jonlai9

After experiencing very slow performance yesterday, I looked into the system log and saw a lot of errors on my parity disk. Mar 1 08:53:59 LAI_SERVER kernel: md: disk0 read error (Errors) Mar 1 08:53:59 LAI_SERVER kernel: handle_stripe read error: 3585631368/0, count: 1 (Errors) Mar 1 08:53:59 LAI_SERVER kernel: md: disk0 read error (Errors) Mar 1 08:53:59 LAI_SERVER kernel: handle_stripe read error: 3585631376/0, count: 1 (Errors) (...) X infinity Lo and behold, this is the smart report. Is it dead? SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 183 183 051 Pre-fail Always - 26831 3 Spin_Up_Time 0x0027 167 164 021 Pre-fail Always - 6650 4 Start_Stop_Count 0x0032 098 098 000 Old_age Always - 2082 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0 9 Power_On_Hours 0x0032 083 083 000 Old_age Always - 12618 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 450 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 11 193 Load_Cycle_Count 0x0032 190 190 000 Old_age Always - 31616 194 Temperature_Celsius 0x0022 126 095 000 Old_age Always - 24 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 196 196 000 Old_age Always - 1416 198 Offline_Uncorrectable 0x0030 200 199 000 Old_age Offline - 39 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 144 001 000 Old_age Offline - 15170 SMART Error Log Version: 1 ATA Error Count: 104 (device log contains only the most recent five errors) CR = Command Register [HEX] FR = Features Register [HEX] SC = Sector Count Register [HEX] SN = Sector Number Register [HEX] CL = Cylinder Low Register [HEX] CH = Cylinder High Register [HEX] DH = Device/Head Register [HEX] DC = Device Command Register [HEX] ER = Error register [HEX] ST = Status register [HEX] Powered_Up_Time is measured from power on, and printed as DDd+hh:mm:SS.sss where DD=days, hh=hours, mm=minutes, SS=sec, and sss=millisec. It "wraps" after 49.710 days. Error 104 occurred at disk power-on lifetime: 12610 hours (525 days + 10 hours) When the command that caused the error occurred, the device was active or idle. After command completion occurred, registers were: ER ST SC SN CL CH DH -- -- -- -- -- -- -- 40 51 00 90 37 ad ee Error: UNC at LBA = 0x0ead3790 = 246232976 Commands leading to the command that caused the error were: CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name -- -- -- -- -- -- -- -- ---------------- -------------------- c8 00 00 d0 36 ad ee 08 14d+10:56:11.817 READ DMA c8 00 00 d0 2d ad ee 08 14d+10:56:11.603 READ DMA Error 103 occurred at disk power-on lifetime: 12610 hours (525 days + 10 hours) When the command that caused the error occurred, the device was active or idle. After command completion occurred, registers were: ER ST SC SN CL CH DH -- -- -- -- -- -- -- 40 51 00 d0 20 ad ee Error: UNC at LBA = 0x0ead20d0 = 246227152 Commands leading to the command that caused the error were: CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name -- -- -- -- -- -- -- -- ---------------- -------------------- c8 00 00 d0 20 ad ee 08 14d+10:56:07.923 READ DMA ef 10 02 00 00 00 a0 08 14d+10:56:07.923 SET FEATURES [Reserved for Serial ATA] ec 00 00 00 00 00 a0 08 14d+10:56:07.919 IDENTIFY DEVICE ef 03 46 00 00 00 a0 08 14d+10:56:07.919 SET FEATURES [set transfer mode] Error 102 occurred at disk power-on lifetime: 12610 hours (525 days + 10 hours) When the command that