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Flexraid help deciding - Page 3

post #61 of 165
12/6/12 at 8:19am
Quote:
Originally Posted by Guinness77 View Post

So one parity drive can protect against 2 or more drives failing at once?
Having multiple parity drives just protects the data in case the parity drive fails?
How many drives can you have on 1 parity?

No - each parity drive protects against a single drive failure.
One parity drive = protects against single drive failure.
Two parity drives = protects against two drive failures. Etc...
Under normal conditions the chances of two drives failing at once is slim so most stick with a single parity.

Of course none of this is going to help in the event of robbery, fire, flood, etc... and that's where Crashplan comes into play.
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post #62 of 165
12/6/12 at 8:21am
Quote:
Originally Posted by Mfusick View Post

You guys are over concerned with small files spanning drives.
It's a total non issue.
Lets say you have a music folder and you add a few mp3 files.. They go into that folder on that drive.
It's only when that drive fills up that it would get stored to another drive.
And not all drives. One drive. Inside a folder also named music.
If you broke down your array you would see you have a music folder on two different drives. Only reason it's on two drives is cause the first one was full.
I think everyone is over reacting to the whole "spanned across multiple drives small files" thing. It's not an issue.
When you break up your pool you don't have random small files all over the place.
The solution is of coarse in your pool have a small amount of top level drives with everything inside that.
Example: folder for video. All movies and TV shoes inside it. I have ten folders or categories in mine. HD not HD Bluray DVD TV shows Disney etc.. Those are my libraries I point my mediabrowser to. You have to set it up this way anyway if you want it to work properly.
Then on my pool I have folder called music: anything has to do with music inside. In folders. Organized.
Then I have folder called programs: anything has to do with programs inside
Then I have folder called documents: anything appropriate inside.
Then I have folder called misc.
That's it.
So of I break my array up then everything is still organized in just a few folders.
It's not like my music is all over the place.
It's all inside a music folder. Perhaps on two drives but that's only because my music drive filled up. Otherwise Flexraid would keep filling the original drives this is the default.

If this is true then I agree it should not be such a big deal and we shouldn't worry about files scattering all over the place.
Thanks
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post #63 of 165
12/6/12 at 8:26am
That video definitely cleared things up a lot, however I'm still a bit confused. My understanding of FlexRAID was that if I lose one drive, no problem to restore. If I lose two drives (assuming one parity drive), I can't restore both drives, but I CAN restore one of them. Is that not correct? Based on the video, I can't see how it would be.
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post #64 of 165
12/6/12 at 8:34am
Quote:
Originally Posted by ncarty97 View Post

That video definitely cleared things up a lot, however I'm still a bit confused. My understanding of FlexRAID was that if I lose one drive, no problem to restore. If I lose two drives (assuming one parity drive), I can't restore both drives, but I CAN restore one of them. Is that not correct? Based on the video, I can't see how it would be.

If you lose both a drive and a parity drive your screwed... assuming it's your only parity drive.

If you lose a parity drive you did not lose any data. So just replace that parity drive with a working drive and your parity back up resumes.

If you lose a drive- and have no parity drive too- you lost that drive and it's data.

At least I think so... haha.
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post #65 of 165
12/6/12 at 8:34am
Quote:
Originally Posted by hdkhang View Post


Are you using realtime parity protection? Last I remember, you can't do dual parity in that mode.


Is this true? I would really like to have dual parity or more with realtime.
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post #66 of 165
12/6/12 at 8:37am
Quote:
Originally Posted by Guinness77 View Post

Is this true? I would really like to have dual parity or more with realtime.

No.

You can use dual parity drives in real time.
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post #67 of 165
12/6/12 at 8:49am
Quote:
Originally Posted by Mfusick View Post

No.
You can use dual parity drives in real time.

That is good news. Thanks
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post #68 of 165
12/6/12 at 9:06am
Quote:
Originally Posted by Mfusick View Post

If you lose both a drive and a parity drive your screwed... assuming it's your only parity drive.
If you lose a parity drive you did not lose any data. So just replace that parity drive with a working drive and your parity back up resumes.
If you lose a drive- and have no parity drive too- you lost that drive and it's data.
At least I think so... haha.

