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Old 03-04-2010, 06:26 AM
Timo Schoeler
 
Default Recover RAID

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thus Jeff Sadino spake:
> Thanks Timo, that one actually made me laugh!

I really hope that this wasn't irony from your side. Well, if there's
nothing left, there's still gallows humor...

Timo

> On Wed, Mar 3, 2010 at 9:15 PM, Timo Schoeler
> <timo.schoeler@riscworks.net>wrote:
>
> thus Sorin Srbu spake:
>>>> From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On
> Behalf
>>>> Of Jeff Sadino
>>>> Sent: Thursday, March 04, 2010 6:15 AM
>>>> To: CentOS mailing list
>>>> Subject: Re: [CentOS] Recover RAID
>>>>
>>>> Backups? I wish I will now.
>>>> But looking closer, that md1 is not my OS partition, just a data
> partition.
>>>> If I take that md1 entry out of the raidtab file and restart the
> computer, I
>>>> would think that it would start up just fine, minus the data partition
> (and
>>>> for the moment neglecting any vital programs that might be installed on
> that
>>>> partition). My question is when I start the computer back up, in order
> to
>>>> start up without that partition there any more, will the OS write any new
>>>> files or anything that will not be reversible?
>>>> ----
>>>>
>>>> Eh? Raid0 with no backups? For real?
> Backups are for sissies; running a hara-kiri RAID demands *not* having
> backups. Or did the kamikaze pilots have parachutes?
>
> SCNR
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Old 03-04-2010, 06:39 AM
"Sorin Srbu"
 
Default Recover RAID

>-----Original Message-----
>From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On
Behalf
>Of Timo Schoeler
>Sent: Thursday, March 04, 2010 8:15 AM
>To: CentOS mailing list
>Subject: Re: [CentOS] Recover RAID
>
>>> Backups? I wish I will now.
>>[...]
>> Eh? Raid0 with no backups? For real?
>
>Backups are for sissies; running a hara-kiri RAID demands *not* having
>backups. Or did the kamikaze pilots have parachutes?

8-)

Or as Linus Torvalds is said to have said; "Real men don't use backups, they
post their stuff on a public ftp server and let the rest of the world make
copies."

;-)
--
/Sorin
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Old 03-06-2010, 03:07 AM
Jeff Sadino
 
Default Recover RAID

I have access to all of the HEX data on each drive, and I now which sector each stripe starts at.* Is there any way that I can reconstruct my data from that?* When a file gets split up in RAID0, does the controller use the same sectors on each stripe to write the file parts?



Thanks,
Jeff

On Wed, Mar 3, 2010 at 9:39 PM, Sorin Srbu <sorin.srbu@orgfarm.uu.se> wrote:


>-----Original Message-----

>From: centos-bounces@centos.org [mailto:centos-bounces@centos.org] On

Behalf

>Of Timo Schoeler

>Sent: Thursday, March 04, 2010 8:15 AM

>To: CentOS mailing list

>Subject: Re: [CentOS] Recover RAID

>

>>> Backups? *I wish *I will now.

>>[...]

>> Eh? Raid0 with no backups? For real?

>

>Backups are for sissies; running a hara-kiri RAID demands *not* having

>backups. Or did the kamikaze pilots have parachutes?



8-)



Or as Linus Torvalds is said to have said; "Real men don't use backups, they

post their stuff on a public ftp server and let the rest of the world make

copies."



;-)

--

/Sorin


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Old 03-06-2010, 03:18 AM
John R Pierce
 
Default Recover RAID

Jeff Sadino wrote:
> I have access to all of the HEX data on each drive, and I now which
> sector each stripe starts at. Is there any way that I can reconstruct
> my data from that? When a file gets split up in RAID0, does the
> controller use the same sectors on each stripe to write the file parts?

if a raid0 has a stripe size of 32k, then every other 32k is written on
one drive, and every other 32k is written on the next drive.

if you lose one drive, then every other 32k of your file system is wiped
out, gone, kaput. its like taking a 12-gauge shotgun to your data
and directory information.




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Old 03-06-2010, 03:22 AM
Jeff Sadino
 
Default Recover RAID

Thank you John.* The thing is my data was not overwritten, corrupted, etc.* Some was, but I know which parts.* Basically, I just cleared the file system designation.* So if a file is 64K, does the first 32K on drive 1 contain the first half of the file and the first 32K on drive 2 contain the second half, or are the 32 size chunks on random locations?