caused the error occurred, the device was active or idle. After command completion occurred, registers were: ER ST SC SN CL CH DH -- -- -- -- -- -- -- 40 51 00 d0 20 ad ee Error: UNC at LBA = 0x0ead20d0 = 246227152 Commands leading to the command that caused the error were: CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name -- -- -- -- -- -- -- -- ---------------- -------------------- c8 00 00 d0 20 ad ee 08 14d+10:56:05.166 READ DMA ef 10 02 00 00 00 a0 08 14d+10:56:05.166 SET FEATURES [Reserved for Serial ATA] ec 00 00 00 00 00 a0 08 14d+10:56:05.162 IDENTIFY DEVICE ef 03 46 00 00 00 a0 08 14d+10:56:05.162 SET FEATURES [set transfer mode] Error 101 occurred at disk power-on lifetime: 12610 hours (525 days + 10 hours) When the command that caused the error occurred, the device was active or idle. After command completion occurred, registers were: ER ST SC SN CL CH DH -- -- -- -- -- -- -- 40 51 00 d0 20 ad ee Error: UNC at LBA = 0x0ead20d0 = 246227152 Commands leading to the command that caused the error were: CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name -- -- -- -- -- -- -- -- ---------------- -------------------- c8 00 00 d0 20 ad ee 08 14d+10:56:02.409 READ DMA ef 10 02 00 00 00 a0 08 14d+10:56:02.409 SET FEATURES [Reserved for Serial ATA] ec 00 00 00 00 00 a0 08 14d+10:56:02.405 IDENTIFY DEVICE ef 03 46 00 00 00 a0 08 14d+10:56:02.405 SET FEATURES [set transfer mode] Error 100 occurred at disk power-on lifetime: 12610 hours (525 days + 10 hours) When the command that caused the error occurred, the device was active or idle. After command completion occurred, registers were: ER ST SC SN CL CH DH -- -- -- -- -- -- -- 40 51 00 d0 20 ad ee Error: UNC at LBA = 0x0ead20d0 = 246227152 Commands leading to the command that caused the error were: CR FR SC SN CL CH DH DC Powered_Up_Time Command/Feature_Name -- -- -- -- -- -- -- -- ---------------- -------------------- c8 00 00 d0 20 ad ee 08 14d+10:55:59.652 READ DMA ef 10 02 00 00 00 a0 08 14d+10:55:59.652 SET FEATURES [Reserved for Serial ATA] ec 00 00 00 00 00 a0 08 14d+10:55:59.648 IDENTIFY DEVICE ef 03 46 00 00 00 a0 08 14d+10:55:59.648 SET FEATURES [set transfer mode] SMART Self-test log structure revision number 1 Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error # 1 Short offline Completed without error 00% 5025 - # 2 Extended offline Aborted by host 90% 5005 - # 3 Extended offline Aborted by host 20% 4958 - # 4 Extended offline Aborted by host 90% 4954 - # 5 Extended offline Aborted by host 90% 4954 - # 6 Short offline Completed without error 00% 4942 - # 7 Short offline Completed without error 00% 4831 - # 8 Short offline Completed without error 00% 4830 - # 9 Short offline Aborted by host 10% 4825 - #10 Short offline Aborted by host 80% 4824 - #11 Short offline Aborted by host 10% 4824 - #12 Short offline Completed without error 00% 3237 - #13 Extended offline Completed without error 00% 34 - #14 Short offline Completed without error 00% 0 - SMART Selective self-test log data structure revision number 1 SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS 1 0 0 Not_testing 2 0 0 Not_testing 3 0 0 Not_testing 4 0 0 Not_testing 5 0 0 Not_testing Selective self-test flags (0x0): After scanning selected spans, do NOT read-scan remainder of disk. If Selective self-test is pending on power-up, resume after 0 minute delay.

