RE: superblock Q/clarification
David Cooley wrote: When I first set up my Raid 5, I made the partitions with Fdisk, and started /dev/hdc1 at block 0, the end was the end of the disk (single partition per drive except /dev/hdc5 is type whole disk). It ran fine until I rebooted, when it came up and said there was no valid superblock. I re-fdisked the drives and re-ran mkraid and all was well until I rebooted. I read somewhere (can't remember where though) that block 0 had to be isolated as the superblock was written there... I re-fdisked all my drives so partition /dev/hdx1 started at block 1 instead of zero and haven't had a problem since. I'm running Kernel 2.2.12 with raidtools 0.90 and all the patches.. I had a similar experience in setting up Raid 1 devices. Same Kernel and patches. Now my raid disks have nothing in block 0. For a while, I was using mismatched raid kernel and raidtools patches, so that might have been the point where I tried this solution. Bob Gerrish
superblock Q/clarification
My impression was that the s/w raid code only wrote to the ends (last 4k) of each device, so I'm trying to clarify the following paragraph from http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/Software-RAID.HOWTO-4.html#ss4.7 The persistent superblocks solve these problems. When an array is initialized with the persistent-superblock option in the /etc/raidtab file, a special superblock is written in the *beginning* of all disks participating in the array. This allows the kernel to read the configuration of RAID devices directly from the disks involved, instead of reading from some configuration file that may not be available at all times. Is the paragraph wrong or am I misunderstanding persistent superblocks? Thanks, James -- Miscellaneous Engineer --- IBM Netfinity Performance Development
Re: superblock Q/clarification
On Thu, Nov 04, 1999 at 08:09:31AM -0500, James Manning wrote:
My impression was that the s/w raid code only wrote to the ends (last 4k)
of each device, so I'm trying to clarify the following paragraph from
http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/Software-RAID.HOWTO-4.html#ss4.7
The persistent superblocks solve these problems. When an
array is initialized with the persistent-superblock option in
the /etc/raidtab file, a special superblock is written in the
*beginning* of all disks participating in the array. This allows the
It's a bug !
The superblocks are written in the end of all disks. I'll fix this in
the HOWTO ASAP.
kernel to read the configuration of RAID devices directly from
the disks involved, instead of reading from some configuration
file that may not be available at all times.
Is the paragraph wrong or am I misunderstanding persistent superblocks?
I can't believe I actually wrote *beginning* in the HOWTO... I should
know where the superblocks are... :)
Thanks,
--
: [EMAIL PROTECTED] : And I see the elder races, :
:.: putrid forms of man:
: Jakob Østergaard : See him rise and claim the earth, :
:OZ9ABN : his downfall is at hand. :
:.:{Konkhra}...:
Re: superblock Q/clarification
At 03:17 PM 11/4/1999 +0100, Jakob Østergaard wrote: On Thu, Nov 04, 1999 at 08:09:31AM -0500, James Manning wrote: My impression was that the s/w raid code only wrote to the ends (last 4k) of each device, so I'm trying to clarify the following paragraph from http://ostenfeld.dk/~jakob/Software-RAID.HOWTO/Software-RAID.HOWTO-4.html#ss4.7 The persistent superblocks solve these problems. When an array is initialized with the persistent-superblock option in the /etc/raidtab file, a special superblock is written in the *beginning* of all disks participating in the array. This allows the It's a bug ! The superblocks are written in the end of all disks. I'll fix this in the HOWTO ASAP. Does this mean we no longer have to start raid partitions at block 1 instead of block zero? === David Cooley N5XMT Internet: [EMAIL PROTECTED] Packet: N5XMT@KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068 We are Borg... Prepare to be assimilated! ===
Re: superblock Q/clarification
On Thu, Nov 04, 1999 at 10:01:41AM -0500, David Cooley wrote:
...
Does this mean we no longer have to start raid partitions at block 1
instead of block zero?
I'm sorry, but I have no idea of what you're referring to...
When accessing the RAID device you can't see that there is a superblock
at all. You can't access the superblock via valid accesses to the MD
device.
I might be misunderstanding your question... When did you ever have to
start anything at block 1 instead of block 0 ?
(Gee, I hope this isn't in the HOWTO as well ;)
--
: [EMAIL PROTECTED] : And I see the elder races, :
:.: putrid forms of man:
: Jakob Østergaard : See him rise and claim the earth, :
:OZ9ABN : his downfall is at hand. :
:.:{Konkhra}...:
Re: superblock Q/clarification
[ Thursday, November 4, 1999 ] David Cooley wrote: Does this mean we no longer have to start raid partitions at block 1 instead of block zero? Just out of curiosity, when was this the case? I've done s/w raid's on drives (not making partitions, so I lost autorun unfortunately) and never had a problem... James -- Miscellaneous Engineer --- IBM Netfinity Performance Development
Re: superblock Q/clarification
When I first set up my Raid 5, I made the partitions with Fdisk, and
started /dev/hdc1 at block 0, the end was the end of the disk (single
partition per drive except /dev/hdc5 is type whole disk).
