What's the best RAID array for fault tolerance [duplicate]What are the different widely used RAID levels and when should I consider them?what is exactly an URE?Need help with recovering RAID arrayRAID array Considerations - Any advice?Do I need a second RAID controller for fault-tolerance?SQL Server: One 12-drive RAID-10 array or 2 arrays of 8-drives and 4-drivesPEBKAC failure on Raid 1 array (striped) installationWindows 2008 Best Raid ConfigurationDell PERC H700 and 8 disk slots : what are my options to increase disk fault tolerance?RAID consideration for 24 Disk Arrayrecover highly degraded raid array

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What's the best RAID array for fault tolerance [duplicate]


What are the different widely used RAID levels and when should I consider them?what is exactly an URE?Need help with recovering RAID arrayRAID array Considerations - Any advice?Do I need a second RAID controller for fault-tolerance?SQL Server: One 12-drive RAID-10 array or 2 arrays of 8-drives and 4-drivesPEBKAC failure on Raid 1 array (striped) installationWindows 2008 Best Raid ConfigurationDell PERC H700 and 8 disk slots : what are my options to increase disk fault tolerance?RAID consideration for 24 Disk Arrayrecover highly degraded raid array






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2
















This question already has an answer here:



  • What are the different widely used RAID levels and when should I consider them?

    2 answers



When setting up a server, I was told it needs to have really good fault tolerance. What RAID array would give me the best fault tolerance?










share|improve this question














marked as duplicate by HBruijn, Gerald Schneider, Ward Apr 16 at 0:30


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.



















  • Please avoid asking subjective questions serverfault.com/help/dont-ask such as you have done. Please refer to the possible duplicate that HBrujin pointed out, though I noticed there was no mention of btrfs, or reword your question to follow this guide serverfault.com/help/how-to-ask . Though someone should mention something like a virtual SAN as they can survive the complete death of whole servers if setup right.

    – BeowulfNode42
    Apr 15 at 9:29











  • There's no "one weird trick to protecting your data". You need to define risk you're prepared to take vs. budget you can spend to mitigate the risk. For a start, if I was tasked to make a server fault tolerant, I'd reject that and ask about the requirements for the service and design fault tolerance from that point forwards, which might give me a completely different design around HA/clustering or containers or whatever, to meet the requirements vs. simply making the best you can of an individual server.

    – Rob Moir
    Apr 15 at 12:56

















2
















This question already has an answer here:



  • What are the different widely used RAID levels and when should I consider them?

    2 answers



When setting up a server, I was told it needs to have really good fault tolerance. What RAID array would give me the best fault tolerance?










share|improve this question














marked as duplicate by HBruijn, Gerald Schneider, Ward Apr 16 at 0:30


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.



















  • Please avoid asking subjective questions serverfault.com/help/dont-ask such as you have done. Please refer to the possible duplicate that HBrujin pointed out, though I noticed there was no mention of btrfs, or reword your question to follow this guide serverfault.com/help/how-to-ask . Though someone should mention something like a virtual SAN as they can survive the complete death of whole servers if setup right.

    – BeowulfNode42
    Apr 15 at 9:29











  • There's no "one weird trick to protecting your data". You need to define risk you're prepared to take vs. budget you can spend to mitigate the risk. For a start, if I was tasked to make a server fault tolerant, I'd reject that and ask about the requirements for the service and design fault tolerance from that point forwards, which might give me a completely different design around HA/clustering or containers or whatever, to meet the requirements vs. simply making the best you can of an individual server.

    – Rob Moir
    Apr 15 at 12:56













2












2








2


1







This question already has an answer here:



  • What are the different widely used RAID levels and when should I consider them?

    2 answers



When setting up a server, I was told it needs to have really good fault tolerance. What RAID array would give me the best fault tolerance?










share|improve this question















This question already has an answer here:



  • What are the different widely used RAID levels and when should I consider them?