I didn't mean one of the losses was a parity drive (didn't write that well).

I mean I have Drives A, B, C, D, E and F and parity drive P.;

Drive F, tired of life on the bottom of the rack, explodes and shoots shrapenel into Drive E. E & F are dead in suicide-murder double homicide.

So, is all the data lost on BOTH drives? I was under the impression that I could restore either E OR F, but not BOTH E & F, using the Parity drive.
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post #69 of 165
12/6/12 at 9:39am
Quote:
Originally Posted by Mfusick View Post

I will try at the above...
But I need to break it down so my ADD mind works properly.
It's definitely a different concept that you can back up 15TB of data with 3TB of space.

(5) 3TB drives with 4 as DATA drives (called DRU) and the remaining 3TB drive as a PPU (Parity drive) [back up]
So 4 data, one parity. Then you would have a pool size of 12TB. Yes. 4x3=12. 3TB Parity would provide backup if one of those drives went down. You could actually remove one of those drives and replace it with a blank 3TB drive and re-write the data back to it. Pretty cool if you ask me.
Parity keeps track of the total - it's math.
remember that all digital information is stored as either a 0 or a 1. it's never anything different.
so basically it reads each unit across all the drives and records the sum on parity drive.
Look at this:

That is a good example.
It records the totals across your drives and stores the answer on the parity drive. That is why the parity drive must be as large as your largest drive so it can hold that many parity totals.
If you subtracted one of those data drives you could figure out what is missing or what digit the missing drive had. Just look at the digits you know... and the answer and you can figure out what it was. That is basically how flexraid works.
You can back up more than 5 drives. I use it on 8. But as you increase drive counts you increase the chance of simultaneous drive failures. That's a problem.
Last-
Yes.
Your "pool" is always available. Flexraid is real time. Once you set it up- your drive is always available unless your doing a rebuild. You can get an email each day on the status if you want to know it's ok. It can email you your parity is up to date and correct if you need to know or want to be sure. I don't bother.
also,
Flexraid will allow you to use your older drives. You can then replace them with larger drives in future. I am doing this. replacing a 500GB drive with a 3TB gains you 2.5TB of space without needing another SATA port or SATA power. It's the way to do it when you find $$$ and good deals on large drives. Plus- it's good to replace older drives before they fail. it's just easier.

Quote:
Originally Posted by Dark_Slayer View Post

http://riceball.com/d/content/raid-5-parity-what-it-and-how-does-it-work

Quote:
Originally Posted by chappy16775 View Post

Parity explained:
http://www.youtube.com/watch?v=clvTWV1bgdI

Thanks guys! Makes sense now. I would rather understand how it done beofre I entrust data to it.
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post #70 of 165
12/6/12 at 10:04am
Quote:
Originally Posted by ncarty97 View Post

I didn't mean one of the losses was a parity drive (didn't write that well).
I mean I have Drives A, B, C, D, E and F and parity drive P.;
Drive F, tired of life on the bottom of the rack, explodes and shoots shrapenel into Drive E. E & F are dead in suicide-murder double homicide.
So, is all the data lost on BOTH drives? I was under the impression that I could restore either E OR F, but not BOTH E & F, using the Parity drive.

One parity drive protects you Against one drive failure at a time. It's expected you would get a replacement for a failed drive and rebuild it prior to another drive failing.

In order to have protection against two drives failing at the same time you would need two parity drives.

Hope that helps
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post #71 of 165
12/6/12 at 12:00pm
Could you recover 1 of those drives though? Or are both lost?
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post #72 of 165
12/6/12 at 12:07pm
Quote:
Originally Posted by Guinness77 View Post

Could you recover 1 of those drives though? Or are both lost?

You need two parity drives to recover two failed simultaneous data drives.

1 parity = protection against 1 data drive failure at once.

2 parity = protection and recovery from 2 data drive failures.
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post #73 of 165
12/6/12 at 12:32pm
Quote:
Originally Posted by Guinness77 View Post

Could you recover 1 of those drives though? Or are both lost?

