The effects of multiple layers of block drivers
Hello,
I am starting to dig into the Block subsystem to try and uncover the reason for some data I lost recently. My situation is that I have multiple block drivers on top of each other and am wondering how the effectss of a raid 5 rebuild would affect the block devices above it.
The layers are raid 5 -> lvm -> cryptoloop. It seems that after the raid 5 device was rebuilt by adding in a new disk, that the cryptoloop doesn't have a valid ext3 partition on it.
As a raid device re-builds is there ant rearranging of sectors or corresponding blocks that would effect another block device on top of it?
Sincerely,
Dennison Williams
Quoted 6 lines · On Thursday January 10, [email protected] wrote:
Hello,
I am starting to dig into the Block subsystem to try and uncover the reason for some data I lost recently. My situation is that I have multiple block drivers on top of each other and am wondering how the effectss of a raid 5 rebuild would affect the block devices above it.
It should "just work" - no surprises. raid5 is just a block device like any other. When doing a rebuild it might be a bit slower, but that is all.
Quoted 4 lines
The layers are raid 5 -> lvm -> cryptoloop. It seems that after the raid 5 device was rebuilt by adding in a new disk, that the cryptoloop doesn't have a valid ext3 partition on it.
There was a difference of opinion between raid5 and dm-crypt which could cause some corruption.
What kernel version are you using, and are you using dm-crypt or loop (e..g losetup) with encryption?
Quoted 3 lines
As a raid device re-builds is there ant rearranging of sectors or corresponding blocks that would effect another block device on top of it?
No.
NeilBrown
----- Message from [email protected] ---------
Date: Thu, 10 Jan 2008 14:58:49 -0800
From: Dennison Williams <[email protected]>
Reply-To: Dennison Williams <[email protected]>
Subject: The effects of multiple layers of block drivers
To: [email protected]
Quoted 11 lines
Hello,
I am starting to dig into the Block subsystem to try and uncover the reason for some data I lost recently. My situation is that I have multiple block drivers on top of each other and am wondering how the effectss of a raid 5 rebuild would affect the block devices above it.
The layers are raid 5 -> lvm -> cryptoloop. It seems that after the raid 5 device was rebuilt by adding in a new disk, that the cryptoloop doesn't have a valid ext3 partition on it.
Quoted 5 lines
As a raid device re-builds is there ant rearranging of sectors or corresponding blocks that would effect another block device on top of it?
Sincerely,
Dennison Williams
----- End message from [email protected] -----
If you add a disk and do a reshape the layer on top of the raid5 should only notice that the device is larger now. But yes, there is a rearranging of sectors going on. However this is transparent to layers on top. Did you have a disk failure during the reshape? If yes you probably have been bitten by the same bug as me: (http://marc.info/?l=linux-raid&m=119910305111460&w=2).
Kind regards,
========================================================================
# _ __ _ __ http://www.nagilum.org/ \n icq://69646724 #
# / |/ /__ ____ _(_) /_ ____ _ [email protected] \n +491776461165 #
# / / _ / _ / / / // / ' \ Amiga (68k/PPC): AOS/NetBSD/Linux #
# /_/|_/\_,_/\_, /_/_/\_,_/_/_/_/ Mac (PPC): MacOS-X / NetBSD /Linux #
# /___/ x86: FreeBSD/Linux/Solaris/Win2k ARM9: EPOC EV6 #
========================================================================
----------------------------------------------------------------
cakebox.homeunix.net - all the machine one needs..