Hallo,
ich bin seit Jahren in der Verteilerliste und möchte daraus gelöscht werden.

Danke

To: partman@yahoogroups.com
From: aleca@...
Date: Thu, 27 Aug 2009 12:35:15 +0200
Subject: RE: [partman] HDD switching and Ranish restore























stock_market_player wrote on Wednesday, August 19, 2009 10:05 AM

> Subject: [partman] HDD switching and Ranish restore

>

> I currently have 3 HHDs in my computer and the 2nd one is

> dying and will be replaced. All of them are SATA drives. Only

> the first drive is a boot drive, the other 2 are storage/backups.

> They are 74GB, 500GB (dead one), 1024GB.

>

>

> Anyway, I'm fearfull that:

> 1) if I remove the 2nd harddrive and enter the RPM menu it

> will see that I only have 2 harddrives and will think that

> the 3rd harddrive is the 2nd one and will try to "fix" its

> partition table, corrupting it instead.



*UNLESS* you are using a strange setup of a customized version of Ranish

boot manager to boot directly to the 2nd or 3rd disk _and_ hiding some

other partitions meanwhile, it is very unlikely to have RPM writing

partition tables of the _other_ drives "automagically."



(Of course it is very easy to shot oneself in the foot and to edit the

wrong table: partition editors are dangerous tools, this is a known

fact.)



> (I was surprised to see that the device names changed in

> Linux when I unplugged my 2nd harddrive, even when I was

> using the same SATA connector... it seems it's the way SATA works)



No: that's the way Linux works: it renumbers the drives every time it

boots, so when one is dead or put offline, its position is "skipped";

BTW, BIOS (used by RPM, GRUB/LILO, NTLDR etc.) and Windows NT kernel do

the same; I think I read some xxxBSD does not, but I am unsure.



> 2) when I replace the 2nd harddrive with a new one, how

> exactly will RPM see it?



(Probably) as an unpartitionned one ("probably" because it is always

possible that the drive were partitionned, either at the mfg plant or in

another computer where it was used earlier.)



If you attach it to the same SATA channel as the dead one, it should

show up as "Hard disk 2."



> Isn't there any risk of mixing drives/partition tables?



There is always a risk; but not any risk specific to this task.



> Even if there are drives which are the same model (as the one

> replaced or the existing ones).



Well, you aill have to adjust the size of the volumes to fit the size of

the disk; usually, if the replaced drive is of the "same" size (here

.5TB), you will adjust the cylinder of the end of last partition (the

one in the 60,000 range); note it may appears twice if you are using

extended partitions, one for the container (of type 0F) and one for the

very last logical partition.



> How exactly is RPM information stored?



There are two places:

- one is the standard place, the partition table which is stored as part

of the first sector on disk (the MBR.) This place is common to any other

tool and any operating system, it is the MBR standard way to partition a

disk (there exist other standards like GPT, but RPM does not support

them.)

- the other is optional and specific to RPM 2.4x, it is the VTOC used to

store the 32 volumes you can create on each disk; you should use RPM

beta version 2.42/43/44, _and_ you should have created a type F0

partition. The volumes stored there are not visible to any other tool or

operating system, unless you also put an entry in the MBR (the digit 1

to 4 in the 2nd column.)

Again, this function is entirely optionnal, and it is very likely you

are not using it (particularly on a 2nd drive...)



> Does each HDD only has information about itself?



Yes.



> Or can a HDD have the information

> (stored in the RPM partition) about all the drives in the system?



Not usually.

It was perhaps a function of earlier version (<2.38), but AFAIK it was

not carried over (implemented) to the 2.4x line. I think the structure

on disk could be able to store the information, but the boot manager

code is not able to either put values or get them while booting.



> I was thinking on removing RPM from all HDDs except the first

> one (so that no automatic fixing happens in these drives).

> Does this only require removing the boot loader and deleting

> the RPM partition. Maybe I only need to remove the boot loader?



First, removing the bootloader (the code part of the MBR) on any drive

beside the first one in the system has NO effect, UNTIL a disk fails.

Then, if you wiped the bootloader of a surviving disk, you are not able

to boot...

In other words: the bootloader on the 2nd disk is only there for

disaster recovery reasons.



Then, removing the F0 partition from the 2nd etc. drives have two

possible effects:

- if you are booting directly to a volume on the 2nd drive _and_ the

volume is not present in the MBR, only in RPM's VTOC (which is stored

inside this partition), removing this partition prevents such boot to

occur: chances are high you are not using this feature.

- if your 1st drive dies, and if you kept the RPM bootloader on the

second disk, you'll get the possibility to enter RPM at boot. This

might, or might not, be a good thing for you, it all depends opn your

recovery plan.



Antoine




















_________________________________________________________________
http://redirect.gimas.net/?n=M0908axFotos2
-> Für Fotos hier abdrücken <-

[Non-text portions of this message have been removed]