You should be able to answer that question. Think about it. If you could recover one drive, then you would be back to a system with only one missing drive. So then you would be able to recover that drive. So you would have just recovered two failed drives from only one parity drive. Does not make sense.
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post #74 of 165
12/6/12 at 1:19pm
Thanks, that clears it up. I was just getting confused about things, I am new to this. I have been doing manual mirror backups of my data, and thinking about switching to something easier.

Thanks
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post #75 of 165
12/7/12 at 5:50am
Quote:
Originally Posted by Mfusick View Post

One parity drive protects you Against one drive failure at a time. It's expected you would get a replacement for a failed drive and rebuild it prior to another drive failing.
In order to have protection against two drives failing at the same time you would need two parity drives.
Hope that helps

Got it. That makes sense then.
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post #76 of 165
12/7/12 at 12:16pm
Surprised by the recent upswing in FlexRaid in this forum. Must be library and storage sizes are growing.
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post #77 of 165
12/7/12 at 4:20pm
Maybe people are getting more hard drives for christmas like me tongue.gif
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post #78 of 165
12/7/12 at 4:58pm
Quote:
Originally Posted by ncarty97 View Post

Got it. That makes sense then.

Keep in mind that it is recommended that you use 1 ppu for every 8 to 9 drus . Also , not unheard of but not likely that two drives would fail at the same time . However , the more data drives and parity drives you have the odds start to stack agents you . I don't think I would worry to much about multiple drive failures until I hit the 20 TB range .

My .02 smile.gif
Edited by flocko - 12/7/12 at 5:48pm
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post #79 of 165
12/7/12 at 5:02pm
I think it's 8-9 drives. Not 8-9TB. Big difference.

9TB is only 3 drives for me. I have 4 Seagate 3TB sitting here ready to go into my new server build.

You can go 8 HDD's of data drives to 1 PPU parity.
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post #80 of 165
12/7/12 at 5:12pm
Quote:
Originally Posted by Mfusick View Post

Surprised by the recent upswing in FlexRaid in this forum. Must be library and storage sizes are growing.

Could be that folks are finally figuring out what reality is cool.gif
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post #81 of 165
12/7/12 at 5:13pm
Quote:
Originally Posted by Mfusick View Post

I think it's 8-9 drives. Not 8-9TB. Big difference.
9TB is only 3 drives for me. I have 4 Seagate 3TB sitting here ready to go into my new server build.
You can go 8 HDD's of data drives to 1 PPU parity.

LOL . You are correct . My typo ... I have fixed it . Thanks
Edited by flocko - 12/7/12 at 5:50pm
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post #82 of 165
12/7/12 at 9:14pm
Quote:
Originally Posted by flocko View Post

LOL . You are correct . My typo ... I have fixed it . Thanks

I was getting nervous.


lol.... Cause I run about 8 per PPU.
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post #83 of 165
12/8/12 at 7:05am
Flocko how many PPU and how many DRU do you have in the Goliath ?
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post #84 of 165
12/27/12 at 12:02pm
I am trying to get some information about flexraid and the sites are really vague. They do not answer some basic questions. I am wondering how this is the case. They are saying that if you create one backup drive, you can then restore one drive failing? correct? Any one drive? Or is it only the drive you choose to backup? (that would not be very helpful). So if that one drive can replace any drive, how does it not have the power necessary to replace them all? In order to replace any one drive, it would have the information necessary to replace all of them, not just one if any drive out of the whatever number is covered. Make sense? Is there any issue how the drives are connected to the pc? By add in controller card? motherboard controller? usb connection? network connection? Most motherboards might only have 4 or 6 hard drive sata ports. As long as windows sees it, it can be used? They do not explain or mention this. Simple points.
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post #85 of 165
12/27/12 at 12:19pm
Quote:
Originally Posted by ariip View Post

I am trying to get some information about flexraid and the sites are really vague. They do not answer some basic questions. I am wondering how this is the case. They are saying that if you create one backup drive, you can then restore one drive failing? correct? Any one drive? Or is it only the drive you choose to backup? (that would not be very helpful). So if that one drive can replace any drive, how does it not have the power necessary to replace them all? In order to replace any one drive, it would have the information necessary to replace all of them, not just one if any drive out of the whatever number is covered. Make sense? Is there any issue how the drives are connected to the pc? By add in controller card? motherboard controller? usb connection? network connection? Most motherboards might only have 4 or 6 hard drive sata ports. As long as windows sees it, it can be used? They do not explain or mention this. Simple points.


