GaryMaster Posted February 16, 2010 Share Posted February 16, 2010 Western Digital Caviar Green WD15EARS 1.5TB 64MB Cache SATA 3.0Gb/s 3.5" Bare Drive $99.99 + FS Promo Code: EMCYNZT27 http://www.newegg.com/Product/Product.aspx?Item=N82E16822136513&Tpk=WD15EARS Note that this is the new EARS 64MB advanced format drive. The deal is good today only (Tuesday, February 16th). Note the importance of aligning advanced format drives in unRAID to achieve good performance: http://lime-technology.com/forum/index.php?topic=5076.msg49831#msg49831 Quote Link to comment
tyrindor Posted February 16, 2010 Share Posted February 16, 2010 Oh man... Sweet deal. I just bought 3x 2TB EADS for $150 each. Now I don't have the money to jump in on this. Quote Link to comment
JDGJr Posted February 16, 2010 Share Posted February 16, 2010 Note the importance of aligning advanced format drives in unRAID to achieve good performance: http://lime-technology.com/forum/index.php?topic=5076.msg49831#msg49831 I remain confused on this issue. - I read somewhere on here that alignment was only needed on Windows, not Linux. - the link has a pretty chart, but no information on how to align the drives for better performance. Is there a way to make the drives perform better? Quote Link to comment
BRiT Posted February 16, 2010 Share Posted February 16, 2010 Yes, to make the drives perform better, install the Jumper. From the link: Setting the jumper on pins 7-8 of the WD advanced format drive corrects the alignment problem with unRAID. Quote Link to comment
GaryMaster Posted February 16, 2010 Author Share Posted February 16, 2010 - I read somewhere on here that alignment was only needed on Windows, not Linux. - the link has a pretty chart, but no information on how to align the drives for better performance. The linked thread has all of the information you need to resolve the issue. Even though most flavors of linux do not require any special action be taken by the user, the file system used by unraid does not currently configure this automagically for you. Quote Link to comment
JDGJr Posted February 16, 2010 Share Posted February 16, 2010 Yes, to make the drives perform better, install the Jumper. From the link: Setting the jumper on pins 7-8 of the WD advanced format drive corrects the alignment problem with unRAID. thank you. guess i'm not seeing bolded text today. question: I'm in the middle of pre-clearing 2 1.5TB drives without the jumper in place. Do i need to re-do the pre-clear after setting the jumper? Quote Link to comment
GaryMaster Posted February 16, 2010 Author Share Posted February 16, 2010 question: I'm in the middle of pre-clearing 2 1.5TB drives without the jumper in place. Do i need to re-do the pre-clear after setting the jumper? I will let Joe L. answer this since I think that is his baby. The jumper doesn't do anything other than remapping the sectors by 1. You will lose any data you had on the drive if you add data to it before you move the jumper. Then I would think that another preclear would be in order. Quote Link to comment
Joe L. Posted February 16, 2010 Share Posted February 16, 2010 question: I'm in the middle of pre-clearing 2 1.5TB drives without the jumper in place. Do i need to re-do the pre-clear after setting the jumper? I will let Joe L. answer this since I think that is his baby. However, the jumper doesn't do anything other than remapping the sectors by 1 so I don't see any need to pre-clear again. You will, however, lose any data you had on the drive if you add data to it before you move the jumper. It all depends on what it does to sector 0. If all of a sudden what was sector 1 is now visible as sector 0 you'll find the MBR all zeros and the drive completely unformatted as the partition table will also be all zeros. Easy enough to test. After you finish pre-clearing, power down, add the jumper, power up, run preclear_disk.sh -t /dev/sdX to test if it is still considered pre-cleared and has a proper pre-clear signature. If not, you can always run preclear_disk.sh once more (and use the "-n" option to skip the pre/post read phases to save some time) Joe L. Quote Link to comment
mifronte Posted February 16, 2010 Share Posted February 16, 2010 So if I plan on using the Windows alignment tool by WD first so that I can use it as a temporary storage on Windows XP, would I need to use the pin method to realign it when I decided to use it as a drive in an Unraid server? My guess is yes, but I am not a hard drive expert. Quote Link to comment
JDGJr Posted February 16, 2010 Share Posted February 16, 2010 Thanks Joe, but I stopped the preclear and restarted after applying the jumper. I'm not in a rush, and this seemed more certain. John Quote Link to comment