Can someone provide me with an up to date guide to installing on 4.7? The info in the thread is very messy right now. Thanks!

Thanks again to this thread - verified with MD5 method that it is the SIL3132 card is causing me problems during parity check. I will buy the one from the seller charging $10 then, since rick.p suggested he had problems with the seller. Hope this works.

Thanks, from other threads I actually found this one which is cheaper too: http://www.ebay.com/itm/150719596527?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 I'm going to run the MD5 checks and see if the failures are drives on the SIL3132 controller. (Hopefully). Problems been happening for couple months now but I haven't had time to look into it until now. uh... warning on that one. After NINE WEEKS of no delivery, they finally refunded my money on the ones I ordered from them. They were pleasant but did stall a long time and they never came. Gives the expression "slow boat from China" new meaning. And they don't provide order tracking other than 'it shipped' Are you referring to one of those listings/sellers, or both? Can you be clear which seller you had problems with?

Thanks, from other threads I actually found this one which is cheaper too: http://www.ebay.com/itm/150719596527?ssPageName=STRK:MEWNX:IT&_trksid=p3984.m1439.l2649 I'm going to run the MD5 checks and see if the failures are drives on the SIL3132 controller. (Hopefully). Problems been happening for couple months now but I haven't had time to look into it until now.

It was recommended by someone else in a thread I had started on 'was this build good'. Will know soon I guess. So did it go well? I'm using the SIL3132 card from monoprice and I've been getting parity sync errors lately as well. Considering changing the card to see if that fixes the problem. Thanks.

I did 30 hours testing my RAM using the included memtest on the unRAID server, and seems like the RAM's fine. What's the next logical thing to test for? SATA cables? I also upgraded the PSU to a higher wattage one recently, what's the possibility that it's the PSU? Thanks.

Hey guys, I did a completely new parity sync after reseating my hardware and doing two parity checks in a row afterwards. I noticed that some of the sectors reporting parity problems are the same, but not all of them. Why is that? Is this because unRAID does not output all parity sector locations that have parity problems? How do I get a full list of the locations? First parity check: Jan 16 00:25:26 LAI_SERVER kernel: md: parity incorrect: 34151840 (Errors) Jan 16 00:28:10 LAI_SERVER kernel: md: parity incorrect: 59197904 (Errors) Jan 16 00:30:31 LAI_SERVER kernel: md: parity incorrect: 80629400 (Errors) Jan 16 00:30:51 LAI_SERVER kernel: md: parity incorrect: 83648168 (Errors) Jan 16 00:31:46 LAI_SERVER kernel: md: parity incorrect: 92013400 (Errors) Jan 16 00:32:25 LAI_SERVER kernel: md: parity incorrect: 97962976 (Errors) Jan 16 00:32:45 LAI_SERVER kernel: md: parity incorrect: 101035416 (Errors) Jan 16 00:33:08 LAI_SERVER kernel: md: parity incorrect: 104461352 (Errors) Jan 16 00:33:11 LAI_SERVER kernel: md: parity incorrect: 104967648 (Errors) Jan 16 00:33:26 LAI_SERVER kernel: md: parity incorrect: 107211600 (Errors) Jan 16 00:33:29 LAI_SERVER kernel: md: parity incorrect: 107769056 (Errors) Jan 16 00:33:39 LAI_SERVER kernel: md: parity incorrect: 109175016 (Errors) Jan 16 00:34:29 LAI_SERVER kernel: md: parity incorrect: 116807000 (Errors) Jan 16 00:34:33 LAI_SERVER kernel: md: parity incorrect: 117482464 (Errors) Jan 16 00:35:01 LAI_SERVER kernel: md: parity incorrect: 121635824 (Errors) Jan 16 00:35:37 LAI_SERVER kernel: md: parity incorrect: 127168056 (Errors) Jan 16 00:36:53 LAI_SERVER kernel: md: parity incorrect: 138736992 (Errors) Jan 16 00:37:07 LAI_SERVER kernel: md: parity incorrect: 140833408 (Errors) Jan 16 00:37:18 LAI_SERVER kernel: md: parity incorrect: 142469320 (Errors) Jan 16 00:37:50 LAI_SERVER kernel: md: parity incorrect: 147381888 (Errors) Second parity check: Jan 16 16:14:47 LAI_SERVER kernel: md: parity incorrect: 53036016 (Errors) Jan 16 16:15:06 LAI_SERVER kernel: md: parity incorrect: 55982672 (Errors) Jan 16 16:15:28 LAI_SERVER kernel: md: parity incorrect: 59197904 (Errors) Jan 16 16:17:18 LAI_SERVER kernel: md: parity incorrect: 75990408 (Errors) Jan 16 16:17:19 LAI_SERVER kernel: md: parity incorrect: 76226392 (Errors) Jan 16 16:17:48 LAI_SERVER kernel: md: parity incorrect: 80629400 (Errors) Jan 16 16:18:08 LAI_SERVER kernel: md: parity incorrect: 83648168 (Errors) Jan 16 16:18:28 LAI_SERVER kernel: md: parity incorrect: 86714608 (Errors) Jan 16 16:19:04 LAI_SERVER kernel: md: parity incorrect: 92013400 (Errors) Jan 16 16:19:21 LAI_SERVER kernel: md: parity incorrect: 94561408 (Errors) Jan 16 16:19:43 LAI_SERVER kernel: md: parity incorrect: 97962976 (Errors) Jan 16 16:20:01 LAI_SERVER kernel: md: parity incorrect: 100704048 (Errors) Jan 16 16:20:03 LAI_SERVER kernel: md: parity incorrect: 101035416 (Errors) Jan 16 16:20:26 LAI_SERVER kernel: md: parity incorrect: 104461352 (Errors) Jan 16 16:20:29 LAI_SERVER kernel: md: parity incorrect: 104967648 (Errors) Jan 16 16:20:51 LAI_SERVER kernel: md: parity incorrect: 108314768 (Errors) Jan 16 16:21:12 LAI_SERVER kernel: md: parity incorrect: 111476696 (Errors) Jan 16 16:21:47 LAI_SERVER kernel: md: parity incorrect: 116807000 (Errors) Jan 16 16:21:51 LAI_SERVER kernel: md: parity incorrect: 117472984 (Errors) Jan 16 16:21:51 LAI_SERVER kernel: md: parity incorrect: 117482464 (Errors) Thanks again.

