9:32 p.m.
The Fedora installer has insisted on requiring four drives for raid-10 install,
and then not using raid-10, but rather raid-1+0 which is *NOT* the same thing.
Any hope that this could be fixed in fc10, as it is a real PITA to fight a way
around it and get a proper raid configured.
This is a real performance issue, see linux-raid discussion in archives about this.
--
Bill Davidsen <davidsen(a)tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
9:39 p.m.
Bill Davidsen wrote:
The Fedora installer has insisted on requiring four drives for
raid-10
install, and then not using raid-10, but rather raid-1+0 which is *NOT*
the same thing.
http://en.wikipedia.org/wiki/RAID#Nested_levels
-Jeroen
10:31 a.m.
Jeroen van Meeuwen wrote:
Bill Davidsen wrote:
> The Fedora installer has insisted on requiring four drives for raid-10
> install, and then not using raid-10, but rather raid-1+0 which is
> *NOT* the same thing.
http://en.wikipedia.org/wiki/RAID#Nested_levels
ah, but...
http://en.wikipedia.org/wiki/Non-standard_RAID_levels
See the Linux MD RAID 10 section.
(or man md, if you'd prefer)
It is still (at its most basic) effectively RAID 1+0, but doesn't
require an even number of disks and can do some funky things with layout
and number of (near or far) copies of each chunk.
this is what
mdadm -C /dev/md0 -l 10 -n4 /dev/sd{a,b,c,d}1
would do, for example.
As opposed to manually creating 2 mirrors and striping over them.
Stuart
--
Stuart Sears RHCA etc.
"It's today!" said Piglet.
"My favourite day," said Pooh.
11:09 a.m.
Stuart Sears wrote:
Jeroen van Meeuwen wrote:
> Bill Davidsen wrote:
>> The Fedora installer has insisted on requiring four drives for raid-10
>> install, and then not using raid-10, but rather raid-1+0 which is
>> *NOT* the same thing.
> http://en.wikipedia.org/wiki/RAID#Nested_levels
ah, but...
http://en.wikipedia.org/wiki/Non-standard_RAID_levels
See the Linux MD RAID 10 section.
(or man md, if you'd prefer)
Ah, that RAID-10 ;-)
It's naming is a little confusing; RAID-10 (as used by the installer) is
what the installer uses to create RAID-1+0 (commonly referred to as
RAID-10, but indeed just "mirroring a stripeset" (1+0), but in one
single layer (10)), and hence requires 4 disks.
There's no RAID-10 in the installer as you refer to just like there is
no RAID LVM configuration, and whatnot. The installer is a helper
program to make the initial configuration for a new installation a
breeze, not to make sure it has every little checkbox for every possible
option.
If this isn't the appropriate configuration for you, then maybe
switching to the console on tty2 and creating the MD yourself or
providing a kickstart file with the correct %pre script solves the problem.
Don't get me wrong, it *could* be a very nice feature to add to the
installer, but then again we *must* prevent the installer from being
obfuscated for normal users.
Kind regards,
Jeroen van Meeuwen
-kanarip
2:22 p.m.
Jeroen van Meeuwen wrote:
Stuart Sears wrote:
> Jeroen van Meeuwen wrote:
>> Bill Davidsen wrote:
>>> The Fedora installer has insisted on requiring four drives for raid-10
>>> install, and then not using raid-10, but rather raid-1+0 which is
>>> *NOT* the same thing.
>> http://en.wikipedia.org/wiki/RAID#Nested_levels
>
> ah, but...
>
> http://en.wikipedia.org/wiki/Non-standard_RAID_levels
>
> See the Linux MD RAID 10 section.
> (or man md, if you'd prefer)
>
Ah, that RAID-10 ;-)
It's naming is a little confusing; RAID-10 (as used by the installer) is
what the installer uses to create RAID-1+0 (commonly referred to as
RAID-10, but indeed just "mirroring a stripeset" (1+0), but in one
single layer (10)), and hence requires 4 disks.
There's no RAID-10 in the installer as you refer to just like there is
no RAID LVM configuration, and whatnot. The installer is a helper
program to make the initial configuration for a new installation a
breeze, not to make sure it has every little checkbox for every possible
option.
If this isn't the appropriate configuration for you, then maybe
switching to the console on tty2 and creating the MD yourself or
providing a kickstart file with the correct %pre script solves the problem.
The problem is that there is a "raid10" entry in the raid part of the
installer.