Thanks,
Jeff

On Fri, Mar 5, 2010 at 6:18 PM, John R Pierce <pierce@hogranch.com> wrote:


Jeff Sadino wrote:

> I have access to all of the HEX data on each drive, and I now which

> sector each stripe starts at. *Is there any way that I can reconstruct

> my data from that? *When a file gets split up in RAID0, does the

> controller use the same sectors on each stripe to write the file parts?



if a raid0 has a stripe size of 32k, then every other 32k is written on

one drive, and every other 32k is written on the next drive.



if you lose one drive, then every other 32k of your file system is wiped

out, gone, kaput. * * *its like taking a 12-gauge shotgun to your data

and directory information.









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Old 03-06-2010, 03:36 AM
Ross Walker
 
Default Recover RAID

On Mar 5, 2010, at 11:22 PM, Jeff Sadino <jsadino.queens@gmail.com>
wrote:

> Thank you John. The thing is my data was not overwritten,
> corrupted, etc. Some was, but I know which parts. Basically, I
> just cleared the file system designation. So if a file is 64K, does
> the first 32K on drive 1 contain the first half of the file and the
> first 32K on drive 2 contain the second half, or are the 32 size
> chunks on random locations?

Trying to restich a broken RAID0 is going to be difficult. Question is
is the md raid metadata ok, if it isn't then you are hosed. Make sure
the metadata, usually stored in the last 64k+ of the partition is ok
then see if you can reassemble the array, then try using a disk or
file system rescue utility on a copy of the md raid block device and
see what data you can recover.

-Ross

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Old 03-06-2010, 03:45 AM
Ross Walker
 
Default Recover RAID

On Mar 5, 2010, at 11:36 PM, Ross Walker <rswwalker@gmail.com> wrote:

> On Mar 5, 2010, at 11:22 PM, Jeff Sadino <jsadino.queens@gmail.com>
> wrote:
>
>> Thank you John. The thing is my data was not overwritten,
>> corrupted, etc. Some was, but I know which parts. Basically, I
>> just cleared the file system designation. So if a file is 64K,
>> does the first 32K on drive 1 contain the first half of the file
>> and the first 32K on drive 2 contain the second half, or are the 32
>> size chunks on random locations?
>
> Trying to restich a broken RAID0 is going to be difficult. Question
> is is the md raid metadata ok, if it isn't then you are hosed. Make
> sure the metadata, usually stored in the last 64k+ of the partition
> is ok then see if you can reassemble the array, then try using a
> disk or file system rescue utility on a copy of the md raid block
> device and see what data you can recover.

Let me expand by saying.

1 make sure the partition table is restored to it's exact prior setup.

2 verify the md raid metadata at the end of the raid partition is ok.
Need to research that one.

3 reassemble the raid0

4 make a copy of the raid device

5 use recovery tools on the copy to retrieve as much data as you can

-Ross

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Old 03-06-2010, 04:26 AM
John R Pierce
 
Default Recover RAID

Jeff Sadino wrote:
> Thank you John. The thing is my data was not overwritten, corrupted,
> etc. Some was, but I know which parts. Basically, I just cleared the
> file system designation. So if a file is 64K, does the first 32K on
> drive 1 contain the first half of the file and the first 32K on drive
> 2 contain the second half, or are the 32 size chunks on random locations?

didn't you say you did a mkfs ext3 over this stripe's partition? that
would have overwirtten all the root directory areas, made a total mess
of things.

ifyou -just- used a fdisk program to change the partition type, quick,
change it back to what it was, and put it all back.


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Old 03-08-2010, 10:10 PM
Jeff Sadino
 
Default Recover RAID

Hello Everyone,

Thanks to everyone who helped me to learn about RAIDs, starting at the end and working backwards

I brought my system back up, minus the raid0 partition that was corrupted.* My question now is what's the best way to back up my server?* Basically, I have one more (software?) raid1 array, a cluster setup on 5 subnodes (but I don't see any of their data here, so prob just all scratch and OS space), and then a hardware RAID controller (10.54.1.100) attached to 2 raid setups (scratch, apps, and data as one setup and then last week we added the shacks as a seperate 12TB array.* It came as a RAID, but I think we had to decouple it b/c our OS couldn't read it), and then we have the computer with mounts referencing our main Windows server (10.1.1.17), which is backed up by our Windows guy.


Should I use the empty shacks as backup space?

I hope that all makes sense.* If not, please let me know.* I really want to back up and ensure thsi never happens again.* Thank you!