Thanks. There might have been writes performed during the parity-sync I performed as I have set mover to run twice a day. I shall redo parity-sync tonight, making sure no writes are possible.

I replaced one of my data drives because it was showing some sector problems in SMART report. How can I go about debugging if the new drive has problems or not? SMART does not show problems and the old drive has been sent back to RMA already... I saw in the post below regarding the possible problem with version 4.7: Since I replaced one of my data drives and I am using v4.7, how do I know whether or not I am affected by this problem? How do I go about troubleshooting the problem? Do I have to parity-sync and subsequently parity check each time? Or is there a faster method? This might take a while... I will try to replace it with a spare set of RAM that I have available. Hope that changes things. Also, does it matter if there are operations to the array during the parity-sync or parity-check? Thanks again.

I removed my parity drive from the array and added it back. After parity-sync, I conducted another parity check, and it found errors within the first 5 minutes. However, the CURRENT_PENDING_SECTOR count on the parity drive is now 0. I decided to reseat all the SATA cables and RAM modules. Should I do a parity-correct after this, and then another parity check afterwards? One observation is that the sector that unRAID reports to have incorrect parity changes each time I run a parity check. They don't appear to be the same sectors each time. Does this imply that it is likely a RAM issue? Unfortunately I don't have time to do MemTest on the modules right now, however if this is the case I can swap a pair of older modules and try again. Since I recently replaced one of the drives, I'm also wondering if that might be an issue. I have seen other threads where changing the drive in unRAID 4.7 may cause this issue as well. Thanks.

I was just wondering, when I do the above and during the parity-sync procedure, does it matter if certain operations are writing to the array? For example, I have mover set so that it runs twice a day. Would it interfere with the parity-sync procedure or is unRAID smart enough to figure that out?

Thanks Joe, so if the parity drive is the only one with CURRENT_PENDING_SECTORS it can be safe to assume that the parity drive's the culprit and it's safe to trust my array, and instead rebuild parity according to the current array configuration?

Don't have access to them right now, but I know none of them have sector problems.

I am afriad that may invalidate my parity though, if it is indeed valid. Does anyone have any other thing I can try before getting that.

