disparty - another RAID4 tool - AVS Forum
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post #1 of 28 Old 10-15-2012, 01:18 PM - Thread Starter
 
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OK, in my search for RAID4 parity based protection utilities, I stumbled upon disparity. It is like SnapRAID, only simple enough that I can understand its command line. It is also still actively being worked on (albeit after a long pause). The next version will contain its own GUI, but for now you can either download the utility itself here:

http://www.vilett.com/disParity/forum/topic.php?id=94


Or download the GUI which also has the utility built in here:

http://student.fau.edu/pbryan/web/dsm/



I am going to remove SnapRAID and test this one out. Anyone currently using disparity?
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post #2 of 28 Old 10-15-2012, 06:41 PM
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I looked past disParity due to it not having dual parity drives.
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post #3 of 28 Old 10-15-2012, 08:56 PM - Thread Starter
 
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Out of curiosity, what does dual parity drives gain you?

EDIT: If you use the DisParity Storage Manager (the GUI), you can have more than one parity drive:
Quote:
With DisParity Storage Manager, you can have multiple parity volumes,
http://student.fau.edu/pbryan/web/dsm/
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post #4 of 28 Old 10-16-2012, 09:47 AM - Thread Starter
 
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Does no one use this?
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post #5 of 28 Old 10-16-2012, 11:31 AM
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Not many do. It might be the greatest thing in the world but if it hasn't gained a lot of traction then people are naturally going to shy away from it. I haven't checked it out in a long time, but I seem to remember that it didn't offer drive pooling so it wasnt much use compared to solutions that had a large community and offered pooling. Even compared to SnapRAID, I don't know if it has very many users.

Plus considering that the development on it stopped for some time, I don't know if I would trust it with my data.
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post #6 of 28 Old 10-16-2012, 02:30 PM - Thread Starter
 
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Development has restarted...though I have to say I newly discoverd the software. I like its easy to understand syntax, for example:

How to update the backup:

1. Open a command prompt, cd to the directory where you installed disParity,
and type "disparity update". Any files deleted since the last snapshot or
update will be removed from the parity. Any new files added since the last
snapshot or update will be added to the parity. Edited files will also
be updated.

How to recover a lost drive:

1. Open a command prompt, cd to the directory where you installed disParity,
and type "disparity recover [num] [dir]" from the command line. [num] is
the drive number to recover. [dir] is the location where you want the
recovered files to be written. This location must have enough space to
store the recovered data, or else disParity will eventually run out of disk
space and abort. An example might be "disparity recover 2 C:\data\" which
will restore whatever files were on drive #2 to the folder C:\data.
2. Check the log file and make sure that disParity reported "Hash verified" for
all of your recovered files.


How easy is that?
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post #7 of 28 Old 10-16-2012, 07:19 PM
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Quote:
Originally Posted by cybrsage View Post

Out of curiosity, what does dual parity drives gain you?
EDIT: If you use the DisParity Storage Manager (the GUI), you can have more than one parity drive:
http://student.fau.edu/pbryan/web/dsm/

Well that is new. I guess this page needs to be updated (http://snapraid.sourceforge.net/compare.html)
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post #8 of 28 Old 10-16-2012, 08:43 PM - Thread Starter
 
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AFAIK, it only works via the third party GUI (to use two parity drives). A new version with a built in GUI will be coming out in a few months - it is currently being worked on.
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post #9 of 28 Old 12-07-2012, 11:11 AM - Thread Starter
 
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A new version of disparity is in beta and it is MUCH nicer. It now has a built in GUI. If you want to try it out, go here:

http://www.vilett.com/disParity/forum/topic.php?id=156

I ran into an issue after the install, since I am upgrading from a previous version - I had to reboot after the install but the procedures did not mention that. I would reboot after install regardless, just to be sure. So far, I like the changes.
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post #10 of 28 Old 12-09-2012, 09:15 PM - Thread Starter
 
