Re: A gmirror question.

2008-10-29 Thread Stefan Moro
Ok, that explains it.

Thanks for the quick answers!

BR
Stefan
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A gmirror question.

2008-10-28 Thread Stefan Moro
Hi!

I've got a question regarding the way that gmirror identifies what
components (if that is the right term) are included in a mirror.

I recently created a mirror over two disks, ad2 and ad4. After some
bios changes (activating PATA) these devices were changed to ad6 and
ad10 respectively.
The magic thing (which probably isn't so magic =) ) here is that
after reboot, gmirror still managed to identify the mirror, now using
ad6 and ad10.

If I have understood things correctly, gmirror stores all relevant
information about the mirror in the last sector on the provider.

So I guess one possible solution is that gmirror ,during startup,
scans all disks/slices for this magic sector and then starts the
mirror.
But if this is the case, how does gmirror know that it should use (in
my example above) ad10 and not ad4 as the additional disk in the
mirror.
Or does gmirror use something else than the /dev entries to address disks??

I'm just curious how gmirror does this.


BR Stefan
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Re: A gmirror question.

2008-10-28 Thread Chris St Denis

Stefan Moro wrote:

Hi!

I've got a question regarding the way that gmirror identifies what
components (if that is the right term) are included in a mirror.

I recently created a mirror over two disks, ad2 and ad4. After some
bios changes (activating PATA) these devices were changed to ad6 and
ad10 respectively.
The magic thing (which probably isn't so magic =) ) here is that
after reboot, gmirror still managed to identify the mirror, now using
ad6 and ad10.

If I have understood things correctly, gmirror stores all relevant
information about the mirror in the last sector on the provider.

So I guess one possible solution is that gmirror ,during startup,
scans all disks/slices for this magic sector and then starts the
mirror.
But if this is the case, how does gmirror know that it should use (in
my example above) ad10 and not ad4 as the additional disk in the
mirror.
Or does gmirror use something else than the /dev entries to address disks??

I'm just curious how gmirror does this.


BR Stefan
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I don't know the technical details of the internal working of gmirror, 
but it likely uses the volume serial number or other such identifier.

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Re: A gmirror question.

2008-10-28 Thread Wojciech Puchar

If I have understood things correctly, gmirror stores all relevant
information about the mirror in the last sector on the provider.


exactly. it doesn't matter how the disks are connected.

all data is in last sector.

for non-mirrored drives it's useful to use glabel to get the same
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Re: A gmirror question.

2008-10-28 Thread Mel
On Tuesday 28 October 2008 17:53:20 Stefan Moro wrote:

 But if this is the case, how does gmirror know that it should use (in
 my example above) ad10 and not ad4 as the additional disk in the
 mirror.
 Or does gmirror use something else than the /dev entries to address disks??

 I'm just curious how gmirror does this.

It doesn't care about the device name. Geom modules that are loaded into the 
kernel, register a 'taste' function, with the geom(4) subsystem, that tastes 
if a provider is something they want to work with. Effectively, this taste 
function reads the last sector and checks if it has gmirror metadata.
The geom system is the 'magician', which basically hands all providers to the 
loaded modules.

-- 
Mel

Problem with today's modular software: they start with the modules
and never get to the software part.
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geom gmirror question

2007-12-06 Thread Dino Vliet
  Forwarded Message 

From:  Dino Vliet [EMAIL PROTECTED]CC:  [EMAIL PROTECTED]
To:  freebsd-questions@freebsd.orgDate:  Sat, 7 Apr 2007 03:55:20 -0700 
(PDT)Subject:  hardware problems?..how to disable geom?Plain Text 
Attachment [ Scan and Save to Computer ] 


Hi folks,I have sinned:-(I have (for testing purposes) activated geom 
for mirroring on my   freebsd 6.2 via c3 cpu system. However, I used two 
different brand IDE   harddisks but identical in capacity.I have:  ad0: 
76319MB MAXTOR STM3802110A 3.AAK at ata0-master UDMA100  ad3: 76319MB 
Seagate ST3802110A 3.AAJ at ata1-slave UDMA100At first everything worked, 
but lately I have noticed some weird   things:  1) In the beginning the gmirror 
status command was showing the complete   status for the components ad0 or ad3 
(it was altering I guess due to   the round robin thing I choose)   However 
since a few weeks, only the ad0 component shows the complete   status(the 
only thing I did in between was removing the seagate harddisk once   to try to 
go to a pc mall and buy a second one but when I returned I   just reattached it 
(I hadn't switched the pc on though in the mean time   so I don't think it's an 
issue))2) I started to have problems building the
 ports and make buildword3) bash core dumped on my (I couldn't log in 
nomaly anymore and had to   use csh)4) now I see that rsyncd, freshclam and 
clamav are core dumping when   the machine boots up:  GEOM_MIRROR: Device gm0: 
provider ad3 detected.  GEOM_MIRROR: Device gm0: provider ad3 activated.  
GEOM_MIRROR: Device gm0: provider ad0 activated.  GEOM_MIRROR: Device gm0: 
provider mirror/gm0 launched.  Trying to mount root from ufs:/dev/mirror/gm0s1a 
 pid 896 (rsync), uid 0: exited on signal 4 (core dumped)  pid 928 (clamd), uid 
0: exited on signal 4 (core dumped)  pid 934 (freshclam), uid 0: exited on 
signal 4 (core dumped)  So I want to bring the machine back to its normal 
state by doing this:a) remove seagate harddisk  b) remove the mirror  c) 
see if everything works fine again because I don't want to reinstall   (I CAN 
GET AWAY WITH THIS RIGHT?)The question is, how di I get rid of the mirror? 
Or is it better to   order a new seagate harddisk, get rid
 of the maxtor harddisk and install   the new seagate harddisk in stead of the 
maxtor one and rebuild the   mirror?Thanks for your kind help  
***

 

Hi folks,

 

I've bought my new hardware and want to give this another try. 

On the documentation sacttered around on the net I read that

it's better to have 3 harddisks where one is for the main os

and the other two are mirrored in stead of a situation where

the OS resides on one of the two mirrored disks.

Can you give me some advice on this?

I have three identical seagate harddisks and want to put two 

in a mirror setup with the OS on it, and use the other as 

spare drive, in case sonmething goes wrong.

 

Thanks in advanced

Dino Vliet

   
-
Never miss a thing.   Make Yahoo your homepage.
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Re: geom gmirror question

2007-12-06 Thread Eric Crist

On Dec 6, 2007, at 4:01 AM, Dino Vliet wrote:


Hi folks,

I've bought my new hardware and want to give this another try.
On the documentation sacttered around on the net I read that
it's better to have 3 harddisks where one is for the main os
and the other two are mirrored in stead of a situation where
the OS resides on one of the two mirrored disks.
Can you give me some advice on this?
I have three identical seagate harddisks and want to put two
in a mirror setup with the OS on it, and use the other as
spare drive, in case sonmething goes wrong.

Thanks in advanced
Dino Vliet



Dino,

We're running all of our firewalls now with gmirror.  Our setup uses a  
hot-swap SCSI setup, whereas you're using ATA disks.  Keep in mind  
that, to remove the drives, you'll more than likely need to shut down  
the system.  Have the third drive in there as a back up will certainly  
buy you time.


Follow the how-to I've written at https://www.secure-computing.net/wiki/index.php/Gmirror 
, and simply don't do any configuration on the third drive in the  
system.  When one fails, you'll then remove, or 'forget' the failed  
drive, and add in the hot-spare you've got in the system.


HTH
-
Eric F Crist
Secure Computing Networks


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