So ahhh. anyone know when you will be able to just add an unlimited amount of drives?? Or at least more  than 16? maybe 40....

maybe 40....

 

 

There are likely some machine and/or OS limitations when you get above a certain number of physical drives.  For example, Linux assigns device ids "sda, sdb, ...".  I am not sure what would happen if you went over 26 (past "sdz").

 

unRAID's (single) parity drive provides excellent redundancy within its drive limits, but each drive added to the array dilutes its effectiveness lowering overall reliability.  After a certain number, the array is no longer reliable enough.  I could see going to 20+/-, but 40, even if you could get them working, would not be reliable enough for my needs.  If faced with needing 40T of online space today, I'd go to 2 or 3 separate arrays.

 

Today's unRAID can get you to 15T using 1T drives.  But if you do some Google searching you'll see that 4T drives are already in the works and likely will be available by 2009.  That would take unRAID's capacity (with 15 drives+parity) to 60T!

This has been covered in the past extensively.  I would say no just because you run into larger failure rates.  The probability of a drive failing right now exists but you run a greater risk with the amount of drives that you add.

 

http://lime-technology.com/forum/index.php?topic=1328.0

 

and

 

http://lime-technology.com/forum/index.php?topic=670.0

 

with the second post you can see Tom decided to go from 14 to 16 in 4.x

 

You'd be better off with 3 servers instead that way you're odds of drive failure and loosing data stay low....

To echo bjp999, I'd imagine that a 40-drive array and one failed drive would undermind one of the big benefits of unRAID.  At reasonable drive numbers, you can still access data "from" the failed drive as if it were still there.  However, once your drive count starts getting too big, the time that it would take to read 39 drives to recreate the data for one drive in real time would probably make that data unusable for media streaming purposes (what I use unRAID for). 

 

Of course, with a failed drive, you should replace and rebuild ASAP, but the number of drives could make that a "days" task instead of "hours." 

 

Plus, we have to remember that unRAID is a business...it might be pretty hard to sell Pro 2-packs if you can go unlimited on drives!  Maybe that's it...Tom's ultimate goal isn't to sell software, he wants to sell power supplies!!!

Heh, at least 20 or 26 now.

With a 15 drive machine and two external 5 port multipliers, that could be 26 drives available for usage.

24 for data, 1 parity, 1 cache.

 

 

I think the MD code itself has the ability to support 32, but there's a predefined hard limit.

 

/* The maximum number of disks per array that we support.
*/
#define MD_SB_DISKS                     16
/*
* RAID superblock.
* We are currently using 17/32 of this.
*/

Thank you all. that answers my questions. you guys are great!!! Have an ice cream sunday to celibrate your greatness.

Heh, at least 20 or 26 now.

With a 15 drive machine and two external 5 port multipliers, that could be 26 drives available for usage.

24 for data, 1 parity, 1 cache.

 

 

I think the MD code itself has the ability to support 32, but there's a predefined hard limit.

 

/* The maximum number of disks per array that we support.
*/
#define MD_SB_DISKS                     16
/*
* RAID superblock.
* We are currently using 17/32 of this.
*/

 

 

WeeboTech... where does that source code come from?  I didn't think Tom had released the modded MD code.... 

 

Jim

 

Heh, at least 20 or 26 now.

With a 15 drive machine and two external 5 port multipliers, that could be 26 drives available for usage.

24 for data, 1 parity, 1 cache.

 

 

I think the MD code itself has the ability to support 32, but there's a predefined hard limit.

 

/* The maximum number of disks per array that we support.
*/
#define MD_SB_DISKS                     16
/*
* RAID superblock.
* We are currently using 17/32 of this.
*/

 

 

WeeboTech... where does that source code come from?  I didn't think Tom had released the modded MD code.... 

 

Jim

 

You apparently have never looked in /usr/src/linux when you telnet into unRAID.  The source code for the modified MD driver has been there for a very very long time.  It is why there is no GPL notice to provide source code, because it is already provided.

 

There is no equivalent source for the management utility "emhttp" as it is not GPL.

 

Joe L.

Okay... I'm learnin' 

 

 

This has been covered in the past extensively.  I would say no just because you run into larger failure rates.  The probability of a drive failing right now exists but you run a greater risk with the amount of drives that you add.

 

http://lime-technology.com/forum/index.php?topic=1328.0

 

and

 

http://lime-technology.com/forum/index.php?topic=670.0

 

with the second post you can see Tom decided to go from 14 to 16 in 4.x

 

You'd be better off with 3 servers instead that way you're odds of drive failure and loosing data stay low....

 

Thats your personal view, which i can agree on. However, other people have other needs. I find it unnescessary to have such a hard limit in the software, let people have 32 drives with one parity if they so choose, (i guess on can add a "are you sure"-dialog-box if security is a concern). Wha I'm trying to say is, people should be limited by their own choices and needs setup-wise, not some limit in the software. For my personal use, i could see 32 drives beeing useful (using old drives from my file-server for secondary storage, backup for friends non-frequently accessed data and so on). however with that many i would prefer dual parity. Other people may have other uses for wich 16+ drives are useful.

A fair argument that has me in agreement.

 

I would however say that as soon as you go past the sensible limits in palce this now you should automatically give up the right to limetech support. Forum community support is always there obviously.

A fair argument that has me in agreement.

 

I would however say that as soon as you go past the sensible limits in palce this now you should automatically give up the right to limetech support. Forum community support is always there obviously.

 

A person should not have to give up support past a certain limit.

It should be an informed risk of the consumer.

If it's a small or a large array, If there are multiple disk failures, limetech support cannot do anything further.

I say let Tom decide policy on this one.

You could be right. However if HDD limits are removed support increases beyond the limits of a properly dimensioned product.

 

Or taken to one extreme. If i buy unRAID server and 10 more disks and it blows up can I ask for support.

 

My point is all sorts of things come into play when people will go inevitably crazy with disk additions and IMO its not fair to expect Tom to support it. The limit is in place for a sensible reason i think.