    2 answers



When setting up a server, I was told it needs to have really good fault tolerance. What RAID array would give me the best fault tolerance?





This question already has an answer here:



  • What are the different widely used RAID levels and when should I consider them?

    2 answers







raid






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked Apr 15 at 3:59









Daniel L. VanDenBoschDaniel L. VanDenBosch

1112 bronze badges




1112 bronze badges





marked as duplicate by HBruijn, Gerald Schneider, Ward Apr 16 at 0:30


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.











marked as duplicate by HBruijn, Gerald Schneider, Ward Apr 16 at 0:30


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.









marked as duplicate by HBruijn, Gerald Schneider, Ward Apr 16 at 0:30


This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.














  • Please avoid asking subjective questions serverfault.com/help/dont-ask such as you have done. Please refer to the possible duplicate that HBrujin pointed out, though I noticed there was no mention of btrfs, or reword your question to follow this guide serverfault.com/help/how-to-ask . Though someone should mention something like a virtual SAN as they can survive the complete death of whole servers if setup right.

    – BeowulfNode42
    Apr 15 at 9:29











  • There's no "one weird trick to protecting your data". You need to define risk you're prepared to take vs. budget you can spend to mitigate the risk. For a start, if I was tasked to make a server fault tolerant, I'd reject that and ask about the requirements for the service and design fault tolerance from that point forwards, which might give me a completely different design around HA/clustering or containers or whatever, to meet the requirements vs. simply making the best you can of an individual server.

    – Rob Moir
    Apr 15 at 12:56

















  • Please avoid asking subjective questions serverfault.com/help/dont-ask such as you have done. Please refer to the possible duplicate that HBrujin pointed out, though I noticed there was no mention of btrfs, or reword your question to follow this guide serverfault.com/help/how-to-ask . Though someone should mention something like a virtual SAN as they can survive the complete death of whole servers if setup right.

    – BeowulfNode42
    Apr 15 at 9:29











  • There's no "one weird trick to protecting your data". You need to define risk you're prepared to take vs. budget you can spend to mitigate the risk. For a start, if I was tasked to make a server fault tolerant, I'd reject that and ask about the requirements for the service and design fault tolerance from that point forwards, which might give me a completely different design around HA/clustering or containers or whatever, to meet the requirements vs. simply making the best you can of an individual server.

    – Rob Moir
    Apr 15 at 12:56
















Please avoid asking subjective questions serverfault.com/help/dont-ask such as you have done. Please refer to the possible duplicate that HBrujin pointed out, though I noticed there was no mention of btrfs, or reword your question to follow this guide serverfault.com/help/how-to-ask . Though someone should mention something like a virtual SAN as they can survive the complete death of whole servers if setup right.

– BeowulfNode42
Apr 15 at 9:29





Please avoid asking subjective questions serverfault.com/help/dont-ask such as you have done. Please refer to the possible duplicate that HBrujin pointed out, though I noticed there was no mention of btrfs, or reword your question to follow this guide serverfault.com/help/how-to-ask . Though someone should mention something like a virtual SAN as they can survive the complete death of whole servers if setup right.

– BeowulfNode42
Apr 15 at 9:29













There's no "one weird trick to protecting your data". You need to define risk you're prepared to take vs. budget you can spend to mitigate the risk. For a start, if I was tasked to make a server fault tolerant, I'd reject that and ask about the requirements for the service and design fault tolerance from that point forwards, which might give me a completely different design around HA/clustering or containers or whatever, to meet the requirements vs. simply making the best you can of an individual server.

– Rob Moir
Apr 15 at 12:56





There's no "one weird trick to protecting your data". You need to define risk you're prepared to take vs. budget you can spend to mitigate the risk. For a start, if I was tasked to make a server fault tolerant, I'd reject that and ask about the requirements for the service and design fault tolerance from that point forwards, which might give me a completely different design around HA/clustering or containers or whatever, to meet the requirements vs. simply making the best you can of an individual server.

