January 31, 201313 yr New to unraid, pre clearing takes so long. Is it really necessary guys? Is your data important or easily replaceable? Also if you don't use preclear then when you add a disk to the array the whole array will be unavailable while unRAID writes zeros to the drive. The time will vary based on drive size but for a 2TB drive it will likely be ~9 hours. If you preclear it first your array stays available while the drive is being precleared. The other reason to preclear a drive is to exercise a drive to find a bad drives. Most drives die within the first ~100 hours or run to their warranty period or longer.
January 31, 201313 yr New to unraid, pre clearing takes so long. Is it really necessary guys? Is your data important or easily replaceable? Also if you don't use preclear then when you add a disk to the array the whole array will be unavailable while unRAID writes zeros to the drive. The time will vary based on drive size but for a 2TB drive it will likely be ~9 hours. If you preclear it first your array stays available while the drive is being precleared. The other reason to preclear a drive is to exercise a drive to find a bad drives. Most drives die within the first ~100 hours or run to their warranty period or longer. Thanks man for the details, I'm new here and learning all the time. So I guess I'll stop being impatient and just preclear all my drives This is going to take 1 - 2 weeks to have up and running with plugins shares per clears etc but slow and steady wins the race I guess.
February 1, 201313 yr New to unraid, pre clearing takes so long. Is it really necessary guys? Is your data important or easily replaceable? Also if you don't use preclear then when you add a disk to the array the whole array will be unavailable while unRAID writes zeros to the drive. The time will vary based on drive size but for a 2TB drive it will likely be ~9 hours. If you preclear it first your array stays available while the drive is being precleared. The other reason to preclear a drive is to exercise a drive to find a bad drives. Most drives die within the first ~100 hours or run to their warranty period or longer. Thanks man for the details, I'm new here and learning all the time. So I guess I'll stop being impatient and just preclear all my drives This is going to take 1 - 2 weeks to have up and running with plugins shares per clears etc but slow and steady wins the race I guess. I was the same way when I started. I did run preclear because I read about the array being off line until unRAID cleared it so I ran a single cycle. Ended up loosing a drive when it died and I had to replace it so then I went to what someone else recomended - 3 cycles. Thought about going to more but saw another discussion about diminishing returns so settled on 3 cycles as MY best compromise. Sure you can run more cycles and probably catch more faults but you also put more ware on the drive that way too. Now I preclear all drives even those that are not headed for the unRAID system with 3 cycles.
February 1, 201313 yr I was the same way when I started. I did run preclear because I read about the array being off line until unRAID cleared it so I ran a single cycle. Ended up loosing a drive when it died and I had to replace it so then I went to what someone else recomended - 3 cycles. Thought about going to more but saw another discussion about diminishing returns so settled on 3 cycles as MY best compromise. Sure you can run more cycles and probably catch more faults but you also put more ware on the drive that way too. Now I preclear all drives even those that are not headed for the unRAID system with 3 cycles. I think one cycle is enough for me man, it takes 30+ hours for 1 drive only 3TB. If I do 3 cycles it would take 90hours to preclear, that sounds like overkill in my opinion
February 2, 201313 yr I think one cycle is enough for me man, it takes 30+ hours for 1 drive only 3TB. If I do 3 cycles it would take 90hours to preclear, that sounds like overkill in my opinion Try and have a spare (precleared) drive on hand. That 30+ hour wait time after one of your drives fails seems more like 60+. I just added a 3TB parity drive and now I need to keep a look out for a good deal on a shelf-spare. I like the idea of having a separate box to preclear drives and test plugins. Best of luck with your system!
