"? Since you asked about
"too much risk", I think you already answered the question.

Any sane process would involve installing it on a low priority test
server, running for a while to see how it goes, and learning about new
features or tools. After you've done that on a few lower priority
servers, for maybe a year or so, then you might start to _think_ about
using it on a production server like this.

My guess is that any additional speed can come from tuning other areas
of your server and disk subsystem. What hardware do you have? What
kind of disks? Using RAID? What level? Have you looked into
aligning your partitions with the RAID blocks? I'm sure that some of
the hardcore disk I/O people on the list can ask better questions and
give more meaningful recommendations.
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Ian Forde 12-06-2009 09:43 AM

Is ext4 safe for a production server?
 
On Sat, 2009-12-05 at 22:47 -0500, Brian Mathis wrote:
> On Sat, Dec 5, 2009 at 10:20 AM, Miguel Medalha <miguelmedalha@sapo.pt> wrote:
> > I am about to install a new server running CentOS 5.4. The server will
> > contain pretty critical data that we can't afford to corrupt.
> >
> > I would like to benefit from the extra speed and features of a ext4
> > filesystem but I don't have any experience with it.
> > Is there some member of the list who can enlighten me on whether ext4 is
> > mature enough to be used on a production server without too much risk?
> >
> > Thank you!
> >
>
> Regardless of the technical issues offered here, ask yourself this: Do
> you really want to be experimenting with a new file system on a
> production server with "pretty critical data"? Since you asked about
> "too much risk", I think you already answered the question.
>
> Any sane process would involve installing it on a low priority test
> server, running for a while to see how it goes, and learning about new
> features or tools. After you've done that on a few lower priority
> servers, for maybe a year or so, then you might start to _think_ about
> using it on a production server like this.
>
> My guess is that any additional speed can come from tuning other areas
> of your server and disk subsystem. What hardware do you have? What
> kind of disks? Using RAID? What level? Have you looked into
> aligning your partitions with the RAID blocks? I'm sure that some of
> the hardcore disk I/O people on the list can ask better questions and
> give more meaningful recommendations.

Funny that - that's the kind of answer I was hoping to see on this list.
The key issue was the fact that it's a production server. As a data
point, I've been using mythtv at home for about 6 years. (Has it really
been that long? Wow!) During that time, I've been using XFS filesystems
for media storage for about the last 4 or 5. I haven't had a problem
with it yet, though that doesn't preclude the possibility of it
occurring at some later date.

(Even, now that I've written this, it may fail several seconds from now,
given that I may have jinxed it!)

Anyhoo - due to this experience with it for my data at home which is
constantly been written and rewritten - (mythtv is pretty intensive on
systems - run it for a few years and BELIEVE ME - you'll find out where
the weak points in various OS components are...) I've found XFS safe
enough to use at work on production database servers.

It works for me. It may not for you, but I'm happy so far.

Again - this may all change tomorrow, but YMMV, as there's no such thing
as software liability, and open source may eat your cat, make your dog
toss its cookies on your lap, and cause the universe to unspool itself
in your Wheaties tomorrow. We all take our chances, and it's a matter
of how much risk we're willing to shoulder. As I said, I went through
my process and deemed it acceptable...

-I

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"Brent L. Bates" 12-07-2009 02:38 PM

Is ext4 safe for a production server?
 
XFS is the most stable file system I've seen or used. I've seen it
survive power failures and disk problems with out a problem. It is the ONLY
file system I trust. It is stable, reliable, dependable, and practically
bullet proof. I've been using XFS almost since it came into existence on
SGI's (IRIX) and we've been using it under Linux for years too, also with out
problems.
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cornel panceac 12-07-2009 02:55 PM

Is ext4 safe for a production server?
 
2009/12/7 Brent L. Bates <blbates@vigyan.com>

* * XFS is the most stable file system I've seen or used. *I've seen it

survive power failures and disk problems with out a problem. *It is the ONLY

file system I trust. *It is stable, reliable, dependable, and practically

bullet proof. *I've been using XFS almost since it came into existence on

SGI's (IRIX) and we've been using it under Linux for years too, also with out

problems.



what other file systems you've used and how they compare to ext4? thnx

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Les Mikesell 12-07-2009 03:26 PM

Is ext4 safe for a production server?
 
Brent L. Bates wrote:
> XFS is the most stable file system I've seen or used. I've seen it
> survive power failures and disk problems with out a problem. It is the ONLY
> file system I trust. It is stable, reliable, dependable, and practically
> bullet proof. I've been using XFS almost since it came into existence on
> SGI's (IRIX) and we've been using it under Linux for years too, also with out
> problems.

I think the main source of reported problems was on 32-bit linux on
distros that used 4k stacks - and perhaps there mostly where lvm/md/nfs
layers were also involved.

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