– Rob Moir
Apr 15 at 12:56










2 Answers
2






active

oldest

votes


















3














In classical hardware RAID world, RAID1 and RAID6 are the more reliable RAID levels.



In the more advanced software RAID world (MDRAID and ZFS), you can use 3-way mirroring or even triple parity scheme (ZFS only).



From a reliability standpoint, correctly configured ZFS pools probably are the state of the art.






share|improve this answer


































    1














    RAID-6 is, in my opinion, the best (at least, the best affordable), if fault tolerance is the most desired property, raid-5 being second best.



    It would seem like RAID-1 (or 10 if more speed is desired and money isn't an issue) might be the go-to solution, but I wouldn't recommend that.



    RAID levels 1 and 5 have in common that exactly one disk may fail, and no bad things will happen. Also, apart from complete disk failure, the array is resilient to single sectors becoming unreadable (as long as N-1 sectors with the corresponding number remain). With raid-1, in theory even as many as 50% of the array could fail and no bad things would happen, as long as it's strictly the "correct disks" that are failing. That is, never any two disks with the same index.



    In principle, you could also do raid-1 with two, three, or ten mirror copies if you like, but monetary constraints usually forbid that. After all, throwing two dozen extra disks at the problem doesn't precisely make the approach "inexpensive" (though the word "inexpensive" in RAID refers to the single disks within the array, but nobody would want to use a cheap disk in a RAID anyway).



    RAID-10 is somewhat inferior insofar as it is basically RAID-0 stacked on top of two (or maybe three) instances of RAID-1. Although each of them is fault-tolerant within its limits, if any single of these fail, the whole thing fails.



    RAID-5 is cheap (only one extra disk needed) and has actually been sufficient for most people because hey, when do two disks die at the same time? Never happens! Well, sadly it can happen, and it does happen. Also, it can happen that a sector becomes unreadable. Yeah, that never happens, it's sooooooo unlikely, right.



    Unluckily, when you need to re-sync after a failure, you must read every sector on all remaining disks. With modern disk capacities, that is a huge number. Huge number multiplied with unlikely-probably-never-happens will, unluckily result in a probability that is not at all impossible. It can happen that after one disk has failed, a sector goes bad. It can happen that a second disk (which has the same number of power-on hours) fails, especially when put under a 16-18-hour stress test during resync.



    RAID-6 is the same as RAID-5 except it can withstand two disks failing simultaneously. It does not matter which disks fail, there is no worst case. Any two disks go down, and you're still good to go.

    So when you have the first disk failing, it's not yet time for cold sweat. You are still good to go, and you still have redundancy in place. That is sooooooo much better compared to RAID-5, and it comes at the price of yet only one extra disk.






    share|improve this answer

























    • If performance is not important, RAID-6 can be considered, running RAID-6 on HDD for random write operations is a bad choise. RAID-10 is not so cost-efficient, but gives a best redundancy and performance.

      – batistuta09
      Apr 15 at 12:22



















    2 Answers
    2






    active

    oldest

    votes








    2 Answers
    2






    active

    oldest

    votes









    active

    oldest

    votes






    active

    oldest

    votes









    3














    In classical hardware RAID world, RAID1 and RAID6 are the more reliable RAID levels.



    In the more advanced software RAID world (MDRAID and ZFS), you can use 3-way mirroring or even triple parity scheme (ZFS only).



    From a reliability standpoint, correctly configured ZFS pools probably are the state of the art.






    share|improve this answer































      3














      In classical hardware RAID world, RAID1 and RAID6 are the more reliable RAID levels.



      In the more advanced software RAID world (MDRAID and ZFS), you can use 3-way mirroring or even triple parity scheme (ZFS only).



      From a reliability standpoint, correctly configured ZFS pools probably are the state of the art.






      share|improve this answer





























        3












        3








        3







        In classical hardware RAID world, RAID1 and RAID6 are the more reliable RAID levels.



