Debian Bug report logs - #593658
default compression=on?

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Package: zfsutils; Maintainer for zfsutils is GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>; Source for zfsutils is src:zfsutils.

Reported by: Tuco <tuco.xyz@gmail.com>

Date: Fri, 20 Aug 2010 00:57:01 UTC

Severity: wishlist

Tags: patch

Found in version zfsutils/8.1-3

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Report forwarded to debian-bugs-dist@lists.debian.org, GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>:
Bug#593658; Package zfsutils. (Fri, 20 Aug 2010 00:57:04 GMT) Full text and rfc822 format available.

Acknowledgement sent to Tuco <tuco.xyz@gmail.com>:
New Bug report received and forwarded. Copy sent to GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>. (Fri, 20 Aug 2010 00:57:04 GMT) Full text and rfc822 format available.

Message #5 received at submit@bugs.debian.org (full text, mbox):

From: Tuco <tuco.xyz@gmail.com>
To: submit <submit@bugs.debian.org>
Subject: default compression=on?
Date: Thu, 19 Aug 2010 20:55:22 -0400
[Message part 1 (text/plain, inline)]
Package: zfsutils
Version: 8.1-3
Tags: patch

Compression in ZFS has a triple benefit in IO performance, disk space
and energy consumption, this article explains (with benchmarks):
http://blogs.sun.com/partnertech/entry/zfs_compression_perf_disk_space

IO improvement isn't obvious: reading and writing takes less time when
compressing or decompressing because CPU is not the bottleneck. The
linked article explains in more detail.

I suggest enabling compression by default when creating new ZFS filesystems.
[compress.diff (text/x-diff, attachment)]

Information forwarded to debian-bugs-dist@lists.debian.org, GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>:
Bug#593658; Package zfsutils. (Fri, 20 Aug 2010 01:33:03 GMT) Full text and rfc822 format available.

Acknowledgement sent to Brett Dikeman <brett.dikeman@gmail.com>:
Extra info received and forwarded to list. Copy sent to GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>. (Fri, 20 Aug 2010 01:33:03 GMT) Full text and rfc822 format available.

Message #10 received at submit@bugs.debian.org (full text, mbox):

From: Brett Dikeman <brett.dikeman@gmail.com>
To: Tuco <tuco.xyz@gmail.com>, 593658@bugs.debian.org
Cc: submit <submit@bugs.debian.org>
Subject: Re: Bug#593658: default compression=on?
Date: Thu, 19 Aug 2010 21:30:33 -0400
On Thu, Aug 19, 2010 at 8:55 PM, Tuco <tuco.xyz@gmail.com> wrote:

> I suggest enabling compression by default when creating new ZFS filesystems.

I suggest giving the user the option during an install, if ZFS is
supported in that phase.  That has a definite benefit, as ZFS only
compresses data that makes it to disk after compression is flipped on.
 Turning on compression after an install is, at least for things like
/usr, largely pointless; eventually, as packages get updated etc, more
and more of the filesystem will become compressed, but...

Point worth noting: it's only of value if the data you have is by and
large compressable!  If you're a photographer and work with mostly RAW
and JPEGs, compression is going to be a waste of CPU cycles and maybe
(this is a wild guess) increase CPU cache misses?

It'd probably be worth talking to the ZFS developers to find out why
compression isn't enabled by default in Solaris/OpenSolaris.  They
probably had some logic behind it, and it might be relevant.

-B




Information forwarded to debian-bugs-dist@lists.debian.org, GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>:
Bug#593658; Package zfsutils. (Fri, 20 Aug 2010 01:33:05 GMT) Full text and rfc822 format available.

Acknowledgement sent to Brett Dikeman <brett.dikeman@gmail.com>:
Extra info received and forwarded to list. Copy sent to GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>. (Fri, 20 Aug 2010 01:33:05 GMT) Full text and rfc822 format available.

Information forwarded to debian-bugs-dist@lists.debian.org, GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>:
Bug#593658; Package zfsutils. (Fri, 20 Aug 2010 09:33:05 GMT) Full text and rfc822 format available.

Acknowledgement sent to Aurelien Jarno <aurelien@aurel32.net>:
Extra info received and forwarded to list. Copy sent to GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>. (Fri, 20 Aug 2010 09:33:05 GMT) Full text and rfc822 format available.

Message #20 received at 593658@bugs.debian.org (full text, mbox):

From: Aurelien Jarno <aurelien@aurel32.net>
To: Brett Dikeman <brett.dikeman@gmail.com>, 593658@bugs.debian.org
Cc: Tuco <tuco.xyz@gmail.com>
Subject: Re: Bug#593658: default compression=on?
Date: Fri, 20 Aug 2010 11:30:19 +0200
Brett Dikeman a écrit :
> On Thu, Aug 19, 2010 at 8:55 PM, Tuco <tuco.xyz@gmail.com> wrote:
> 
>> I suggest enabling compression by default when creating new ZFS filesystems.
> 
> I suggest giving the user the option during an install, if ZFS is
> supported in that phase.  That has a definite benefit, as ZFS only
> compresses data that makes it to disk after compression is flipped on.
>  Turning on compression after an install is, at least for things like
> /usr, largely pointless; eventually, as packages get updated etc, more
> and more of the filesystem will become compressed, but...
> 
> Point worth noting: it's only of value if the data you have is by and
> large compressable!  If you're a photographer and work with mostly RAW
> and JPEGs, compression is going to be a waste of CPU cycles and maybe
> (this is a wild guess) increase CPU cache misses?
> 
> It'd probably be worth talking to the ZFS developers to find out why
> compression isn't enabled by default in Solaris/OpenSolaris.  They
> probably had some logic behind it, and it might be relevant.
> 