Thanks. I've posted the entire syslog that I have. syslog-2012-01-03.txt

Performed another parity check last night and got 162 errors, up 3 from 159 the night before Here's the parity drive's SMART report: === START OF INFORMATION SECTION === Device Model: WDC WD20EARS-00MVWB0 Serial Number: ,,, Firmware Version: 51.0AB51 User Capacity: 2,000,398,934,016 bytes Device is: Not in smartctl database [for details use: -P showall] ATA Version is: 8 ATA Standard is: Exact ATA specification draft version not indicated Local Time is: Tue Jan 3 16:11:53 2012 EST SMART support is: Available - device has SMART capability. SMART support is: Enabled === START OF READ SMART DATA SECTION === SMART overall-health self-assessment test result: PASSED General SMART Values: Offline data collection status: (0x84) Offline data collection activity was suspended by an interrupting command from host. Auto Offline Data Collection: Enabled. Self-test execution status: ( 0) The previous self-test routine completed without error or no self-test has ever been run. Total time to complete Offline data collection: (36180) seconds. Offline data collection capabilities: (0x7b) SMART execute Offline immediate. Auto Offline data collection on/off support. Suspend Offline collection upon new command. Offline surface scan supported. Self-test supported. Conveyance Self-test supported. Selective Self-test supported. SMART capabilities: (0x0003) Saves SMART data before entering power-saving mode. Supports SMART auto save timer. Error logging capability: (0x01) Error logging supported. General Purpose Logging supported. Short self-test routine recommended polling time: ( 2) minutes. Extended self-test routine recommended polling time: ( 255) minutes. Conveyance self-test routine recommended polling time: ( 5) minutes. SCT capabilities: (0x3035) SCT Status supported. SCT Feature Control supported. SCT Data Table supported. SMART Attributes Data Structure revision number: 16 Vendor Specific SMART Attributes with Thresholds: ID# ATTRIBUTE_NAME FLAG VALUE WORST THRESH TYPE UPDATED WHEN_FAILED RAW_VALUE 1 Raw_Read_Error_Rate 0x002f 200 200 051 Pre-fail Always - 0 3 Spin_Up_Time 0x0027 166 164 021 Pre-fail Always - 6683 4 Start_Stop_Count 0x0032 099 099 000 Old_age Always - 1003 5 Reallocated_Sector_Ct 0x0033 200 200 140 Pre-fail Always - 0 7 Seek_Error_Rate 0x002e 200 200 000 Old_age Always - 0 9 Power_On_Hours 0x0032 094 094 000 Old_age Always - 4868 10 Spin_Retry_Count 0x0032 100 100 000 Old_age Always - 0 11 Calibration_Retry_Count 0x0032 100 100 000 Old_age Always - 0 12 Power_Cycle_Count 0x0032 100 100 000 Old_age Always - 238 192 Power-Off_Retract_Count 0x0032 200 200 000 Old_age Always - 2 193 Load_Cycle_Count 0x0032 191 191 000 Old_age Always - 28542 194 Temperature_Celsius 0x0022 128 095 000 Old_age Always - 22 196 Reallocated_Event_Count 0x0032 200 200 000 Old_age Always - 0 197 Current_Pending_Sector 0x0032 200 200 000 Old_age Always - 15 198 Offline_Uncorrectable 0x0030 200 200 000 Old_age Offline - 0 199 UDMA_CRC_Error_Count 0x0032 200 200 000 Old_age Always - 0 200 Multi_Zone_Error_Rate 0x0008 200 200 000 Old_age Offline - 0 SMART Error Log Version: 1 No Errors Logged SMART Self-test log structure revision number 1 Num Test_Description Status Remaining LifeTime(hours) LBA_of_first_error # 1 Short offline Completed without error 00% 4831 - # 2 Short offline Completed without error 00% 4830 - # 3 Short offline Aborted by host 10% 4825 - # 4 Short offline Aborted by host 80% 4824 - # 5 Short offline Aborted by host 10% 4824 - # 6 Short offline Completed without error 00% 3237 - # 7 Extended offline Completed without error 00% 34 - # 8 Short offline Completed without error 00% 0 - SMART Selective self-test log data structure revision number 1 SPAN MIN_LBA MAX_LBA CURRENT_TEST_STATUS 1 0 0 Not_testing 2 0 0 Not_testing 3 0 0 Not_testing 4 0 0 Not_testing 5 0 0 Not_testing Selective self-test flags (0x0): After scanning selected spans, do NOT read-scan remainder of disk. If Selective self-test is pending on power-up, resume after 0 minute delay.

