badblocks handling with LVM
I have blocks marked bad on a ext2 filesystem.
The device has bad blocks.
I'm wondering how bad blocks are handled with lvm.
I would like to create a phycal volume on this device and use reiserfs on it.
Could you give me some informations ?
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Laurent
Quoted 4 lines · Laurent
I have blocks marked bad on a ext2 filesystem. The device has bad blocks. I'm wondering how bad blocks are handled with lvm. I would like to create a phycal volume on this device and use reiserfs on it.
Could you give me some informations ?
As long as the bad blocks are not in the first ~250kB of the partition/disk then LVM doesn't care about it. However, reiserfs doesn't yet support bad blocks in the filesystem (this is currently under development AFAIK), so this will not help you.
Cheers, Andreas
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Andreas Dilger \ "If a man ate a pound of pasta and a pound of antipasto,
\ would they cancel out, leaving him still hungry?"
http://www-mddsp.enel.ucalgary.ca/People/adilger/ -- DogbertQuoted 10 lines · Andreas Dilger
Quoted 4 lines · Laurent
I have blocks marked bad on a ext2 filesystem. The device has bad blocks. I'm wondering how bad blocks are handled with lvm. I would like to create a phycal volume on this device and use reiserfs on it. Could you give me some informations ?
As long as the bad blocks are not in the first ~250kB of the partition/disk then LVM doesn't care about it. However, reiserfs doesn't yet support bad blocks in the filesystem (this is currently under development AFAIK), so this will not help you.
The problem is that when you move LV's around and make snapshots the bad blocks on the underlieing media will move. Therefore I think that management of bad blocks possibly should be done in the LVM.
Or should we just assume that LVM runs over RAID arrays of ATA/SCSI disks that have sector-sparing so that bad blocks are not an issue?
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http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/ Postal SMTP/POP benchmark http://www.coker.com.au/projects.html Projects I am working on http://www.coker.com.au/~russell/ My home page
Quoted 12 lines · Russell Coker
Quoted 10 lines · Andreas Dilger
Quoted 4 lines · Laurent
I have blocks marked bad on a ext2 filesystem. The device has bad blocks. I'm wondering how bad blocks are handled with lvm. I would like to create a phycal volume on this device and use reiserfs on it. Could you give me some informations ?
As long as the bad blocks are not in the first ~250kB of the partition/disk then LVM doesn't care about it. However, reiserfs doesn't yet support bad blocks in the filesystem (this is currently under development AFAIK), so this will not help you.
Quoted 6 lines
The problem is that when you move LV's around and make snapshots the bad blocks on the underlieing media will move. Therefore I think that management of bad blocks possibly should be done in the LVM.
Or should we just assume that LVM runs over RAID arrays of ATA/SCSI disks that have sector-sparing so that bad blocks are not an issue?
That's what I recommend because disks typically "hide" bad sectors to a certain degree using bad block relocation et al.
If the given disk capacity for this is not enough because too many bad blocks occured already then you are in serious trouble and need to repleace your disk (subsystem) anyway IMO.
Quoted 10 lines
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-- http://www.coker.com.au/bonnie++/ Bonnie++ hard drive benchmark http://www.coker.com.au/postal/ Postal SMTP/POP benchmark http://www.coker.com.au/projects.html Projects I am working on http://www.coker.com.au/~russell/ My home page _______________________________________________ linux-lvm mailing list [email protected] http://lists.sistina.com/mailman/listinfo/linux-lvm
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Regards,
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
[email protected] +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-Quoted 4 lines · Heinz J. Mauelshagen
Quoted 4 lines
The problem is that when you move LV's around and make snapshots the bad blocks on the underlieing media will move. Therefore I think that management of bad blocks possibly should be done in the LVM.
Quoted 8 lines
Quoted 2 lines
Or should we just assume that LVM runs over RAID arrays of ATA/SCSI disks that have sector-sparing so that bad blocks are not an issue?
That's what I recommend because disks typically "hide" bad sectors to a certain degree using bad block relocation et al.
If the given disk capacity for this is not enough because too many bad blocks occured already then you are in serious trouble and need to repleace your disk (subsystem) anyway IMO.
And if anyone insist on using LVM to mark the blocks anyway, it can be done with out special code. Just create a volume named "broken", and put the PVs in question in this.
