February 18, 201016 yr So I just put together my box. Booted up via flash drive running 4.5.1. I currently have an empty 1.5TB drive and an empty 320gig drive. I went in and told unraid to use the 1.5TB drive as parity and the 320gig as disk1. The main screen told me disk1 wasnt formatted so I formatted it. Now the system is saying Parity-Sync in progress and running at an estimated speed of 59,242 KB/sec. Since the data drive didnt have anything on it what exactly is the system doing? It looks like this parity sync is going to take a while. So at this point I should just let that finish?
February 18, 201016 yr Yep. What it is doing is initializing the parity disk. The initial format was to make the 320g drive able to store data. Then the parity calculation starts. All the drives (not including the parity drive) are "checksummed" and the value written to the parity drive. This parity needs to be written all the way out to the end of the parity drive, this is why the parity drive has to be as large as or larger than the largest drive in the system. This parity is what allows unraid to rebuild a lost drive - and why it can recover from a single lost drive but not two. Once you see how the parity works you can also see why replacing a drive with a smaller drive is not a simple task. This link - http://lime-technology.com/wiki/index.php?title=FAQ which should probably have much of it's contents incorporated into the user manual will explain a whole lot about how unraid works. Study up on that page - especially these links: http://lime-technology.com/wiki/index.php?title=FAQ#How_does_parity_work.3F http://lime-technology.com/wiki/index.php?title=FAQ#How_much_usable_space_will_I_get_from_an_unRAID_array.3F and http://lime-technology.com/wiki/index.php?title=FAQ#Is_unRAID_for_me.3F P.S. The drive combination you've used for your test is probably the least amazing setup you could have. You will only have 320G of disk space despite having almost 2T of drives in your array. If you can find another disk, even if it's only an 80, you'll see that the available space is equal to the size of all the drives EXCLUDING the parity disk.
February 18, 201016 yr So I just put together my box. Booted up via flash drive running 4.5.1. I currently have an empty 1.5TB drive and an empty 320gig drive. I went in and told unraid to use the 1.5TB drive as parity and the 320gig as disk1. The main screen told me disk1 wasnt formatted so I formatted it. Now the system is saying Parity-Sync in progress and running at an estimated speed of 59,242 KB/sec. Since the data drive didnt have anything on it what exactly is the system doing? It looks like this parity sync is going to take a while. So at this point I should just let that finish? Absolutely. let it finish. Parity does not work on files, but on bits. It does not care if the drive is completely empty or completely full, a parity calculation is made for every bit on the data disk(s) and the corresponding "bit" stored on the parity disk. At roughly 60MB/s it will take just about 7 hours. That will probably speed up to between 75 and 100MB/s once it gets past the size of the 320 Gig drive, so it will be done a bit sooner. (which is a reasonable speed .. about 4 times faster than my older IDE based server in fact) Once parity is initially calculated and written to the parity drive you should press the "Check" button on the management web-page to force the server to read the data it just wrote to the parity disk. Until that is done you have no idea if parity was written to the disk accurately. (You should not get any parity errors) If you do, you have errors on a subsequent parity check it usually indicated hardware problems of some type. Joe L.
February 18, 201016 yr Author Thanks guys. I'll read up on those links. I've been trying to read as much as I can but until I get the server up and see it in front of me alot of it doesnt sink in. Just wanted to make sure I was starting this right. P.S. The drive combination you've used for your test is probably the least amazing setup you could have. You will only have 320G of disk space despite having almost 2T of drives in your array. If you can find another disk, even if it's only an 80, you'll see that the available space is equal to the size of all the drives EXCLUDING the parity disk. Yeah, I understand that. I have another 1.5tb, 500gb, and 320gb drives to add to the system but some already have data on them in my freenas box so wanted to start with the drives I have in it and make sure I get it setup, then I'll work on migrating data and get the other drives installed in my new unraid box.
February 19, 201016 yr Author Well this seems to be a good sign. I let the parity-sync finish and since I've run a parity check twice with no errors.
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