        In the more advanced software RAID world (MDRAID and ZFS), you can use 3-way mirroring or even triple parity scheme (ZFS only).



        From a reliability standpoint, correctly configured ZFS pools probably are the state of the art.






        share|improve this answer















        In classical hardware RAID world, RAID1 and RAID6 are the more reliable RAID levels.



        In the more advanced software RAID world (MDRAID and ZFS), you can use 3-way mirroring or even triple parity scheme (ZFS only).



        From a reliability standpoint, correctly configured ZFS pools probably are the state of the art.







        share|improve this answer














        share|improve this answer



        share|improve this answer








        edited Apr 15 at 7:45

























        answered Apr 15 at 7:26









        shodanshokshodanshok

        28.6k3 gold badges52 silver badges97 bronze badges




        28.6k3 gold badges52 silver badges97 bronze badges


























            1














            RAID-6 is, in my opinion, the best (at least, the best affordable), if fault tolerance is the most desired property, raid-5 being second best.



            It would seem like RAID-1 (or 10 if more speed is desired and money isn't an issue) might be the go-to solution, but I wouldn't recommend that.



            RAID levels 1 and 5 have in common that exactly one disk may fail, and no bad things will happen. Also, apart from complete disk failure, the array is resilient to single sectors becoming unreadable (as long as N-1 sectors with the corresponding number remain). With raid-1, in theory even as many as 50% of the array could fail and no bad things would happen, as long as it's strictly the "correct disks" that are failing. That is, never any two disks with the same index.



            In principle, you could also do raid-1 with two, three, or ten mirror copies if you like, but monetary constraints usually forbid that. After all, throwing two dozen extra disks at the problem doesn't precisely make the approach "inexpensive" (though the word "inexpensive" in RAID refers to the single disks within the array, but nobody would want to use a cheap disk in a RAID anyway).



            RAID-10 is somewhat inferior insofar as it is basically RAID-0 stacked on top of two (or maybe three) instances of RAID-1. Although each of them is fault-tolerant within its limits, if any single of these fail, the whole thing fails.



            RAID-5 is cheap (only one extra disk needed) and has actually been sufficient for most people because hey, when do two disks die at the same time? Never happens! Well, sadly it can happen, and it does happen. Also, it can happen that a sector becomes unreadable. Yeah, that never happens, it's sooooooo unlikely, right.



            Unluckily, when you need to re-sync after a failure, you must read every sector on all remaining disks. With modern disk capacities, that is a huge number. Huge number multiplied with unlikely-probably-never-happens will, unluckily result in a probability that is not at all impossible. It can happen that after one disk has failed, a sector goes bad. It can happen that a second disk (which has the same number of power-on hours) fails, especially when put under a 16-18-hour stress test during resync.



            RAID-6 is the same as RAID-5 except it can withstand two disks failing simultaneously. It does not matter which disks fail, there is no worst case. Any two disks go down, and you're still good to go.

            So when you have the first disk failing, it's not yet time for cold sweat. You are still good to go, and you still have redundancy in place. That is sooooooo much better compared to RAID-5, and it comes at the price of yet only one extra disk.






            share|improve this answer

























            • If performance is not important, RAID-6 can be considered, running RAID-6 on HDD for random write operations is a bad choise. RAID-10 is not so cost-efficient, but gives a best redundancy and performance.

              – batistuta09
              Apr 15 at 12:22















            1














            RAID-6 is, in my opinion, the best (at least, the best affordable), if fault tolerance is the most desired property, raid-5 being second best.



            It would seem like RAID-1 (or 10 if more speed is desired and money isn't an issue) might be the go-to solution, but I wouldn't recommend that.