February 5, 201313 yr Hi Can someone have a quick look at the results attached for my new 3TB WD WD30EZRX which is going to become my new Parity drive. The drives has actually had 5 pre-clear cycles but I accidentally stopped the first cycle of 3 on the second cycle ( Ctrl C by mistake instead of Ctrl D whilst in screen). Second time around it completed after 84:20:31 To me all looks fine but i would like a second opinion as still new to unraid. preclear_finish__WD-WMC1T2102007_2013-02-05.txt preclear_rpt__WD-WMC1T2102007_2013-02-05.txt preclear_start__WD-WMC1T2102007_2013-02-05.txt
February 5, 201313 yr I think one cycle is enough for me man, it takes 30+ hours for 1 drive only 3TB. If I do 3 cycles it would take 90hours to preclear, that sounds like overkill in my opinion Try and have a spare (precleared) drive on hand. That 30+ hour wait time after one of your drives fails seems more like 60+. I just added a 3TB parity drive and now I need to keep a look out for a good deal on a shelf-spare. I like the idea of having a separate box to preclear drives and test plugins. Best of luck with your system! Cheers man, u too I'll try and grab a spare ASAP. Wanted to ask, are any of you guys per clearing through telnet, what happens when the session dies?
February 5, 201313 yr Hi Can someone have a quick look at the results attached for my new 3TB WD WD30EZRX which is going to become my new Parity drive. The drives has actually had 5 pre-clear cycles but I accidentally stopped the first cycle of 3 on the second cycle ( Ctrl C by mistake instead of Ctrl D whilst in screen). Second time around it completed after 84:20:31 To me all looks fine but i would like a second opinion as still new to unraid. looks good to me too.
February 5, 201313 yr I think one cycle is enough for me man, it takes 30+ hours for 1 drive only 3TB. If I do 3 cycles it would take 90hours to preclear, that sounds like overkill in my opinion Try and have a spare (precleared) drive on hand. That 30+ hour wait time after one of your drives fails seems more like 60+. I just added a 3TB parity drive and now I need to keep a look out for a good deal on a shelf-spare. I like the idea of having a separate box to preclear drives and test plugins. Best of luck with your system! Cheers man, u too I'll try and grab a spare ASAP. Wanted to ask, are any of you guys per clearing through telnet, what happens when the session dies? the preclear process terminates when the session dies. You should use the system console, or invoke "screen" first, then invoke the preclear process within "screen" ... that way, if the session dies you can reconnect and the preclear process will not terminate with the session.
February 5, 201313 yr ...Wanted to ask, are any of you guys per clearing through telnet, what happens when the session dies? What Joe said. Linux "screen" lets you reconnect if the session dies. Preclearing With Screen There is also a plugin.
February 6, 201313 yr I am attempting to use preclear for the first time. I've install preclear_disk.sh in the boot directory of my flash drive. I've installed the drive I want to preclear. It happens to be a WD Red 2TB and is bigger than my existing parity drive. When I boot up UnRAID, the management console recognizes that the drive is there (Disk 10) but if I do a /boot/preclear_disk.sh -l, it does not recognize the drive as available for preclear. Is that expected behavior? Thanks Dudley
February 6, 201313 yr It is expected. You cannot preclear a disk (i.e. Disk 10) that has been assigned to the array.
February 6, 201313 yr A disk needs to be outside the array to preclear, it's part of my procedure. Install disk Check detected in webgui Make sure removed from array and take note of serial number Run the preclear list command Run the preclear on drive Insert into array Your adding into array, so no drives available?
February 6, 201313 yr Thanks. I went in and unassigned it and was able to list it and start preclear.
February 6, 201313 yr Thanks. I went in and unassigned it and was able to list it and start preclear. Good to hear
February 12, 201313 yr I'm attempting to run the preclear script on a drive formated as HFS+. It seems to be running at ~5MB/s, meaning it'd take well over a day to simply pre-read it. Is this typical? And if so, is there any way to format the drive from my unraid box? A bit unusual...but it also seems like my unRAID box is the only one that can read the drive...it doesn't show up when attached through SATA->USB to any of my other machines. (I did not directly connect through SATA -- it used to be in an external case.)