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DisParity is now on beta 0.28.

http://www.vilett.com/disParity/beta.html
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post #11 of 28 Old 12-23-2012, 09:56 PM - Thread Starter
 
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Beta 0.29 has been released.

http://www.vilett.com/disParity/beta.html

If you have never tried disparity, you should. If you tried it in the past, it is a VERY VERY VERY different animal now - you should try it again.
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post #12 of 28 Old 12-24-2012, 12:18 PM
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Is it still limited to a single parity drive?
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post #13 of 28 Old 12-25-2012, 06:59 AM - Thread Starter
 
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Dunno, I only own one 3TB drive I am willing to toss aside for use as the parity drive. Why do you want multiple parity drives?
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post #14 of 28 Old 12-25-2012, 08:17 AM
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some would want more once they go past 8 or 10 dru drives.

note: the post above is my opinion. as such, when reading any recommendations from me, please do you research and seek out other recommendations and make up your own mind on your next course of action. i mean, most reasonable adults should know that, but it seems this should be stated anyways.
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post #15 of 28 Old 12-25-2012, 04:20 PM
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Quote:
Originally Posted by cybrsage View Post

Why do you want multiple parity drives?

For greater protection against data loss. It is even more helpful with snapshot RAID (as compared to realtime RAID) since it is possible to delete files and then have a drive failure before a sync.
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post #16 of 28 Old 12-26-2012, 06:57 AM - Thread Starter
 
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AFAIK, disparity does not do realtime raid (at least if it does I have not seen it) and only does snapshot raid. So basically, you are saying you guys use two parity drives in case one parity drive fails at the same time a data drive fails. Is that correct? Wouldn't running a batch file to copy the changed files do the same thing? Something like:

@echo off
REM Copy parity files
@echo Copying Parity Files to Secondary Drive
xcopy Z:\*.* Y:\*.* /e /c /r /y
@echo Copy Complete
pause
exit

With Z being your primary parity drive and Y being your secondary parity drive, and running the batch file after the sync is complete. I have never seen the need for two parity drives, but that does not mean others do not. Just curious is all.
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post #17 of 28 Old 12-26-2012, 07:01 AM - Thread Starter
 
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Beta .30 has been released:

http://www.vilett.com/disParity/beta.html

This one adds the ability to restore individually deleted files, provided you have not run the sync since then.
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post #18 of 28 Old 12-26-2012, 11:31 AM
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Quote:
Originally Posted by cybrsage View Post

AFAIK, disparity does not do snapshot raid (at least if it does I have not seen it).

Are you claiming disparity does realtime RAID?
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post #19 of 28 Old 12-26-2012, 01:52 PM - Thread Starter
 
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Quote:
Originally Posted by jim2100 View Post

Are you claiming disparity does realtime RAID?

Oops, wrote that backwards. It DOES do snapshot, not realtime. My bad, I will edit the previous post.

I do not understand how having two parity drives will help you if you change something and then lose a drive prior to the sync. Why would two parity drives help you in that instance? It would appear that neither one would be updated if you did not yet sync.
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post #20 of 28 Old 12-26-2012, 04:30 PM
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I'm not going to explain the whole theory of operation of snapshot RAID (if you need that, you can probably find it with enough googling). I'll just give a quick example (assuming SnapRAID, since that is what I am most familiar with).

You have 8 data drives (#1-#8) and 2 parity drives. You run a sync. Then you change (i.e., overwrite) some files on #1. Then #2 fails. You should be able to fully recover all of the data from #2. SnapRAID will notice that some of the checksums on #1 don't match (the data you changed), but it will be able to use dual parity to fill in the holes, just as if two drives had failed.

Note that if you only had one parity drive, you would be unable to recover some amount of data on #2, roughly equal in size to the amount of data that was changed on #1.
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post #21 of 28 Old 12-26-2012, 09:51 PM - Thread Starter
 
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I am a bit confused still. Is the 1 and 2 the two parity drives or two of the data drives?