            RAID levels 1 and 5 have in common that exactly one disk may fail, and no bad things will happen. Also, apart from complete disk failure, the array is resilient to single sectors becoming unreadable (as long as N-1 sectors with the corresponding number remain). With raid-1, in theory even as many as 50% of the array could fail and no bad things would happen, as long as it's strictly the "correct disks" that are failing. That is, never any two disks with the same index.



            In principle, you could also do raid-1 with two, three, or ten mirror copies if you like, but monetary constraints usually forbid that. After all, throwing two dozen extra disks at the problem doesn't precisely make the approach "inexpensive" (though the word "inexpensive" in RAID refers to the single disks within the array, but nobody would want to use a cheap disk in a RAID anyway).



            RAID-10 is somewhat inferior insofar as it is basically RAID-0 stacked on top of two (or maybe three) instances of RAID-1. Although each of them is fault-tolerant within its limits, if any single of these fail, the whole thing fails.



            RAID-5 is cheap (only one extra disk needed) and has actually been sufficient for most people because hey, when do two disks die at the same time? Never happens! Well, sadly it can happen, and it does happen. Also, it can happen that a sector becomes unreadable. Yeah, that never happens, it's sooooooo unlikely, right.



            Unluckily, when you need to re-sync after a failure, you must read every sector on all remaining disks. With modern disk capacities, that is a huge number. Huge number multiplied with unlikely-probably-never-happens will, unluckily result in a probability that is not at all impossible. It can happen that after one disk has failed, a sector goes bad. It can happen that a second disk (which has the same number of power-on hours) fails, especially when put under a 16-18-hour stress test during resync.



            RAID-6 is the same as RAID-5 except it can withstand two disks failing simultaneously. It does not matter which disks fail, there is no worst case. Any two disks go down, and you're still good to go.

            So when you have the first disk failing, it's not yet time for cold sweat. You are still good to go, and you still have redundancy in place. That is sooooooo much better compared to RAID-5, and it comes at the price of yet only one extra disk.






            share|improve this answer

























            • If performance is not important, RAID-6 can be considered, running RAID-6 on HDD for random write operations is a bad choise. RAID-10 is not so cost-efficient, but gives a best redundancy and performance.

              – batistuta09
              Apr 15 at 12:22













            1












            1








            1







            RAID-6 is, in my opinion, the best (at least, the best affordable), if fault tolerance is the most desired property, raid-5 being second best.



            It would seem like RAID-1 (or 10 if more speed is desired and money isn't an issue) might be the go-to solution, but I wouldn't recommend that.



            RAID levels 1 and 5 have in common that exactly one disk may fail, and no bad things will happen. Also, apart from complete disk failure, the array is resilient to single sectors becoming unreadable (as long as N-1 sectors with the corresponding number remain). With raid-1, in theory even as many as 50% of the array could fail and no bad things would happen, as long as it's strictly the "correct disks" that are failing. That is, never any two disks with the same index.



            In principle, you could also do raid-1 with two, three, or ten mirror copies if you like, but monetary constraints usually forbid that. After all, throwing two dozen extra disks at the problem doesn't precisely make the approach "inexpensive" (though the word "inexpensive" in RAID refers to the single disks within the array, but nobody would want to use a cheap disk in a RAID anyway).



            RAID-10 is somewhat inferior insofar as it is basically RAID-0 stacked on top of two (or maybe three) instances of RAID-1. Although each of them is fault-tolerant within its limits, if any single of these fail, the whole thing fails.



            RAID-5 is cheap (only one extra disk needed) and has actually been sufficient for most people because hey, when do two disks die at the same time? Never happens! Well, sadly it can happen, and it does happen. Also, it can happen that a sector becomes unreadable. Yeah, that never happens, it's sooooooo unlikely, right.



            Unluckily, when you need to re-sync after a failure, you must read every sector on all remaining disks. With modern disk capacities, that is a huge number. Huge number multiplied with unlikely-probably-never-happens will, unluckily result in a probability that is not at all impossible. It can happen that after one disk has failed, a sector goes bad. It can happen that a second disk (which has the same number of power-on hours) fails, especially when put under a 16-18-hour stress test during resync.



