I first want to say UnRAID exceeded my expectations on recovery. I had a drive fail replaced it with a like size and in an hour was up and running again. So excellent job on an outstanding product! Now for my question which I am a bit confused on at this time. I just upgraded to the PLUS version and was looking at putting more drives in but I was not clear on the overall capacity of the drives. If I have a 2Tbs Parity Drive can I not exceed that limit on the overall set of drives? So if I had 2 500Gbs and 1 Tbs drive then I have a total of 2 Tbs and that is as far as I can go? That is where I am a bit confused. Because the price of 1Tbs drives is coming down and if I replace them all to 1Tbs drives then I would quickly exceeded my 2Tb Parity Drive. I do know that the normal drives cannot exceed the parity drive so I could not put one 3Tb drive into the UnRAID box but I was not clear of the overall total. Anyone that can help with this it would greatly appreciated. 

 

Thanks ahead

 

Greg

Each drive in the array can be of equal or lesser size to the array.

 

So if you have a 2TB Parity drive, each data drive you have needs to be 2TB or less.

So your capacity in this case would be 2TB x # of Data Drives.

 

For example,  if you have a 2TB Parity and 5 x 2TB Data Drives, your overall capacity would be 10TB

The only limitation is that each data drive must be equal to or smaller than the parity drive.  So the following configuration would be OK:

 

2 TB parity drive

1.0 TB data drive

1.5 TB data drive

2.0 TB data drive

 

but this configuration would not work:

 

1.5 TB parity drive

1.0 TB data drive

1.5 TB data drive

2.0 TB data drive

 

because the 2.0 TB data drive is larger than the 1.5 TB parity drive.

 

As long as all of the data drives are equal to or smaller than the parity drive you can add as many as you like.  (I suppose there is an absolute limit to the size of the array, but whatever it is it is higher than the number of drive bays in my case (and probably yours too), so it does not matter.)

unRAID doesn't backup every drive onto the parity. It's similar to RAID5 but without striping so you can have 1 drive fail and recover.

Excellent I got it now. Thank you so much for quick response.  That is what I was thinking but was not completely sure.

Could you change the title of your original post to include [sOLVED] ?  Thanks !

unRAID doesn't backup every drive onto the parity. It's similar to RAID5 but without striping so you can have 1 drive fail and recover.

Slightly more accurately, similar to RAID4, but without striping.    (RAID5 strips parity among all the disks, RAID4 has a single dedicated parity disk, exactly like unRAID.)

unRAID doesn't backup every drive onto the parity. It's similar to RAID5 but without striping so you can have 1 drive fail and recover.

Slightly more accurately, similar to RAID4, but without striping.    (RAID5 strips parity among all the disks, RAID4 has a single dedicated parity disk, exactly like unRAID.)

 

I don't get the problem? It's like RAID5 without striping. If you take either RAID4 or RAID5 and remove the striping then you get individual disks of data. In other words, they become the same thing.

Striping is spreading data over several drives (so the parts of one file will be spread among more disks.

 

striped parity means that part of the parity is on every disk (as is all the data, one individual disk is not readable or usable)

 

non-striped parity on a striped set means that the data is spread over all drives but the parity is on one disk.

 

raid5 = striped parity and striped data

raid4 = non striped parity and striped data

 

unraid is non-striped parity and non-striped data

 

So unraid is like raid4 without the striping ..

unraid is non-striped parity and non-striped data

 

Did you not read what I posted? If you remove the striping from RAID5 then what do you get? You get non striped parity and non-striped data or exactly what you just described unRAID as being.

 

unraid is non-striped parity and non-striped data

 

Did you not read what I posted? If you remove the striping from RAID5 then what do you get? You get non striped parity and non-striped data or exactly what you just described unRAID as being.

 

 

whoa whoa whoa.

relax.

 

RAID 4 without stripping is probably technically correct in a sense that RAID 4 has a dedicated parity drive, RAID 5 doesn't.

Sure, the answer is RAID4 if the question was which standard RAID level is unRAID the closest to. But, that question was never asked.

 

RAID4 and RAID5 both use 1 disk worth of parity to protect against a single disk failure and no striping is no striping.