Author Topic: Quad 4TB RAID choice - which is best for me?  (Read 4292 times)

szimbler

  • Calf
  • *
  • Posts: 36
Quad 4TB RAID choice - which is best for me?
« on: December 30, 2009, 04:25:20 am »
   

My Buffalo 4TB Quad recently failed, taking a lot of my non-backed up data with it. There is supposed to be a certain amount of redundancy when a HD fails, but in this case the Raid info disappeared too and I didn't have the money to pay a data recovery specialist to try and get my data back.

 

I have a new 4TB Quad on the way from Buffalo, and I would like advice on which RAID setup to choose.

 

My main consideration is that if a drive fails AND the remaining quad HDs no longer have the RAID info (and so I can't rebuild the RAID even if a new drive is installed), I want to choose a RAID set-up that will allow me to mount the remaining drives in a caddy, attach them to a PC and recover the important data to another PC or external drive manually before I have to wipe all the drives and start from scratch (or send my Quad back for another replacement).

 

Last tine I chose RAID 5 and once the raid info was lost, there was no easy way to recover all my data manually.

 

I repeat,  I would like to choose a RAID structure that :

1. can cope with 1 drive failure and rebuild the raid when the new drive is inserted, and

2. will allow me to mount the drives in a caddy one at a time and manually access the data should there be some catastrophic failure of the Quad.

 

Your advice is appreciated.

 

Simon


davo

  • Really Big Bull
  • VIP
  • *
  • Posts: 5952
Re: Quad 4TB RAID choice - which is best for me?
« Reply #1 on: December 30, 2009, 04:50:38 am »
   

Just create a RAID5 and backup to an external USB disk.

PM me for TFTP / Boot Images / Recovery files  LSRecovery.exe file.

szimbler

  • Calf
  • *
  • Posts: 36
Re: Quad 4TB RAID choice - which is best for me?
« Reply #2 on: December 30, 2009, 10:21:48 am »
   

Thanks for the advice. However Raid 5 will not (as I understand it) allow me to access the inforation on the drives by installing them in a caddy or PC running Linux in case of catastrophic failure, will it?

 

My quad has just been delivered so some more detailed answers would be appreciated!:smileyhappy:


szimbler

  • Calf
  • *
  • Posts: 36
Re: Quad 4TB RAID choice - which is best for me?
« Reply #3 on: December 31, 2009, 08:17:08 am »
   

My quad has just been delivered so some more detailed answers would be appreciated!:smileyhappy:


tsammyc

  • Calf
  • *
  • Posts: 40
Re: Quad 4TB RAID choice - which is best for me?
« Reply #4 on: January 05, 2010, 03:34:36 am »
   

I would go with two Raid 1 arrays. You will have 2 shares. Each share is represented by 2 mirrored drives. If a drive fails, you have RAID protection in the mirrored drive. If the whole Quad fails, each drive is readable on Linux PC.

 

Other than having 2 shares, the downside is that you lose about 0.3GB compared to Raid 5. Your 4TB Quad is 2 mirrored shares of 1TB each rather than 1 share of 2.3TB


szimbler

  • Calf
  • *
  • Posts: 36
Re: Quad 4TB RAID choice - which is best for me?
« Reply #5 on: January 07, 2010, 08:31:01 am »
   

sounds like good advice, though I have already gone witht he default of Raid 5! If I convert now to Raid 1 am I right in thinking that I'll have to wipe all the drives and start from scratch? In other words, if I rebuild as Raid 1 do I lose the data I have already transferred unless I copy it off onto another drive?


davo

  • Really Big Bull
  • VIP
  • *
  • Posts: 5952
Re: Quad 4TB RAID choice - which is best for me?
« Reply #6 on: January 07, 2010, 11:05:59 am »
   

Yes, changing the raid from 5 to 1 will erase any data on it so transfer any data off the LS before doing so.

PM me for TFTP / Boot Images / Recovery files  LSRecovery.exe file.