This is the output from `df -h`:


Filesystem**************************************** *** Size* Used Avail Use% Mounted on
/dev/sda1*********** * * * * * * * * * * * * * * * * ** 9.8G* 7.5G* 2.3G* 77% /
none********************************************** ****** 4.0G**** 0* 4.0G** 0% /dev/shm


/dev/md0********************************************* 459G* 140G* 296G* 33% /export
/dev/sda2******************************************* 2.0G* 1.4G* 561M* 72% /var
tmpfs********************************************* ***** 241M* 3.8M* 238M** 2% /var/lib/ganglia/rrds


10.54.1.100:/mnt/RAID/FSDATA**** 1.1T* 812G* 223G* 79% /data
10.54.1.100:/mnt/RAID/apps************ 1.1T* 812G* 223G* 79% /apps
10.54.1.100:/scratch************************** 72G** 13G** 55G* 19% /scratch
10.54.1.100:/mnt/shack1******************* 2.0T* 103M* 1.9T** 1% /mnt/shack1


10.54.1.100:/mnt/shack2******************* 1.8T* 238G* 1.5T* 14% /mnt/fs3
10.54.1.100:/mnt/shack3******************* 1.8T* 285G* 1.5T* 17% /mnt/fs4
10.54.1.100:/mnt/shack4******************* 1.8T* 100M* 1.7T** 1% /mnt/shack4


10.54.1.100:/mnt/shack5******************* 1.8T* 100M* 1.7T** 1% /mnt/shack5
10.54.1.100:/mnt/shack6******************* 1.7T* 101M* 1.6T** 1% /mnt/shack6
//10.1.1.17/Scanner_data2**************** 11T* 4.7T* 5.4T* 47% /mnt/scanner_data2


//10.1.1.17/SCANNER_DATA********** 11T* 4.7T* 5.4T* 47% /mnt/scanner_data
//10.1.1.17/shared****************************** 11T* 4.7T* 5.4T* 47% /mnt/shared


//10.1.1.17/fMRI**** * * * * * * * * * * * * * * * 11T* 4.7T* 5.4T* 47% /mnt/fMRI
//10.1.1.17/USERS**** * * * * * * * * * * * * 11T* 4.7T* 5.4T* 47% /mnt/users


/export/home/fs431*************************** 459G* 140G* 296G* 33% /home/fs431
/export/home/coreg** * * * * * * * * * * * * 459G* 140G* 296G* 33% /home/coreg

On Fri, Mar 5, 2010 at 7:26 PM, John R Pierce <pierce@hogranch.com> wrote:


Jeff Sadino wrote:

> Thank you John. *The thing is my data was not overwritten, corrupted,

> etc. *Some was, but I know which parts. *Basically, I just cleared the

> file system designation. *So if a file is 64K, does the first 32K on

> drive 1 contain the first half of the file and the first 32K on drive

> 2 contain the second half, or are the 32 size chunks on random locations?



didn't you say you did a mkfs ext3 over this stripe's partition? * that

would have overwirtten all the root directory areas, made a total mess

of things.



ifyou -just- used a fdisk program to change the partition type, quick,

change it back to what it was, and put it all back.





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http://lists.centos.org/mailman/listinfo/centos



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Old 03-08-2010, 11:16 PM
Christopher Chan
 
Default Recover RAID

On Tuesday, March 09, 2010 07:10 AM, Jeff Sadino wrote:
> Hello Everyone,
>
> Thanks to everyone who helped me to learn about RAIDs, starting at the
> end and working backwards
>
> I brought my system back up, minus the raid0 partition that was
> corrupted. My question now is what's the best way to back up my
> server? Basically, I have one more (software?) raid1 array, a cluster
> setup on 5 subnodes (but I don't see any of their data here, so prob
> just all scratch and OS space), and then a hardware RAID controller
> (10.54.1.100) attached to 2 raid setups (scratch, apps, and data as one
> setup and then last week we added the shacks as a seperate 12TB array.
> It came as a RAID, but I think we had to decouple it b/c our OS couldn't
> read it), and then we have the computer with mounts referencing our main
> Windows server (10.1.1.17), which is backed up by our Windows guy.
> Should I use the empty shacks as backup space?

/me in favour of multiple online 'backup' servers in separate locations.
Forget tape or whatever else backup.

Hardware for doing that is dirt cheap compared to tape libraries/drives.
But I use ZFS with snapshots for this purpose so if you want or need
incremental backups then you may have to look elsewhere...
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