February 12, 201313 yr I'm attempting to run the preclear script on a drive formated as HFS+. It seems to be running at ~5MB/s, meaning it'd take well over a day to simply pre-read it. Is this typical? And if so, is there any way to format the drive from my unraid box? A bit unusual...but it also seems like my unRAID box is the only one that can read the drive...it doesn't show up when attached through SATA->USB to any of my other machines. (I did not directly connect through SATA -- it used to be in an external case.) If through a USB connection, it would not surprise me for it to be slow. As far as how it was previously formatted, it makes absolutely no difference at all to the preclear script. It is reading raw disk blocks, not the file-system. The preclear script does not "format" the drive. It zeroes the entire drive (after first reading it entirely to allow the drive's SMART firmware to locate unreadable sectors) and then writes the entire drive, then re-reads to ensure what was written can be read back. If all that completes, it writes in the first 512 bytes a signature that unRAID will recognize telling it the disk has been pre-cleared. After assigning the drive to the unRAID array it will then present to you a button to "Format" the drive. Only that button should be used to Format the drive as it will format it in a way unRAID will identify as one of its drives. Joe L.
February 12, 201313 yr Hey, here are the results of clearing an 3 TB drive I have been using for a year now. Is everything OK? syslog_3tb.txt
February 12, 201313 yr Hey, here are the results of clearing an 3 TB drive I have been using for a year now. Is everything OK? looks really good to me.
February 12, 201313 yr If through a USB connection, it would not surprise me for it to be slow. As far as how it was previously formatted, it makes absolutely no difference at all to the preclear script. It is reading raw disk blocks, not the file-system. The preclear script does not "format" the drive. It zeroes the entire drive (after first reading it entirely to allow the drive's SMART firmware to locate unreadable sectors) and then writes the entire drive, then re-reads to ensure what was written can be read back. If all that completes, it writes in the first 512 bytes a signature that unRAID will recognize telling it the disk has been pre-cleared. After assigning the drive to the unRAID array it will then present to you a button to "Format" the drive. Only that button should be used to Format the drive as it will format it in a way unRAID will identify as one of its drives. Joe L. Ah, thanks for the clarification. If thats the case, if the drive is not empty, would that slow it down? I didn't specify last time -- but it is not connected through USB Thanks for your help.
February 12, 201313 yr If through a USB connection, it would not surprise me for it to be slow. As far as how it was previously formatted, it makes absolutely no difference at all to the preclear script. It is reading raw disk blocks, not the file-system. The preclear script does not "format" the drive. It zeroes the entire drive (after first reading it entirely to allow the drive's SMART firmware to locate unreadable sectors) and then writes the entire drive, then re-reads to ensure what was written can be read back. If all that completes, it writes in the first 512 bytes a signature that unRAID will recognize telling it the disk has been pre-cleared. After assigning the drive to the unRAID array it will then present to you a button to "Format" the drive. Only that button should be used to Format the drive as it will format it in a way unRAID will identify as one of its drives. Joe L. Ah, thanks for the clarification. If thats the case, if the drive is not empty, would that slow it down? I didn't specify last time -- but it is not connected through USB Thanks for your help. Its OK, there are thousands of things you did not specify that would affect the answers I did not give you. Let's start simple here: http://lime-technology.com/forum/index.php?topic=9880.0 The preclear process does not read files, or file systems, it reads the raw disk. It does not care if the disk is full or empty, formatted or not. if it is slow, then either the interface to the disk is having errors, or the disk is having errors, or something entirely else. Since I'm not clairvoyant, and neither is anyone else reading this forum, nobody can give you the answers if you elect to keep information to yourself. You mentioned USB connections in your prior post. Just how do you have the drive connected? Most drives can be read at between 50 and 150MB/s. If yours is slower, it is either a older/slower drive, or connected incorrectly, or defective. Joe L.
February 12, 201313 yr Yup, my apologies. I should have specified in my first post. I thought I had written it down, but apparently I rewrote my post multiple times before I finally submitted it. I'll be able to post logs when I get home. I stripped the drive out of the external case and put it into one of the drive bays (norco ss-500). When I mounted it to read the data off (modprobe hsfplus) it was copying at about 30 MB/s, and slowed to about ~5MB/s before I stopped it. I'm inclined to think either a) the drive is dying or b) I may have some bad wiring issues. I wrongly assumed it was something else since I had a drive that was reading at a similar pace until i reformatted it but I didn't isolate all variables (I plugged it back in in a different bay). Thanks for your insight edit: I should be able to figure it out from here. Thanks!