Wouldn't the parity info on the two parity drives be the exact same info? Why would having two copies of the same thing be of any help?

From what I can tell of disParity (maybe I should ask the author, eh?), it appears it knows what is on each drive, that it does not lump them all together. When I run a scan, it tells me the differences for each data drive and then it updates based on that one data drive based on the individual files. When I remove a data drive from the set, it goes through and deletes the parity based on the protected files. Since I have mostly ISO's of BluRays, the files are quite large. This means I can watch it as it runs. It tells me the number of adds, changes, and deletes since the last run, per data drive. When I say to update, it creates the parity info while scanning each file (it lists the file it is currently working upon). When you remove the drive, it does the same thing in reverse.

I will read up more on RAID4 Parity and how it works, it is quite possible I just do not understand.
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post #22 of 28 Old 01-10-2013, 06:35 AM - Thread Starter
 
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DisParity has been updated again. One of the things added (has been there for a few revs and I did not notice) is that you can recover individual files now...called Undelete by the program. You can decide where to put them too, you do not have to recover them to the drive they originated on. Current rev is:

Beta 0.34 is up and running. http://www.vilett.com/disParity/beta.html
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post #23 of 28 Old 01-18-2013, 02:05 PM - Thread Starter
 
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Disparity is up to beta 0.35 now:

Changes in version 0.35 beta released Monday, January 14, 2013
•Fixed bug where errors accessing the root of a drive during a scan were not reported in the UI.
•A warning is now displayed when trying to set the temp folder to a location on the parity drive.
•Scanning of the parity folder itself is now prevented.
•The log file now lists the time to completion for long running tasks like update and verify.
•Fixed a sporadic crash bug in Reset.


http://www.vilett.com/disParity/beta.html
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post #24 of 28 Old 04-03-2013, 10:15 PM
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Checked out the tool for the first time seams to a nice looking tool. and its up to disParity 0.38 now.
http://www.vilett.com/disParity/beta.html

Has anyone been using the tool long enough to comment on it?
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post #25 of 28 Old 04-04-2013, 10:43 AM
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I am going to check it out when I build new server to replace Win2K Server.

I am thinking of throwing all of my old PATA drives into a box and making a huge array with 1 large Parity drive. i.e. 15-20x <500Gb drives, and 1x 2-3 Tb parity drive.

Is that feasable?

6 TV's in the house on FiOS and we only pay $4.99/month to connect them all!!! Power to the CableCard and WMC7!!!
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post #26 of 28 Old 04-04-2013, 11:03 AM
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Quote:
Originally Posted by cybrsage View Post

Wouldn't the parity info on the two parity drives be the exact same info? Why would having two copies of the same thing be of any help?

2 parity drives allows for up to 2 drive failures without data loss. The 2 parity drives hold different data. In the world of SnapRaid, they call it the P and the Q parity drives.
For an explanation on the concept, read on the differences between RAID5 and RAID6...
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post #27 of 28 Old 04-04-2013, 05:00 PM - Thread Starter
 
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Originally Posted by RudyRedNose View Post

2 parity drives allows for up to 2 drive failures without data loss. The 2 parity drives hold different data. In the world of SnapRaid, they call it the P and the Q parity drives.
For an explanation on the concept, read on the differences between RAID5 and RAID6...

AH, ok, I understand what you are saying. I can see some people wanting that, I personally do not want to lose two 4TB drives to parity alone.
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post #28 of 28 Old 04-04-2013, 05:02 PM - Thread Starter
 
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Originally Posted by im bored View Post

Checked out the tool for the first time seams to a nice looking tool. and its up to disParity 0.38 now.
http://www.vilett.com/disParity/beta.html

Has anyone been using the tool long enough to comment on it?

I have been using it quite some time now, it works well. You can recover and entire drive or undelete some or all of the files you deleted between now and your last sync job.
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