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Conventional Wisdom Watch

 

 

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ylee at pobox

Jan 18, 2006, 1:39 PM

Post #1 of 4 (826 views)
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Conventional Wisdom Watch

Michael Haan <michael.haan [at] gmail> says:
> Ok, so I'm not sure what the consensus is. My distro is FC4, kernel is
> 2.6.14 from ATrpms. My main partition is ext3 everything else is on
> ReiserFS/RAID device. So, is the suggestion for me to rebuild my kernel, or
> remake the RAID FS using XFS or JFS, or some combination of the two?

Conventional Wisdom Watch (with apologies to Newsweek)

Rebuild kernel <> Good: Old 8K stack option restores stability to
multiple filesystem layers. Bad: You'd
better know how to manually roll your own
kernel or at the least edit and rebuild
source RPMs.
ReiserFS V Many people swear by it, but many others
swear at it, especially when dealing with
gigabyte-sized files of the kind MythTV
produces. Why take the chance?
XFS ^ Balanced read/write performance. But
is it true that the kernel maintainers
dislike it?
JFS ^ Back by full faith and credit of one of the
largest IT companies on Earth. Writes not quite
as good as reads, though.
Ext3 <> Reliable, rock-solid, battle-proven, and no
hours-lonk fsck. But slow, slow, slow, slow.
LVM2 ^ Flexibility makes extending or modifying
partitions easy. But be prepared for the
performance hit.

--
Yeechang Lee <ylee [at] pobox> | +1 650 776 7763 | San Francisco CA US
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beww at beww

Jan 18, 2006, 2:36 PM

Post #2 of 4 (796 views)
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Re: Conventional Wisdom Watch [In reply to]

On Jan 18, 2006, at 2:39 PM, Yeechang Lee wrote:

> Michael Haan <michael.haan [at] gmail> says:
>> Ok, so I'm not sure what the consensus is. My distro is FC4,
>> kernel is
>> 2.6.14 from ATrpms. My main partition is ext3 everything else is on
>> ReiserFS/RAID device. So, is the suggestion for me to rebuild my
>> kernel, or
>> remake the RAID FS using XFS or JFS, or some combination of the two?
>
> Conventional Wisdom Watch (with apologies to Newsweek)
>
> Rebuild kernel <> Good: Old 8K stack option restores
> stability to
> multiple filesystem layers. Bad: You'd
> better know how to manually roll your own
> kernel or at the least edit and rebuild
> source RPMs.
> ReiserFS V Many people swear by it, but many others
> swear at it, especially when dealing with
> gigabyte-sized files of the kind MythTV
> produces. Why take the chance?
> XFS ^ Balanced read/write performance. But
> is it true that the kernel maintainers
> dislike it?
> JFS ^ Back by full faith and credit of one of the
> largest IT companies on Earth. Writes not quite
> as good as reads, though.
> Ext3 <> Reliable, rock-solid, battle-proven, and no
> hours-lonk fsck. But slow, slow, slow, slow.
> LVM2 ^ Flexibility makes extending or modifying
> partitions easy. But be prepared for the
> performance hit.

Good summary.

Remember, though, that the PC Jr., Microchannel Architecture and OS/2
were also "backed by the full faith and credit of one of the largest..."

Having said that, I run JFS on a software RAID0 and have no problems
at all.
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johnbiundo at sbcglobal

Jan 18, 2006, 2:50 PM

Post #3 of 4 (827 views)
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Re: Conventional Wisdom Watch [In reply to]

Yeechang Lee wrote:
> LVM2 ^ Flexibility makes extending or modifying
> partitions easy. But be prepared for the
> performance hit.

Interesting post. How might the LVM2 performance hit manifest itself?
Could it be the source of some strangeness I'm seeing with pre-buffering
pauses?

Also related to your filesystem comments: might jfs NOT be a great
choice for the ringbuffer? I've got it on its own jfs partition now.
10GB. Should I consider switching that to reiserfs or xfs?

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ylee at pobox

Jan 18, 2006, 4:55 PM

Post #4 of 4 (796 views)
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Re: Conventional Wisdom Watch [In reply to]

John Biundo <johnbiundo [at] sbcglobal> says:
> Interesting post. How might the LVM2 performance hit manifest
> itself? Could it be the source of some strangeness I'm seeing with
> pre-buffering pauses?

I can't speak to your particular situation. All I know is that my
local read and write speeds on an eight-spindle,
JFS-on-LVM2-on-(single) software RAID 5 went up by several multiples
when I made the sole change of removing LVM2 from the equation. I have
previously noted here that none of the several large-scale academic
RAID arrays that most resemble my setup uses LVM2.

> Also related to your filesystem comments: might jfs NOT be a great
> choice for the ringbuffer? I've got it on its own jfs partition
> now. 10GB. Should I consider switching that to reiserfs or xfs?

I based my comment on what several comparative benchmarks I've read
reported regarding XFS versus JFS (all of them also noting that the
differences weren't that great) and the feeling that I should say
*something* negative about JFS. On the other hand, when I removed LVM2
on my array as mentioned above I did briefly try XFS, only to find
that bonnie++ reported speeds about two thirds that of JFS's, so I
reverted to what I knew best.

I was quite serious about ReiserFS; in my experience it is definitely
the filesystem people love to hate as much as love. XFS and JFS get
plaudits from pretty much everyone who uses them, albeit with the
occasional caveat that they as of yet do not have *on Linux* the
real-life performance lifetimes that ext2 and ext3 do.

--
Yeechang Lee <ylee [at] pobox> | +1 650 776 7763 | San Francisco CA US
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