January 18, 201115 yr I have just set up my first unRAID server, and it all seems to have gone fairly smoothly (other than a couple of failed SATA ports on my mobo!!). However, I was under the impression that unRAID would perform some sort of 'clearing' of the drives (i.e. by writing zero's to them), but this doesn't seem to have happened. It performed a quick 'format' and then they were ready to go. The parity drive took a long time to set up (about 10 hours), but that was it. So I have a couple of questions: 1) Is this normal, or have I missed a drive 'clearing' step out somewhere (I appreciate I haven't run the 'Pre-clear' script I have seen mentioned on the forum, but thought unRAID did it's own 'clear' process on any drive that hadn't been 'pre-cleared') 2) By not going through a 'clearing' step, have I not stress tested the drives enough to be added to the array. 3) If the answer to 2) is 'No'. Should I remove them from the array and run the 'Pre-clear' script on them instead? 4) Does the same go for the parity drive, or is this covered by the 10 hour parity set-up process? Thanks in advance.
January 18, 201115 yr Did you have unRAID setup prior to 4.7 beta version? What is your hardware setup, how large are the drives in question? What steps did you take to setup your array, did you assign data drives first, start the array, stop the array, then assign a parity drive?
January 18, 201115 yr a drive will not be "cleared" by unraid if no parity disk has yet been assigned, or the initial parity calculation not yet performed. The clearing is necessary to maintain parity, if parity protection already exists. Yes, if the disks are empty, you can use the preclear_disk.sh script to exercise them and clear them too. You'll need to un-assign them from the array first, as the script will not work on a disk assigned to the array. Please use the new version of the preclear_disk.sh script posted a few days ago on the first post in the original thread. It has a vastly easier output format to understand for most users. Joe L.
January 18, 201115 yr Author Hi BRiT, answers as follows: Did you have unRAID setup prior to 4.7 beta version? Nope, this is my very first set-up. I have used v4.7 because it has support for the WDEARS drives I am using, without messing about with jumpers. What is your hardware setup, how large are the drives in question? BFG 680i SLI mobo 4GB ram Core 2 CPU Drive are 3 x 2TB WDEARS (I have run the wdidle program to stop/minimise the head parking) Once everything is up and running I will be transferring data from an existing Drobo (3.2TB approx), then transfering the disks (3 x 2TB WDEARS + 2 x 1.5TB Samsung Spinpoint) out of it to the new unRAID, adding three older 250TB drives I have, and adding an old WD Raptor 74GB as a cache drive (once I have checked on this forum that a Raptor is a decent drive to use for the Cache). (I will be running the Pre-clear script etc on all the drives transferred over to the unRAID array) What steps did you take to setup your array, did you assign data drives first, start the array, stop the array, then assign a parity drive? In a round about way, yes. I had a problem with two sata ports on the mobo failing, the two which were to be used for the parity drive and the cache (eventually) - when trying to run the parity calculation it would stop anfter a minute and dreport 288 errors. So in essence the two data drives we up and running (and formatted), before the parity drive was up and running. I then changed the parity drive to a new sata port on the mobo, and then ran the initial parity calculation, which is what took 10 hours. Joe L. - Sorry, just to clarify, given that the parity drive is now in place and has performed its parity calculation, will this have 'cleared' the data drives, or is this only for disks added AFTER the parity drive has been set-up?
January 18, 201115 yr The drive clearing is only for adding drives to an existing array. A drive with all zero's will not have any effect on the parity so it can be installed into an existing array without breaking the parity protection. A new array does a parity build instead of clearing all the drives. The parity is just set to match any random data that may be on the data drives. It's quicker to do the parity build than to clear every drive in a new array. Don't worry, the array is good after you do one more test. You must now run a parity check and have it complete without any errors. The pre-clear is also a very good drive burn-in tool. It's up to you if you want to run it or not. Peter
January 18, 201115 yr Author OK, I can run the parity check then. My concern is that I have not stress tested the data drives, or indeed the parity drive, to weed out any weak drives. To be safe, should I really start from scratch, and run the pre-clear script on all three drives (including the parity drive)? Or am I just being over cautious?
January 18, 201115 yr OK, I can run the parity check then. My concern is that I have not stress tested the data drives, or indeed the parity drive, to weed out any weak drives. To be safe, should I really start from scratch, and run the pre-clear script on all three drives (including the parity drive)? Or am I just being over cautious? If you have the time, un-assign them and pre-clear them, then assign them again. Otherwise, enjoy your new server, but be watching more closely while you load them for errors, especially once you start to reuse the drives from the older devices, since you;ll be overwriting your original copy at that point.
January 18, 201115 yr Author Ok, thanks very much Joe. I have unassigned all three and have started the preclear running on them with 4 cycles. Thanks again.
January 19, 201115 yr Ok, thanks very much Joe. I have unassigned all three and have started the preclear running on them with 4 cycles. Thanks again. OK, I hope you are using the newest preclear_disk.sh script (new as of two days ago). It has a vastly improved final output report. 4 cycles with a 2TB drive will keep the disks busy for about 5+ days.
January 19, 201115 yr Wait can you preclear more than 1 drive at once? I'm about to get 3 2tb EARS drives and that would be great if I could knock out all three at the same time, or at least two.. Would running 3 telnet sessions work?
January 19, 201115 yr yes you can do this with several telnet sessions ... BUT be aware that everything depends on your hardware ... the more preclear's you start the slower it will go .... so depending how fast your hardware is will you get or get not a time benefit ... remember that pre clearing is not only the chore of writing 0 onto your disk it also burns in your "new" disk to see if it is dependable or not .... reason why a lot of people in the forums run 3 and more pre clear runs on the new disks to see if everything is ok with them ... before they trust their data to it ....
January 19, 201115 yr Wait can you preclear more than 1 drive at once? I'm about to get 3 2tb EARS drives and that would be great if I could knock out all three at the same time, or at least two.. Would running 3 telnet sessions work? There are three ways 1. Multiple telnet sessions 2. Multiple Virtual Consoles on the system console. (there are 6 available, use Alt-F1 through Alt-F6 to switch between them) Log in, start the first preclear running Press Alt-F2 to get the second login prompt, log in, start the second pre-clear going. Press Alt-F3 to get the third login prompt on the third virtual console, log in, start the third pre-clear. To see the progress, press Alt-F1 to go back to the first console, Alt-F2 to get back to the second, etc. 3. Install "screen" and use virtual "screen" sessions. See here: http://lime-technology.com/wiki/index.php?title=Configuration_Tutorial#Preclearing_With_Screen Joe L.
January 19, 201115 yr That sounds great, I *hope* my server could handle writing to 2 drives at once. Thanks for the answers!
January 19, 201115 yr I did 4 at once on my older Supermicro server and they all went at the same speed.
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