February 13, 201313 yr My latest preclear on a brand new drive. it was purchased as an external drive, but i removed the drive to use with unRAID. it looks okay, but there is one thing that concerns me, and confuses me... ========================================================================1.13 == invoked as: ./preclear_disk.sh /dev/sde == WL3000GSA6472C WOL240243956 == Disk /dev/sde has been successfully precleared == with a starting sector of 1 == Ran 1 cycle == == Using :Read block size = 8225280 Bytes == Last Cycle's Pre Read Time : 8:27:08 (98 MB/s) == Last Cycle's Zeroing time : 7:13:44 (115 MB/s) == Last Cycle's Post Read Time : 19:00:23 (43 MB/s) == Last Cycle's Total Time : 34:42:14 == == Total Elapsed Time 34:42:14 == == Disk Start Temperature: 31C == == Current Disk Temperature: 30C, == ============================================================================ ** Changed attributes in files: /tmp/smart_start_sde /tmp/smart_finish_sde ATTRIBUTE NEW_VAL OLD_VAL FAILURE_THRESHOLD STATUS RAW_VALUE End-to-End_Error = 100 100 97 near_thresh 0 Airflow_Temperature_Cel = 70 69 0 ok 30 Temperature_Celsius = 120 119 0 ok 30 No SMART attributes are FAILING_NOW 0 sectors were pending re-allocation before the start of the preclear. 0 sectors were pending re-allocation after pre-read in cycle 1 of 1. 0 sectors were pending re-allocation after zero of disk in cycle 1 of 1. 6 sectors are pending re-allocation at the end of the preclear, a change of 6 in the number of sectors pending re-allocation. 0 sectors had been re-allocated before the start of the preclear. 0 sectors are re-allocated at the end of the preclear, the number of sectors re-allocated did not change. ============================================================================ it says 6 sectors are pending re-allocation, but then it says 0 were re-allocated why didn't it re-allocate them, and what should I do now, if anything? I am pretty much out of space, so was hoping i could start using this drive, but I'd MUCH prefer to not have avoidable problems later, so I'm going to wait for feedback before proceeding. I have a similar report for the other disk i pre-cleared, which used to be my cache drive, but I replaced that with a 500GB drive, and want to put this 1TB drive into storage usage, but again, not sure if it's "okay" to do so, for the same reason... ========================================================================1.13 == invoked as: ./preclear_disk.sh /dev/sdk == SAMSUNG HD103UJ S13PJDWS337885 == Disk /dev/sdk has been successfully precleared == with a starting sector of 64 == Ran 1 cycle == == Using :Read block size = 8225280 Bytes == Last Cycle's Pre Read Time : 3:40:03 (75 MB/s) == Last Cycle's Zeroing time : 2:58:14 (93 MB/s) == Last Cycle's Post Read Time : 7:10:28 (38 MB/s) == Last Cycle's Total Time : 13:49:45 == == Total Elapsed Time 13:49:45 == == Disk Start Temperature: 25C == == Current Disk Temperature: 26C, == ============================================================================ ** Changed attributes in files: /tmp/smart_start_sdk /tmp/smart_finish_sdk ATTRIBUTE NEW_VAL OLD_VAL FAILURE_THRESHOLD STATUS RAW_VALUE Airflow_Temperature_Cel = 74 75 0 ok 26 Temperature_Celsius = 74 75 0 ok 26 Soft_Read_Error_Rate = 99 100 0 ok 54 No SMART attributes are FAILING_NOW 5 sectors were pending re-allocation before the start of the preclear. 7 sectors were pending re-allocation after pre-read in cycle 1 of 1. 0 sectors were pending re-allocation after zero of disk in cycle 1 of 1. 10 sectors are pending re-allocation at the end of the preclear, a change of 5 in the number of sectors pending re-allocation. 0 sectors had been re-allocated before the start of the preclear. 0 sectors are re-allocated at the end of the preclear, the number of sectors re-allocated did not change. ============================================================================
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