Signature · 2 lines
Ragnar Kj�rstad Big Storage
Quoted 3 lines · Ragnar Kjørstad
And if anyone insist on using LVM to mark the blocks anyway, it can be done with out special code. Just create a volume named "broken", and put the PVs in question in this.
That would be a waste of space, my PVs are all 10+GB in size, I'd like bad block handling on PE level not on PV level.
But I can live with out badblock handling in LVM.
Cu,
Goetz.
Quoted 7 lines · Goetz Bock
Quoted 3 lines · Ragnar Kj�rstad
And if anyone insist on using LVM to mark the blocks anyway, it can be done with out special code. Just create a volume named "broken", and put the PVs in question in this.
That would be a waste of space, my PVs are all 10+GB in size, I'd like bad block handling on PE level not on PV level.
But I can live with out badblock handling in LVM.
Sorry, I meant "put the PEs in question in this".
(it doesn't actually do anything, just mark that space as used, so you won't accidently put something else there)
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Ragnar Kj�rstad Big Storage
Quoted 14 lines · Ragnar Kj�rstad
Quoted 4 lines · Heinz J. Mauelshagen
Quoted 4 lines
The problem is that when you move LV's around and make snapshots the bad blocks on the underlieing media will move. Therefore I think that management of bad blocks possibly should be done in the LVM.
Quoted 8 lines
Quoted 2 lines
Or should we just assume that LVM runs over RAID arrays of ATA/SCSI disks that have sector-sparing so that bad blocks are not an issue?
That's what I recommend because disks typically "hide" bad sectors to a certain degree using bad block relocation et al.
If the given disk capacity for this is not enough because too many bad blocks occured already then you are in serious trouble and need to repleace your disk (subsystem) anyway IMO.
Quoted 3 lines
And if anyone insist on using LVM to mark the blocks anyway, it can be done with out special code. Just create a volume named "broken", and put the PVs in question in this.
It is not that I really *insist*.
I just say that it doesn't make a whole lot of sense today, because most of the disk (subsystems) don't expose bad blacks any longer.
Once those start too, they are ready to go to the trashcan IMO anyway.
Quoted 9 lines
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-- Ragnar Kj�rstad Big Storage _______________________________________________ linux-lvm mailing list [email protected] http://lists.sistina.com/mailman/listinfo/linux-lvm
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Regards,
Heinz -- The LVM Guy --
*** Software bugs are stupid.
Nevertheless it needs not so stupid people to solve them ***
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-
Heinz Mauelshagen Sistina Software Inc.
Senior Consultant/Developer Am Sonnenhang 11
56242 Marienrachdorf
Germany
[email protected] +49 2626 141200
FAX 924446
=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-=-Quoted 9 lines · Russel Coker
Quoted 4 lines · Andreas Dilger
As long as the bad blocks are not in the first ~250kB of the partition/disk then LVM doesn't care about it. However, reiserfs doesn't yet support bad blocks in the filesystem (this is currently under development AFAIK), so this will not help you.
The problem is that when you move LV's around and make snapshots the bad blocks on the underlieing media will move. Therefore I think that management of bad blocks possibly should be done in the LVM.
As long as the LVM metadata and the snapshotted blocks themselves don't hit more bad blocks, the snapshot itself will be fine. ext2 just allocates all of the bad blocks to a file, and presumably this file gets no I/O, so just doing a snapshot of a filesystem with bad blocks is not an issue.
This leaves several other alternatives:
- New LV has bad blocks: no different than bad blocks in a partition, so a new ext2 filesystem can handle this via badblocks(8).
- Extended LV has bad blocks in added PEs: you can run badblocks(8) on the newly allocated part of the LV (specify a start block) before fs extend (can't use e2fsadm in this case).
- pvmove a filesystem to PEs with bad blocks: you are mostly screwed. If you _really_ wanted, you could run badblocks on the PEs (added to a temp LV), keep a list of bad blocks, add them to the ext2 filesystem (with appropriate math for their new offset inside the LV, etc) before the PE is moved, but it is very ugly. As someone else suggested, you could simply add the entire PE to "lvbad", and simply not use them. If you have so many PEs with bad sectors that it uses up a large part of your device, it is time to get a new disk (or use RAID with 2 semi-bad disks and hope that they don't have 2 bad sectors in the same place).
Cheers, Andreas
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Andreas Dilger TurboLabs filesystem development http://sourceforge.net/projects/ext2resize/ http://www-mddsp.enel.ucalgary.ca/People/adilger/