CowboyRedBeard Posted January 28, 2019 Share Posted January 28, 2019 (edited) So I'm going to upgrade from my i7-3770 to a dual Xeon e5 setup. For this I bought 2 new (not refurb) 8TB Segate drives, initially I was planning on replacing the existig single parity drive I have which is a refurb that's a few years old with these two. Then adding that old parity drive to the array. But, greed, and thinking about it.... Should I do dual parity drives, or just add the second one to the array to increase my storage? What's the common plan around this? I know everyone has different needs and uses. But is it more common than not to have dual parity drives? Through what I've read, basically the only function of dual parity drives is to ensure you can fail 2 drives and not loose data. And that being, 1 array drive + the parity at the same time. Right? If so, how frequently does something like that actually happen? Attached is what I have today... I use unraid mainly for Plex and a few VMs that are remote workstations. What's your thoughts on dual parity? That's a lot of money for something that seems like winning the lottery of suckage. However, I'm only at 42% usage presently, and at my present rate of additional data per month it might be a few years before I hit capacity. *Also, I keep the VMs on that M2 drive at the bottom. Edited January 28, 2019 by CowboyRedBeard Quote Link to comment
CowboyRedBeard Posted January 28, 2019 Author Share Posted January 28, 2019 Both new disks passed preclear looking pretty well the same, so I'm assuming they're good to go: ############################################################################################################################ # # # unRAID Server Preclear of disk BBBBBBB # # Cycle 1 of 1, partition start on sector 64. # # # # # # Step 1 of 5 - Pre-read verification: [15:28:30 @ 143 MB/s] SUCCESS # # Step 2 of 5 - Zeroing the disk: [15:23:23 @ 144 MB/s] SUCCESS # # Step 3 of 5 - Writing unRAID's Preclear signature: SUCCESS # # Step 4 of 5 - Verifying unRAID's Preclear signature: SUCCESS # # Step 5 of 5 - Post-Read verification: [15:32:49 @ 142 MB/s] SUCCESS # # # # # # # # # # # # # # # ############################################################################################################################ # Cycle elapsed time: 46:24:47 | Total elapsed time: 46:24:47 # ############################################################################################################################ ############################################################################################################################ # # # S.M.A.R.T. Status default # # # # # # ATTRIBUTE INITIAL CYCLE 1 STATUS # # 5-Reallocated_Sector_Ct 0 0 - # # 9-Power_On_Hours 0 46 Up 46 # # 183-Runtime_Bad_Block 0 0 - # # 184-End-to-End_Error 0 0 - # # 187-Reported_Uncorrect 0 0 - # # 190-Airflow_Temperature_Cel 27 36 Up 9 # # 197-Current_Pending_Sector 0 0 - # # 198-Offline_Uncorrectable 0 0 - # # 199-UDMA_CRC_Error_Count 0 0 - # # # # # # # ############################################################################################################################ # SMART overall-health self-assessment test result: PASSED # ############################################################################################################################ --> ATTENTION: Please take a look into the SMART report above for drive health issues. --> RESULT: Preclear Finished Successfully!. Quote Link to comment
trurl Posted January 28, 2019 Share Posted January 28, 2019 The more disks you have the more justification there is for another parity. If you are careful (always check all connections when mucking about in the case) and diligent (setup Notifications to notify you immediately by email or other agent when there is a problem) then with only 5 data it probably makes more sense to add another data disk instead of another parity. Another approach would be to replace one of your smaller disks with the new larger disk. That way you get more capacity without increasing the disk count. Quote Link to comment
JorgeB Posted January 28, 2019 Share Posted January 28, 2019 Why cover the disk models? Was curious what model are the 6.3TB disks... Quote Link to comment
CowboyRedBeard Posted January 29, 2019 Author Share Posted January 29, 2019 I'm just paranoid I guess... hah https://www.amazon.com/5700RPM-Cache-6-0Gb-Internal-Desktop/dp/B00UCP11U6 Quote Link to comment
SkippyAlpha Posted January 29, 2019 Share Posted January 29, 2019 (edited) One more thing, the second parity drive is not just a copy of the first parity drive, it actually goes through another algorithm (that I believe is actually sort of cpu heavy) to calculate the second disk. This means you can lose any 2 drives, not just 1 data + 1 parity drive at once. It could be for example, 2 data drives dying, and you would be fine. From the way you worded your question, just wanted to clear that up Edit: I do agree with them though, for your number of disks I think just 1 parity is appropriate. I personally moved to 2 parities around the 12 disk mark I believe. Edited January 29, 2019 by Sven88 Quote Link to comment
Frank1940 Posted January 30, 2019 Share Posted January 30, 2019 IF you want a bit of statistics on reliability of parity protected arrays and the probability of data loss, look at this thread: https://forums.unraid.net/topic/50504-dual-or-single-parity-its-your-choice/ It is also important to realize that data loss due to disk failure with a dual parity setup is not as likely as a lot of other ways you can lose your data! When making a move to dual parity from single parity, it is important that you address those areas as well. 1 Quote Link to comment
trurl Posted January 30, 2019 Share Posted January 30, 2019 25 minutes ago, Frank1940 said: It is also important to realize that data loss due to disk failure with a dual parity setup is not as likely as a lot of other ways you can lose your data! You must have a backup of anything important and irreplaceable regardless of how many parity disks you have. Quote Link to comment
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