            RAID-6 is the same as RAID-5 except it can withstand two disks failing simultaneously. It does not matter which disks fail, there is no worst case. Any two disks go down, and you're still good to go.

            So when you have the first disk failing, it's not yet time for cold sweat. You are still good to go, and you still have redundancy in place. That is sooooooo much better compared to RAID-5, and it comes at the price of yet only one extra disk.






            share|improve this answer













            RAID-6 is, in my opinion, the best (at least, the best affordable), if fault tolerance is the most desired property, raid-5 being second best.



            It would seem like RAID-1 (or 10 if more speed is desired and money isn't an issue) might be the go-to solution, but I wouldn't recommend that.



            RAID levels 1 and 5 have in common that exactly one disk may fail, and no bad things will happen. Also, apart from complete disk failure, the array is resilient to single sectors becoming unreadable (as long as N-1 sectors with the corresponding number remain). With raid-1, in theory even as many as 50% of the array could fail and no bad things would happen, as long as it's strictly the "correct disks" that are failing. That is, never any two disks with the same index.



            In principle, you could also do raid-1 with two, three, or ten mirror copies if you like, but monetary constraints usually forbid that. After all, throwing two dozen extra disks at the problem doesn't precisely make the approach "inexpensive" (though the word "inexpensive" in RAID refers to the single disks within the array, but nobody would want to use a cheap disk in a RAID anyway).



            RAID-10 is somewhat inferior insofar as it is basically RAID-0 stacked on top of two (or maybe three) instances of RAID-1. Although each of them is fault-tolerant within its limits, if any single of these fail, the whole thing fails.



            RAID-5 is cheap (only one extra disk needed) and has actually been sufficient for most people because hey, when do two disks die at the same time? Never happens! Well, sadly it can happen, and it does happen. Also, it can happen that a sector becomes unreadable. Yeah, that never happens, it's sooooooo unlikely, right.



            Unluckily, when you need to re-sync after a failure, you must read every sector on all remaining disks. With modern disk capacities, that is a huge number. Huge number multiplied with unlikely-probably-never-happens will, unluckily result in a probability that is not at all impossible. It can happen that after one disk has failed, a sector goes bad. It can happen that a second disk (which has the same number of power-on hours) fails, especially when put under a 16-18-hour stress test during resync.



            RAID-6 is the same as RAID-5 except it can withstand two disks failing simultaneously. It does not matter which disks fail, there is no worst case. Any two disks go down, and you're still good to go.

            So when you have the first disk failing, it's not yet time for cold sweat. You are still good to go, and you still have redundancy in place. That is sooooooo much better compared to RAID-5, and it comes at the price of yet only one extra disk.







            share|improve this answer












            share|improve this answer



            share|improve this answer










            answered Apr 15 at 10:56









            DamonDamon

            2111 silver badge2 bronze badges




            2111 silver badge2 bronze badges















            • If performance is not important, RAID-6 can be considered, running RAID-6 on HDD for random write operations is a bad choise. RAID-10 is not so cost-efficient, but gives a best redundancy and performance.

              – batistuta09
              Apr 15 at 12:22

















            • If performance is not important, RAID-6 can be considered, running RAID-6 on HDD for random write operations is a bad choise. RAID-10 is not so cost-efficient, but gives a best redundancy and performance.

              – batistuta09
              Apr 15 at 12:22
















            If performance is not important, RAID-6 can be considered, running RAID-6 on HDD for random write operations is a bad choise. RAID-10 is not so cost-efficient, but gives a best redundancy and performance.

            – batistuta09
            Apr 15 at 12:22





            If performance is not important, RAID-6 can be considered, running RAID-6 on HDD for random write operations is a bad choise. RAID-10 is not so cost-efficient, but gives a best redundancy and performance.

            – batistuta09
            Apr 15 at 12:22



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