Any drive. If you use a backup drive (parity drive) you can rebuild or recreate a failed drive. EXAMPLE: If you have 6 HDD's- it could be any of those 6. It's not just one specific drive that is backed up. It is all of your drives.

No issues with how connected. You can connect with controller card or direct to motherboard. USB or SATA- internal or external.

yes- if you need more ports get a card because motherboards have limited amount of sata ports (6 or 8 only)

I use the IBM1015 in IT mode. About $80. Works great. It's a preference of many in the flexraid forums.
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post #86 of 165
12/27/12 at 12:26pm
Quote:
Originally Posted by ariip View Post

They are saying that if you create one backup drive, you can then restore one drive failing? correct? Any one drive? Or is it only the drive you choose to backup? (that would not be very helpful). So if that one drive can replace any drive, how does it not have the power necessary to replace them all?
You can recreate from parity data and replace any single failed drive. Not one drive specifically but any of your data drives. If you have more than 8 data drives you should use 2 backup or “parity” drives.
For each parity drive you have - you can increase your tolerance for simultaneous drive failures.
Example: Two back up drives = any two drives could fail at the same time and your covered.

Quote:
Originally Posted by ariip View Post

In order to replace any one drive, it would have the information necessary to replace all of them, not just one if any drive out of the whatever number is covered. Make sense?

I am not sure it makes sense to you yet. But yes- a parity drive uses the information it contains cross checked against the non failed drives to determine the data that was on the failed drive.



imagine one drive above failed. Any one. Could you figure out the missing digit ???

That is how flexraid works.

Quote:
Originally Posted by ariip View Post

Is there any issue how the drives are connected to the pc? By add in controller card? motherboard controller? usb connection? network connection? Most motherboards might only have 4 or 6 hard drive sata ports. As long as windows sees it, it can be used? They do not explain or mention this. Simple points.

No issues. Most with a server use SATA ports on motherboard and additional SATA card.
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post #87 of 165
12/28/12 at 7:04am
Quote:
Originally Posted by Mfusick View Post

Flocko how many PPU and how many DRU do you have in the Goliath ?

Only 2 weeks late !!! Guess I need to learn what it means to "subscribe" Duh !!

5- dru @ 2-tb ea.
1- ppu @ 2-tb. This started out as a 3 tb wd green but failed . I had a spare 2 tb drive green that I am now using . I received a 3tb red in return but have not re installed it as I see no point in going through the pain again. The red is now a spare just collecting dust.
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post #88 of 165
12/28/12 at 9:12am
Quote:
Originally Posted by flocko View Post

Only 2 weeks late !!! Guess I need to learn what it means to "subscribe" Duh !!
5- dru @ 2-tb ea.
1- ppu @ 2-tb. This started out as a 3 tb wd green but failed . I had a spare 2 tb drive green that I am now using . I received a 3tb red in return but have not re installed it as I see no point in going through the pain again. The red is now a spare just collecting dust.

That is a nice spare to be collecting dust smile.gif

Adding it as your Parity would gain you an aditional 2TB since you free up the current parity.

Is that how you had the same error I was having when trying to build the new array ?

For some reason my flexraid won't pool or finish parity calculations. It did with 4 3TB seagates- but failed with the WD greens. I am going to try each green one at a time adding it in until I figure out which one it is. then just copy the data from it (it works and reads) then RMA just to be sure.

Problem is with full drives it takes FOREVER so trying adding one more drive at a time can take days/weeks frown.gif

I've had bad luck with green drives frown.gif
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post #89 of 165
12/28/12 at 9:14am
BTW your server is still one of the slickest looking I've seen... I'm jelly
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post #90 of 165
12/31/12 at 11:03am
Quote:
Originally Posted by bomberjim View Post

That's what makes UnRaid and Flexraid proprietary systems, and they're not telling exactly how they achieve "parity without striping".

It's essentially a RAID 4. This level of RAID keeps the parity information on one drive instead of distributing it among all drives in RAID 5.
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