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- Q:
What is the current best known-stable patch for RAID in the
2.0.x series kernels?
A:
As of 18 Sept 1997, it is
"2.0.30 + pre-9 2.0.31 + Werner Fink's swapping patch
+ the alpha RAID patch". As of November 1997, it is
2.0.31 + ... !?
- Q:
The RAID patches will not install cleanly for me. What's wrong?
A:
Make sure that /usr/include/linux is a symbolic link to
/usr/src/linux/include/linux .
Make sure that the new files raid5.c , etc.
have been copied to their correct locations. Sometimes
the patch command will not create new files. Try the
-f flag on patch .
- Q:
While compiling raidtools 0.42, compilation stops trying to
include <pthread.h> but it doesn't exist in my system.
How do I fix this?
A:
raidtools-0.42 requires linuxthreads-0.6 from:
ftp://ftp.inria.fr/INRIA/Projects/cristal/Xavier.Leroy
Alternately, use glibc v2.0.
- Q:
I get the message:
mdrun -a /dev/md0: Invalid argument
A:
Use mkraid to initialize the RAID set prior to the first use.
mkraid ensures that the RAID array is initially in a
consistent state by erasing the RAID partitions. In addition,
mkraid will create the RAID superblocks.
- Q:
I get the message:
mdrun -a /dev/md0: Invalid argument
The setup was:
A:
Try lsmod (or, alternately, cat
/proc/modules ) to see if the raid modules are loaded.
If they are not, you can load them explicitly with
the modprobe raid1 or modprobe raid5
command. Alternately, if you are using the autoloader,
and expected kerneld to load them and it didn't
this is probably because your loader is missing the info to
load the modules. Edit /etc/conf.modules and add
the following lines:
alias md-personality-3 raid1
alias md-personality-4 raid5
- Q:
While doing
mdadd -a I get the error:
/dev/md0: No such file or directory . Indeed, there
seems to be no /dev/md0 anywhere. Now what do I do?
A:
The raid-tools package will create these devices when
you run make install as root. Alternately,
you can do the following:
cd /dev
./MAKEDEV md
- Q:
After creating a raid array on
/dev/md0 ,
I try to mount it and get the following error:
mount: wrong fs type, bad option, bad superblock on /dev/md0,
or too many mounted file systems . What's wrong?
A:
You need to create a file system on /dev/md0
before you can mount it. Use mke2fs .
- Q:
Truxton Fulton wrote:
On my Linux 2.0.30 system, while doing a mkraid for a
RAID-1 device,
during the clearing of the two individual partitions, I got
"Cannot allocate free page" errors appearing on the console,
and "Unable to handle kernel paging request at virtual address ..."
errors in the system log. At this time, the system became quite
unusable, but it appears to recover after a while. The operation
appears to have completed with no other errors, and I am
successfully using my RAID-1 device. The errors are disconcerting
though. Any ideas?
A:
This was a well-known bug in the 2.0.30 kernels. It is fixed in
the 2.0.31 kernel; alternately, fall back to 2.0.29.
- Q:
I'm not able to
mdrun a RAID-1, RAID-4 or RAID-5 device.
If I try to mdrun a mdadd 'ed device I get
the message ''invalid raid superblock magic ''.
A:
Make sure that you've run the mkraid part of the install
procedure.
- Q:
When I access
/dev/md0 , the kernel spits out a
lot of errors like md0: device not running, giving up !
and I/O error... . I've successfully added my devices to
the virtual device.
A:
To be usable, the device must be running. Use
mdrun -px /dev/md0 where x is l for linear, 0 for
RAID-0 or 1 for RAID-1, etc.
- Q:
I've created a linear md-dev with 2 devices.
cat /proc/mdstat shows
the total size of the device, but df only shows the size of the first
physical device.
A:
You must mkfs your new md-dev before using it
the first time, so that the filesystem will cover the whole device.
- Q:
I've set up
/etc/mdtab using mdcreate, I've
mdadd 'ed, mdrun and fsck 'ed
my two /dev/mdX partitions. Everything looks
okay before a reboot. As soon as I reboot, I get an
fsck error on both partitions: fsck.ext2: Attempt to read block from filesystem resulted in short
read while trying too open /dev/md0 . Why?! How do
I fix it?!
A:
During the boot process, the RAID partitions must be started
before they can be fsck 'ed. This must be done
in one of the boot scripts. For some distributions,
fsck is called from /etc/rc.d/rc.S , for others,
it is called from /etc/rc.d/rc.sysinit . Change this
file to mdadd -ar *before* fsck -A
is executed. Better yet, it is suggested that
ckraid be run if mdadd returns with an
error. How do do this is discussed in greater detail in
question 14 of the section ''Error Recovery''.
- Q:
I get the message
invalid raid superblock magic while
trying to run an array which consists of partitions which are
bigger than 4GB.
A:
This bug is now fixed. (September 97) Make sure you have the latest
raid code.
- Q:
I get the message
Warning: could not write 8 blocks in inode table starting at 2097175 while trying to run mke2fs on
a partition which is larger than 2GB.
A:
This seems to be a problem with mke2fs
(November 97). A temporary work-around is to get the mke2fs
code, and add #undef HAVE_LLSEEK to
e2fsprogs-1.10/lib/ext2fs/llseek.c just before the
first #ifdef HAVE_LLSEEK and recompile mke2fs.
- Q:
ckraid currently isn't able to read /etc/mdtab
A:
The RAID0/linear configuration file format used in
/etc/mdtab is obsolete, although it will be supported
for a while more. The current, up-to-date config files
are currently named /etc/raid1.conf , etc.
- Q:
The personality modules (
raid1.o ) are not loaded automatically;
they have to be manually modprobe'd before mdrun. How can this
be fixed?
A:
To autoload the modules, we can add the following to
/etc/conf.modules :
alias md-personality-3 raid1
alias md-personality-4 raid5
- Q:
I've
mdadd 'ed 13 devices, and now I'm trying to
mdrun -p5 /dev/md0 and get the message:
/dev/md0: Invalid argument
A:
The default configuration for software RAID is 8 real
devices. Edit linux/md.h , change
#define MAX_REAL=8 to a larger number, and
rebuild the kernel.
- Q:
I can't make
md work with partitions on our
latest SPARCstation 5. I suspect that this has something
to do with disk-labels.
A:
Sun disk-labels sit in the first 1K of a partition.
For RAID-1, the Sun disk-label is not an issue since
ext2fs will skip the label on every mirror.
For other raid levels (0, linear and 4/5), this
appears to be a problem; it has not yet (Dec 97) been
addressed.
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