It ran fine until I rebooted, when it came up and said there was no valid
superblock. I re-fdisked the drives and re-ran mkraid and all was well
until I rebooted. I read somewhere (can't remember where though) that
block 0 had to be isolated as the superblock was written there... I
re-fdisked all my drives so partition /dev/hdx1 started at block 1 instead
of zero and haven't had a problem since.
I'm running Kernel 2.2.12 with raidtools 0.90 and all the patches..
At 04:17 PM 11/4/1999 +0100, Jakob Østergaard wrote:
On Thu, Nov 04, 1999 at 10:01:41AM -0500, David Cooley wrote:
...
Does this mean we no longer have to start raid partitions at block 1
instead of block zero?
I'm sorry, but I have no idea of what you're referring to...
When accessing the RAID device you can't see that there is a superblock
at all. You can't access the superblock via valid accesses to the MD
device.
I might be misunderstanding your question... When did you ever have to
start anything at block 1 instead of block 0 ?
(Gee, I hope this isn't in the HOWTO as well ;)
--
: [EMAIL PROTECTED] : And I see the elder races, :
:.: putrid forms of man:
: Jakob Østergaard : See him rise and claim the earth, :
:OZ9ABN : his downfall is at hand. :
:.:{Konkhra}...:
===
David Cooley N5XMT Internet: [EMAIL PROTECTED]
Packet: N5XMT@KQ4LO.#INT.NC.USA.NA T.A.P.R. Member #7068
We are Borg... Prepare to be assimilated!
===
RE: superblock Q/clarification
Does this mean we no longer have to start raid partitions at block 1
instead of block zero?
I'm sorry, but I have no idea of what you're referring to...
See David's messages of 17/09/99 in the "Problem with mkraid for /dev/md0"
thread. David's curious experience and resulting misconception was left
unresolved, from what I can remember. Hence the continued confusion. Is the
original experience detailed in those messages anything to do with the fact that
David's system is Sparc-based? Or something to do with having to specify disk
geometry at boot-time? I don't know, but it's nothing to do with a limitation of
RAID.
Anyway, the simple answer is no. The new-style RAID superblocks have always been
at the end of the partitions, so this typo changes nothing in practice.
Cheers,
Bruno Prior [EMAIL PROTECTED]
-Original Message-
From: [EMAIL PROTECTED]
[mailto:[EMAIL PROTECTED]]On Behalf Of Jakob Østergaard
Sent: 04 November 1999 15:17
To: [EMAIL PROTECTED]
Subject: Re: superblock Q/clarification
On Thu, Nov 04, 1999 at 10:01:41AM -0500, David Cooley wrote:
...
Does this mean we no longer have to start raid partitions at block 1
instead of block zero?
I'm sorry, but I have no idea of what you're referring to...
When accessing the RAID device you can't see that there is a superblock
at all. You can't access the superblock via valid accesses to the MD
device.
I might be misunderstanding your question... When did you ever have to
start anything at block 1 instead of block 0 ?
(Gee, I hope this isn't in the HOWTO as well ;)
--
: [EMAIL PROTECTED] : And I see the elder races, :
:.: putrid forms of man:
: Jakob Østergaard : See him rise and claim the earth, :
:OZ9ABN : his downfall is at hand. :
:.:{Konkhra}...:
Re: superblock Q/clarification
[ Thursday, November 4, 1999 ] David Cooley wrote: Does this mean we no longer have to start raid partitions at block 1 instead of block zero? Just out of curiosity, when was this the case? I've done s/w raid's on drives (not making partitions, so I lost autorun unfortunately) and never had a problem... James -- Miscellaneous Engineer --- IBM Netfinity Performance Development
Re: superblock Q/clarification
David Cooley wrote: It's probably something to do with the fact that I'm on a Sparc Ultra 2 machine running Linux. Didn't think Linux saw the drives differently between platforms, but I guess it does. I'm guessing the drives were orginally used under Solaris/SunOS? i.e. they had a Sun disk label on them? I had the exact same problem (RAID5 was fine until I rebooted.. then they were reported as 'not a valid partition'). These were disks I used on a PC, but had salvaged them from work where they had been used on Suns. AFAIK the problem is in the Sun label. The way to fix it was to delete all partitions, write the label, exit fdisk, restart fdisk, and make a new empty DOS partition table. If you're wondering, I found it didn't work right if I didn't write the label, quit and restart before making the empty DOS label. I've also noticed that after you make the DOS label, it then does start from cylinder 1 instead of 0... maybe that's where that line of thought came from. -- Mike Marion - Unix SysAdmin/Engineer, Qualcomm Inc. Black holes are where God divided by zero.