I agree that enabling it by default without understanding all the
benefits/drawback is not something that should be done. Especially if
the default is different that what user expect (it is not the default on
OpenSolaris/FreeBSD, btrfs compression is disabled by default).

The best would indeed be to provide a way to create ZFS partitions
during the installation. Currently this is not the case, and there is
some work to do here. It is probably not straightforward, as you first
need to create a pool, then a filesystem. It's probably comparable to an
LVM installation in some senses. If someone wants to start working on
partman-zfs, please note that the zfsutils-udeb is available, and that a
patch for parted has been posted on the parted-devel mailing-list.

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net




Severity set to 'wishlist' from 'normal' Request was from Aurelien Jarno <aurel32@debian.org> to control@bugs.debian.org. (Fri, 20 Aug 2010 09:33:06 GMT) Full text and rfc822 format available.

Information forwarded to debian-bugs-dist@lists.debian.org, GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>:
Bug#593658; Package zfsutils. (Fri, 20 Aug 2010 15:57:03 GMT) Full text and rfc822 format available.

Acknowledgement sent to Ivan Jager <aij+@mrph.org>:
Extra info received and forwarded to list. Copy sent to GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>. (Fri, 20 Aug 2010 15:57:03 GMT) Full text and rfc822 format available.

Message #27 received at 593658@bugs.debian.org (full text, mbox):

From: Ivan Jager <aij+@mrph.org>
To: Brett Dikeman <brett.dikeman@gmail.com>, 593658@bugs.debian.org
Cc: Tuco <tuco.xyz@gmail.com>
Subject: Re: Bug#593658: default compression=on?
Date: Fri, 20 Aug 2010 11:48:42 -0400
On Thu, Aug 19, 2010 at 09:30:33PM -0400, Brett Dikeman scribbled:
> On Thu, Aug 19, 2010 at 8:55 PM, Tuco <tuco.xyz@gmail.com> wrote:
> 
> > I suggest enabling compression by default when creating new ZFS filesystems.
> 
> I suggest giving the user the option during an install, if ZFS is

I suggest running more benchmarks before suggesting the default
should be changed. :) The benchmark in question was measuring the
time and energy used while copying a file already on the same
filesystem, on some unspecified laptop. Do we really want to
optimize for copying files on an otherwise idle computer with a
slow disk while completely ignoring any effects this might have
on desktops, servers, or computers that are actually doing
something?

BTW, I expect deduplication would have a much more drastic effect
on this benchmark. We should turn it on by default. /s
 
> It'd probably be worth talking to the ZFS developers to find out why
> compression isn't enabled by default in Solaris/OpenSolaris.  They
> probably had some logic behind it, and it might be relevant.

My guess would be that they are optimizing for computers that
actually compute things. Another reason might be that if the
filesystem explodes it is easier to recover uncompressed files,
although I get the feeling ZFS developers like to think that
would never be necessary. But, yeah, it's probably worth checking
with them before changing the default.

Ivan




Information forwarded to debian-bugs-dist@lists.debian.org, GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>:
Bug#593658; Package zfsutils. (Tue, 07 Sep 2010 18:15:06 GMT) Full text and rfc822 format available.

Acknowledgement sent to "Witold Baryluk" <baryluk@smp.if.uj.edu.pl>:
Extra info received and forwarded to list. Copy sent to GNU/kFreeBSD Maintainers <debian-bsd@lists.debian.org>. (Tue, 07 Sep 2010 18:15:06 GMT) Full text and rfc822 format available.

Message #32 received at 593658@bugs.debian.org (full text, mbox):

From: "Witold Baryluk" <baryluk@smp.if.uj.edu.pl>
To: 593658@bugs.debian.org
Subject: Re: default compression=on?
Date: Tue, 7 Sep 2010 20:03:51 +0200
[Message part 1 (text/plain, inline)]
Please do not change default of compression.

I have compression enabled on most of my datasets, but
it really should not be default. This can break existings
assumptions and scripts (for example from solaris or freebsd).

Much better would be change debian-installer to
create dataset with compression as an option.
Also things like copies=2 can be added to debian-installer,
as it can be very usefull for system data, especially
if we are installing on single disk (i.e. laptop).
But nobody is suggesting makeing copies=2 a default for zfs create.

If people will want to enable compression they will enabled it,
when they find it beneficial.

If there are anyone making compression=on a default,
i would only think as upstream to make this decision after
extremly extensive testing as it needs lots of knowledge
to state that it do not introduce considerable regressions.


Just my $.02


-- 
Witold Baryluk
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