Double Protection

[Stucco]

I have had 2 X 2 TB hard drives fail in the past month.  Fortunately, thanks to unraid, I have had zero data loss in the process.

 

I am wondering if there is a way I can configure an extra layer of data protection.  I would be willing to lose a second drive to parity.  The idea would then be my two largest drives go to parity, and the rest are data, allowing any two drives to fail before data loss occurs.

 

I kind of doubt this is possible but I figured it was worth a shot.

[ohlwiler]

It is possible and in fact was on the map for a future version of unRAID. I would project it is at least three years down the road though. It is the only feature I really want.

[Brucey7]

I suspect double disk parity will require all parity protected drives spun-up for any writes, the maths for double parity is a lot more complex than single parity.

[bubbaQ]

I suspect double disk parity will require all parity protected drives spun-up for any writes, the maths for double parity is a lot more complex than single parity.

 

Depends on the scheme.  Reed-Solomon ECC will require all drives to spin up.  But diagonal parity requires only the data drive being written to, and the 2 parity drives to spin up.

[jimwhite]

What kind of drives failed?

[Brucey7]

I used to fund my movie collecting hobby by buying disks in the USA and selling them worldwide from eBay UK, I sold thousands of WD, Seagate and Hitachi.  I had between 2% and 5% fail within the first month (usually D.O.A. but the best was Hitachi and the worst was Seagate which are also the noisiest),  About another 5% fail under warranty from Seagate and WD but no failures after the first month from Hitachi.  Historically, the worst I ever had were Maxtor, but I haven't seen any of those in several years.

 

Also interestingly, 2TB failures on my own Thecus RAID5 boxes I kept in a cupboard and have just used them under windows to do a backup, with only one failing out of 9, and that didn't fail I just got fed up of the slow copy rate and threw it away.

 

I will only buy Hitachi Green drives for my own use and have 15 x 3TB of them in the server Rajahal delivered to Thailand for me 2 weeks ago.

[Kilack]

I have been using WD Greens and they had been pretty good up until a couple of weeks ago and then had two fail in the same week.

 

I would love to see a second parity drive given priority in unraid, 1 parity for 20 drives is really risky stuff, especially as a parity build will stress the rest of the drives.

Lucky I am not close to 20 drives and am still hovering around 8 drives which is right on the border of what is considered ok for 1 parity drive in the industry., though I'd prefer two parity disks for anything over 8 data drives for sure..

 

The other option of course would be allowing two or more arrays.. so we could at least break the 20 drives up and have a parity per array..

that could bring in lots of cool things too, like mirroring one array etc to the other.. reading off both arrays for faster striping reads etc...

 

ahhh lots of posibilities for unraid _if_ they have the time.......

[WeeboTech]

I have been using WD Greens and they had been pretty good up until a couple of weeks ago and then had two fail in the same week.

 

I would love to see a second parity drive given priority in unraid, 1 parity for 20 drives is really risky stuff, especially as a parity build will stress the rest of the drives.

Lucky I am not close to 20 drives and am still hovering around 8 drives which is right on the border of what is considered ok for 1 parity drive in the industry., though I'd prefer two parity disks for anything over 8 data drives for sure..

 

The other option of course would be allowing two or more arrays.. so we could at least break the 20 drives up and have a parity per array..

that could bring in lots of cool things too, like mirroring one array etc to the other.. reading off both arrays for faster striping reads etc...

 

ahhh lots of posibilities for unraid _if_ they have the time.......

 

When were these two drives that failed purchased?  

Were they purchased around the same time?

Do you do monthly parity checks?

 

[Kilack]

I have been using WD Greens and they had been pretty good up until a couple of weeks ago and then had two fail in the same week.

 

I would love to see a second parity drive given priority in unraid, 1 parity for 20 drives is really risky stuff, especially as a parity build will stress the rest of the drives.

Lucky I am not close to 20 drives and am still hovering around 8 drives which is right on the border of what is considered ok for 1 parity drive in the industry., though I'd prefer two parity disks for anything over 8 data drives for sure..

 

The other option of course would be allowing two or more arrays.. so we could at least break the 20 drives up and have a parity per array..

that could bring in lots of cool things too, like mirroring one array etc to the other.. reading off both arrays for faster striping reads etc...

 

ahhh lots of posibilities for unraid _if_ they have the time.......

 

When were these two drives that failed purchased?  

Were they purchased around the same time?

Do you do monthly parity checks?

 

 

They were purchased a couple of months ago, and yes both bought together. 

I havent been running unraid long enough to do monthly parity checks hehe

 

Anyway took the drives back to the shop where I bought them who replaced them with new ones on the spot.

[WeeboTech]

Unfortunately I've seen this very often. A number of drives bought together fail very closely to one another.

It's best to spread out your purchase over time and if you cannot, over multiple vendors.

 

Add in the monthly parity checks as that exercises the drives. I've had very few failures and I have 20 drives.

[ohlwiler]

I too have been very fortunate. I've been running 20 data drives for the past year. One drive had increasing reallocated sectors so I replaced it, and I've twice had disk disables that I fixed by reseating the SATA cable. Of the 22 drives in my array, I have a total of two reallocated sectors. With only one parity drive you need to keep a close eye on things.