Joe L. Posted February 16, 2010 Share Posted February 16, 2010 Thanks Joe, but I stopped the preclear and restarted after applying the jumper. I'm not in a rush, and this seemed more certain. John You can still help with the test, but in reverse. After the pre-clear finishes, power down, remove the jumper, run the preclear_disk.sh -t dev/sdX to test it only. It does not write to the disk at all, but it will let you know if the pre-clear signature is visible (I'm guessing it will not be there) Once you perform that test, power down once more, put the jumper back on, and re-run with preclear_disk.sh -t /dev/sdX once more. It should still show as pre-cleared and you are ready to assign it to a slot in your server. Quote Link to comment
JDGJr Posted February 16, 2010 Share Posted February 16, 2010 will test when the preclears (doing 2 1.5TBs at the same time) complete - late today or tomorrow. Quote Link to comment
JDGJr Posted February 17, 2010 Share Posted February 17, 2010 After pre-clear, with jumper still installed, i get the following display. I get the bolded text on both drives - what does that mean? ######################################################################## Device Model: WDC WD15EARS-00Z5B1 Serial Number: WD-WMAVU1566796 Firmware Version: 80.00A80 User Capacity: 1,500,301,910,016 bytes Disk /dev/sda: 1500.3 GB, 1500301910016 bytes 255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors Units = sectors of 1 * 512 = 512 bytes Disk identifier: 0x00000000 Device Boot Start End Blocks Id System /dev/sda1 63 2930277167 1465138552+ 0 Empty Partition 1 does not end on cylinder boundary. ######################################################################## ============================================================================ == == DISK /dev/sda IS PRECLEARED == ============================================================================ Removing the jumper gives these results: ######################################################################## Device Model: WDC WD15EARS-00Z5B1 Serial Number: WD-WMAVU1566796 Firmware Version: 80.00A80 User Capacity: 1,500,301,910,016 bytes Disk /dev/sda: 1500.3 GB, 1500301910016 bytes 255 heads, 63 sectors/track, 182401 cylinders, total 2930277168 sectors Units = sectors of 1 * 512 = 512 bytes Disk identifier: 0x00000000 Disk /dev/sda doesn't contain a valid partition table ######################################################################## ============================================================================ == == Disk /dev/sda is NOT precleared == ============================================================================ Quote Link to comment
Joe L. Posted February 17, 2010 Share Posted February 17, 2010 It says that on almost every drive I've ever checked... It is a hold-over warning in fdisk from when there were a fixed number of sectors per cylinder on a disk and it warned if you created a partition with a partial cylinder at the end. Modern disks use a variable number of sectors per cylinder (and it is WAY more than 63) and fake the number reported to the bios. You can ignore the warning. It is meaningless. In the same way, you do NOT have 255 disk heads in your physical disk. If you did, you would have 127 1/2 platters.... not too likely. A google search seems to indicate your drive has three platters. Therefore, you have 6 heads, at most.... All this to make some older BIOS and partition table utilities happy. With the jumper installed, it looks the same as it did previously... it just is handling the mapping of fake 512 bytes sectors differently to its internal 4k sectors. Joe L. Quote Link to comment
JDGJr Posted February 17, 2010 Share Posted February 17, 2010 I just added the results w/o the jumper, now neither drive now shows that message (well, duh, the partition doesn't exist). And now neither shows as pre-cleared. thanks for the tool and info! Quote Link to comment
Joe L. Posted February 17, 2010 Share Posted February 17, 2010 I just added the results w/o the jumper, now neither drive now shows that message (well, duh, the partition doesn't exist). And now neither shows as pre-cleared. thanks for the tool and info! That confirms it. The jumper MUST be put into place before you install the drive in an unRAID server (or at least before you pre-clear it, and before you assign it to an array slot) If you pre-clear it, and then install the jumper, and then assign it to a slot in the array it will not be recognized as pre-cleared and unRAID will clear it for you. The offline time saved by pre-clearing would not be saved... Now, put the jumper back on the drive and it should once more show as pre-cleared. (If not, I apologize in advance) Joe L. Quote Link to comment
JDGJr Posted February 17, 2010 Share Posted February 17, 2010 No worries. jumper back in, partition is valid, test shows the drive is pre-cleared. Quote Link to comment
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