Thanks for your reponse, ixnu! Yea, other problems I've posted tend to have responses within a few hours (thanks to some of the awesome members here ) but I guess this may also be because people are away for the holidays right now =\ I didn't increase the size of any of my HDD's, so that's unlikely the cause of my problem specifically. I think my problem is more because of an improper shutdown, though because I've also replaced a HDD and added a new drive in the same month, I'm not sure. I will run another parity check soon (probably tonight) to see if the number of errors are increasing or not, and report back.

Hey everyone, I am running unRAID 4.7. My recent monthly parity check occured on the 1st at midnight and reported 121 errors when performing the parity check with NOCORRECT. I ran it once more with NOCORRECT and this time it reported 159 errors. I performed short SMART tests on all hard drives and no drives report errors. However, I notice that my parity drive has 15 under "Current Pending Sector" and nothing under Offline Uncorrectable, most likely because I don't turn off my server (it only updates this parameter if the computer is off, correct? And not when the hard drive is only spun down?). This led me to think that it may be the parity drive that is at fault. I was forced to do a hard shutdown about 1-2 weeks ago, which may also have contributed to some of this problem. Since my last successful parity check (a month ago), I have also replaced one of the drives (by adding a new precleared drive and rebuilding parity) and added in a new drive, but I don't think either should be a source of this problem. However, the fact that I received different errors between the two times performing the parity check is a bit of a concern to me. What exactly does this mean? What are my next steps? Should I run reiserfsck on all hard drives (except parity, of course) and check to see if those are intact? I read that bad memory could also lead to this problem. How likely is that in my case? I do not have physical access to the server for a couple weeks (debugging via Hamachi right now) so I can't even run memtest at the moment. I've attached the syslog since the first parity check, which shows the errors reported during the two parity checks. Thanks, and happy new year syslog_parity.txt

Worked, thanks!

Hi, I have attached the text output of the four commands. Thanks! Also, I tried restarting my server today and try installing again, but it still doesn't work. I clicked on Install 0.4.9 but it still only installs 0.4.8 only. pyload_1.txt pyload_2.txt pyload_3.txt pyload_4.txt

Hey prostuff! I tried to install it again, but doesn't seem to work. I'm still stuck on 0.4.8 after installation, and I get the folllowing message after installing: xargs: xargs.c:445: main: Assertion `bc_ctl.arg_max <= (131072-2048)' failed. xargs: xargs.c:445: main: Assertion `bc_ctl.arg_max <= (131072-2048)' failed. unzip: cannot find or open /boot/packages/, /boot/packages/.zip or /boot/packages/.ZIP. Installed pyload to /mnt/cache/.pyload pyLoad pyload.conf file already exists Created unraid.d directory Created init script, /etc/rc.d/unraid.d/rc.unraid_pyload Created unmenu start script, /boot/unmenu/43-unmenu_user_script_start_pyload Created unmenu start script, /boot/unmenu/43-unmenu_user_script_stop_pyload pyLoad started as root. Please go Here to setup pyLoad the rest of the way Do you know what's wrong? Thanks!

I just downloaded the new package to upgrade to 0.4.9 and when I downloaded the zip using the package, I got: (MD5 of existing downloaded file NOT matched - download may be corrupted or download URL no longer valid. Does anyone know what's wrong? thanks.

And if I understand correctly, after selecting the new drive as the drive to replace the old drive with, I simply click START and the array will automatically regenerate the files into the new empty drive? Thanks.

Hi, one of my data drives is showing signs of wear so I'm planning on replacing it with a new drive. I did some searching and found some steps on how to replace the drive, but none of them mention preclear. Where would the preclear script come into play? Would I first preclear on a separate channel first, and then replace the existing drive with it? Just want to make sure as I don't want to screw up. Thanks!