On Tue, 2004-09-14 at 13:07, Res03q8w@gte.net wrote:
> Robin if something happened to my client information harddrive which is
> ReiserFS the first thing I would not be doing is trying to recover it my
> self. I will blow the 1k-5k on Drivesavers If they can recover the data
> from laptop hd that was flatten by a semi they will recover what ever i need
> off of that. While 100% percent recovery is not promised they have there
> recovery average in the high 90s
> but that is just me....
I think Robin was referring to the case where you have only a few
sectors go bad. The disc is not toast, but there are unrecoverable
blocks as a result. So the filesystem can be brought to a consistent
state and used as normal.
I have had this happen on several Ext2, Ext3 and ReiserFS filesystems.
I have not had it happen on an XFS system, because I've yet to deploy
XFS on something that did not have an intelligent RAID controller** (And
I don't use cheap "FRAID" cards**).
In the case of Ext2 and Ext3, dropping down to a full fsck -y on both,
the filesystems could be made consistent. Several inodes had blocks
that were made unrecoverable, they were reported as such, and moved to
the lost+found directory.
In the case of ReiserFS, in each and every case, the fsck toasted the
filesystem utterly. If I attempted the procedure, I was smart enough to
dd the filesystem first. In the case of others who ran it without me
being there, they toasted it with no turning back.
-- Bryan
**NOTE: For example, 3Ware Escalade cards reserve blocks on ATA discs
and do sector remapping automatically (assuming RAID-1, RAID-0+1 or
RAID-5, where there is a copy/parity of the sector lost). "FRAID" cards
typically do not offer this, and do it in 100% software if they do.
Standalone ATA discs do not offer remapping, so it is up to the OS to
mark blocks bad. SCSI can do sector remapping inherently, but unless it
is RAID with a copy/parity, automatic recovery of data is not certain.
In any case, unless you have an intelligent RAID card, it's up to the OS
to recover or at least make the filesystem consistent when unrecoverable
sector errors occur. This is typically done off-line (not mounted).
--
Linux Enthusiasts call me anti-Linux.
Windows Enthusisats call me anti-Microsoft.
They both must be correct because I have over a
decade of experience with both in mission critical
environments, resulting in a bigotry dedicated to
mitigating risk and focusing on technologies ...
not products or vendors
--------------------------------------------------
Bryan J. Smith, E.I. b.j.smith at ieee.org
-----------------------------------------------------------------------
This list is provided as an unmoderated internet service by Networked
Knowledge Systems (NKS). Views and opinions expressed in messages
posted are those of the author and do not necessarily reflect the
official policy or position of NKS or any of its employees.
This archive was generated by hypermail 2.1.3 : Fri Aug 01 2014 - 17:37:44 EDT