And since this is being done by the software raid, it's confusing to have raid10
mean one thing to the installer and another in the man pages and to the man who
maintains the code. I would like raid10 to be raid10, I would settle to have the
installer call it raid1+0 to use the correct terminology.
Don't get me wrong, it *could* be a very nice feature to add to
the
installer, but then again we *must* prevent the installer from being
obfuscated for normal users.
My point exactly, if the raid10 in the installer doesn't mean the same thing
as
the raid code and the raid man pages, it confuses the hell out of the users. Not
to mention that there's no clean way to get to the raid10 supported by the
kernel, which allows any number of drives >1, and considerably better
performance with -f2 used for swap.
--
Bill Davidsen <davidsen(a)tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
3:24 p.m.
Bill Davidsen wrote:
The problem is that there is a "raid10" entry in the raid
part of the
installer. And since this is being done by the software raid, it's
confusing to have raid10 mean one thing to the installer and another in
the man pages and to the man who maintains the code. I would like raid10
to be raid10, I would settle to have the installer call it raid1+0 to
use the correct terminology.
That could be a fairly simple path to the installer, then.
Kind regards,
Jeroen van Meeuwen
-kanarip
11 a.m.
On Saturday 27 September 2008 09:32:27 pm Bill Davidsen wrote:
The Fedora installer has insisted on requiring four drives for
raid-10
install, and then not using raid-10, but rather raid-1+0 which is *NOT* the
same thing. Any hope that this could be fixed in fc10, as it is a real PITA
to fight a way around it and get a proper raid configured.
This is a real performance issue, see linux-raid discussion in archives
about this.
--
Bill Davidsen <davidsen(a)tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
Raid 10 requires at least 4
drives. and then it needs even numbers of disks to
grow. so you could do 4,6,8,10,12 etc. an odd disk is should only be used
as a hot spare. otherwise it would cause degregation to the array
md1 : active raid10 sda2[0] sdd2[3] sdc2[2] sdb2[1]
624623104 blocks 256K chunks 2 near-copies [4/4] [UUUU]
looks like its right to me. this box was installed F-8 and was yum updated
to rawhide. my box with raid 10 is using the raid 10 module. i have
4x320gb drives and get great performance out of the array.
hdparm -tT /dev/md1
/dev/md1:
Timing cached reads: 4868 MB in 1.99 seconds = 2441.54 MB/sec
Timing buffered disk reads: 256 MB in 3.02 seconds = 84.75 MB/sec
Dennis
2:26 p.m.
Dennis Gilmore wrote:
On Saturday 27 September 2008 09:32:27 pm Bill Davidsen wrote:
> The Fedora installer has insisted on requiring four drives for raid-10
> install, and then not using raid-10, but rather raid-1+0 which is *NOT* the
> same thing. Any hope that this could be fixed in fc10, as it is a real PITA
> to fight a way around it and get a proper raid configured.
>
> This is a real performance issue, see linux-raid discussion in archives
> about this.
>
Raid 10 requires at least 4 drives. and then it needs even numbers of
disks to
grow. so you could do 4,6,8,10,12 etc. an odd disk is should only be used
as a hot spare. otherwise it would cause degregation to the array
As I said, raid10 is not the same thing as raid1+0. And since the kernel and
installer use the same term for different things, I would say the install should
match the kernel code and doc, and not have the user confused. Using the correct
term for what the installer really does, raid1+0, would confuse no one.
The man pages for raid and mdadm are helpful in understanding the difference
between 1+0 and 10.
md1 : active raid10 sda2[0] sdd2[3] sdc2[2] sdb2[1]
624623104 blocks 256K chunks 2 near-copies [4/4] [UUUU]
looks like its right to me. this box was installed F-8 and was yum updated
to rawhide. my box with raid 10 is using the raid 10 module. i have
4x320gb drives and get great performance out of the array.
hdparm -tT /dev/md1
/dev/md1:
Timing cached reads: 4868 MB in 1.99 seconds = 2441.54 MB/sec
Timing buffered disk reads: 256 MB in 3.02 seconds = 84.75 MB/sec
Dennis
--
Bill Davidsen <davidsen(a)tmr.com>
"We have more to fear from the bungling of the incompetent than from
the machinations of the wicked." - from Slashdot
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7 comments
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participants (4)
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Bill Davidsen -
Dennis Gilmore -
Jeroen van Meeuwen -
Stuart Sears