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A message to Daniel Robbins and other developers: |
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The exclusion of XFS support in the newest Gentoo kernel |
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hit many people by surprise: |
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"I've just released a brand-new gentoo-sources kernel. ... Please |
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note that this kernel has no XFS in it. I was able to really |
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enhance this kernel because I didn't have the huge XFS patch |
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to get in the way." -Daniel Robbins |
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I was stunned by the number of people who wished to take advantage |
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of the new performance enhancements in the newest Gentoo kernel, |
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and in order to do so, considered changing their entire filesystem |
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just to benefit from the newest kernel ! |
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Incredible, that for (at least) the past six months, XFS support |
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has been offered (and even 'encouraged' in the install docs), and |
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now people are wanting to change their filesystem (which isn't |
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trivial) because of someone's decision as to what to include in |
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the newest high-performance Gentoo kernel? |
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|
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(from the mailing lists) |
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"On this note, is there a "good" way to convert XFS to something else |
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like jfs or ext3 or whatever is in the default kernel?" |
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"Now I guess I have to reinstall to take advantage of the new gentoo |
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sources." |
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"So what are people choosing for a filesystem who want to use the |
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gentoo kernel?" |
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"I sure will be glad when the XFS code gets integrated with the |
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main kernel sources." |
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"Is there any way to convert an XFS partition to ext3 or even |
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ResierFS? ... the speed improvements of the preempt and such are |
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far more important to me then the benefits of XFS." |
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Having chosen a particular filesystem and then having to deal with |
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the consequences of not benefiting from the newest performance |
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enhancements is one issue. |
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Another issue is, if XFS as a filesystem which used to be supported |
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by the Gentoo (sys-kernel/linux-sources which no longer exists) kernel, |
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will be de-emphasized, then perhaps, the install docs should be changed |
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to reflect this (opposite) trend: |
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|
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(from the install documentation) |
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"XFS is a high-performance enterprise-class filesystem with metadata |
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journaling that is fully supported under Gentoo Linux." |
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If it's not currently false, then it's just a bit misleading to people |
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who are installing for the first time and haven't read all of the issues |
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discussed on the mailing lists. Perhaps, the issues surrounding XFS |
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and stability in recent kernels, and the likelihood? that the newest |
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performance tweaks may take longer to reach the (new) xfs-sources, should |
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be emphasized from the beginning. |
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It only when it's too late that people start realizing that the |
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filesystem that they've chosen doesn't correlate well with getting |
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the newest cutting-edge high-performance Gentoo kernels: |
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(from the mailing lists) |
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"The one drawback is that xfs patches are only available for certain |
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kernel releases" |
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"It is disheartening to see XFS being deemphesized by the distro. |
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... I would really like to have preempt and low latency back as |
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well, but am unwilling to give up what is hands down my favorite |
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filesystem in order to do so." |
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"If you can survive with the 2.4.18 kernel you can have the XFS |
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patch and the preempt patch at the same time" |
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What to make of all this? I'm in as much of a dilemma as many others, |
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and the first impulse was to create my own Gentoo kernel with all of |
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the performance and security patches + XFS (which seems to be simply an |
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image size issue--based on D. Robbin's "I was able to really enhance |
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this kernel because I didn't have the huge XFS patch to get in the way.", |
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rather than a stability issue). If XFS creates instability in the |
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newest kernel sources, this should be mentioned, since many people |
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will read the install documentation thinking the following excerpt |
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more or less means "stable": |
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(from the install documentation) |
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"If you're looking for a high-performance filesystem with journaling |
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support, use XFS; both ext3 and XFS are mature and refined." |
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>From the mailing list complaints/comments/questions, I have the |
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impression that creating such a kernel is not a trivial task. If it |
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is, could someone offer a HOWTO on constructing/patching such a |
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personalized Gentoo kernel so that many people won't have to rely |
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on or wait for the newest official Gentoo kernel that suits everyone's |
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setup? |
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If it is no trivial task, could we then change the install docs |
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to prevent others from choosing 'the wrong FS' for high-performance, |
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OR simply offer the non-XFS kernel version AND the XFS kernel version, |
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since it seems not to be a huge stability issue anymore. |
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Comments/discussion welcome. |
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/r. |
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