DumbTechDude

  • Tatanka
  • **
  • Posts: 60
Re: Quad 4TB RAID choice - which is best for me?
« Reply #7 on: January 07, 2010, 03:17:52 pm »
   

RAID 3 and onwards employ data stripping with data redundancy stored on all the drives, which is why it is difficult to recovery data once the array goes down.  Unless the Buffalo Quad supports duplexing (2 seperate dedicated independent controllers) controlling the 2 drives, you will suffer also from a RAID 1 failure if the controller fails.  Remember, in a RAID array, drive failure IS NOT the only fault.  Controller and power supply failure can do that too.  If the controller starts going, it will start writing corrupt data and if the power supply starts going, the voltage levels may not be within specs to ensure data writing or reading consistency either!

 

Again, if one can prevent RAID failures completely, why are DRS (Data Recovery Specialists) run a booming business?

 

Imagine RAID 5 as a gigantic single disk drive.  If you want about 3Tb contagious storage, then your Quad provides that.  But remember that the MTBF (Mean Time Between Failure) of each individual drives are reduced by 1/4 of their lifespan, NOT their quoted lifespan.  For example, if a drive is rated for 100,000 hours and all 4 of them are identical, their true MTBF would be 25,000 hrs only.  Since they all go on together, this means that if one of your RAID drive fails, what stops it from another drive to fail at the same time?!?  RAID 1 failure do exist, which is why, the best solution for you is to purchase 2 individual 2TB external drives and then back your Quad up to them.  When the Quad fails to reboot after you replaced its failed drive, you still have those backups you can restore from.  From my experience dealing with these data failure issues, it is FASTER to recover from a RAID failure if you have either backups on external drive or better yet another Quad you can run with while the failed Quad gets serviced or replaced and then RSYNCed later on from the backup Quad.

 

Sorry to be the purveyor of bad news, but if you value your data much and you need RAID, this is what you will have to consider..

 

 


szimbler

  • Calf
  • *
  • Posts: 36
Re: Quad 4TB RAID choice - which is best for me?
« Reply #8 on: January 08, 2010, 03:28:46 am »
   

Hmm...your words have a ring of truth about them. It looks to me as if I havebought a Quad hoping it will give me greater stability, when in fact it may have caused me more headaches than I started with. A couple of cheaper NAS drives could have given me the redundancy I wanted and the safety net in case of failure. **bleep** it! Good money down the drain!

 

Thanks for your advice and I will act upon it. I'll find myself a cheap NAS to use as a target backup for the Quad (suggestions?), buy a smart UPS for the quad, and keep my fingers crossed!

 

Many thanks for the sound advice.


JoshC

  • Big Bull
  • *****
  • Posts: 1110
Re: Quad 4TB RAID choice - which is best for me?
« Reply #9 on: January 08, 2010, 06:56:08 am »

You can always use an external Hd to back up from the LS to the Quad........That is what the USB port is designed for.   RAID is a great solution for HD failure not anything else.  Please keep in mind that there is many, many more factors that go into a NAS.


DumbTechDude

  • Tatanka
  • **
  • Posts: 60
Re: Quad 4TB RAID choice - which is best for me?
« Reply #10 on: January 08, 2010, 08:52:20 am »
   

First, buy a good UPS for your Quad or any NAS.  That's a must..  You'll hear most of the time the NAS goes down hard was because power was removed abruptly without giving the NAS the chance to power down properly.

 

Second is, a RAID NAS is priced to provide the best features and options compared to a single DAS storage device, which provides no redundancy on its own and fail the same way as your NAS. A NAS takes less time to recover from a single drive failure.  A single drive DAS failure takes longer.  So no, good money is not down the drain if you look at it in a view of minimal downtime.

 

For backup purposes, external drive options are the more economical approach or network backup to another Linkstation product preferably a Quad so you have 2 identical storage units. 

 

You need to ask yourself this question before going further.  How much value do you place on your data?  $1000?  $2000 or more?  Look at it in a way of buying insurance..  Everyone of us have car and home insurance and we keep paying them annually.  Why should you do that?  It is because, we put a value on the property we own ourselves and 3rd party liability.  Data is no different. 


JoshC

  • Big Bull
  • *****
  • Posts: 1110
Re: Quad 4TB RAID choice - which is best for me?
« Reply #11 on: January 08, 2010, 02:13:08 pm »

I second that!