G+_Eddie Foy Posted June 10, 2015 Share Posted June 10, 2015 Setting up a new NAS. Any reason to chop it up into different volumes? (4 x 6TB in RAID 5) Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 10, 2015 Share Posted June 10, 2015 #1 Don't use RAID 5 with 6TB drives. To explain why exactly lots of reading is required: http://pastebin.com/RiZccgAE Those 17 articles should cover everything RAID and the changes over the past 7 years or so. Also, no, no reason to split an array up. If you really feel the need you can add quotas at the share level (normally I'd say do it at the partitioning level, but the NAS most likely just handles that bit.) Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted June 10, 2015 Author Share Posted June 10, 2015 Gonna go for the single volume. Thanks. If it was a 6+ drive array I'd go RAID 6. (If I feel the need to get the expansion unit, then I'll migrate to 6) I don't see the perk dropping to 12TB of storage in a raw 24TB array. Dropping 2 drive's worth of space for a little extra safety, I dunno. Yeah 2(50%) of my drives can fail at the same time and I'll be ok. That likelihood, well lets just say Hitler will probably be making snow angels first. (if 2 out of the 4 die, most likely all 4 will die at the same time.) I'm ok with the only 1 drive can fail problem. Its risk management. I can use bullet proof cladding on my house so I don't get killed by a stray bullet in a drive by. Money well spent? Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 10, 2015 Share Posted June 10, 2015 Eddie Foy So you feel comfortable running an array that's guaranteed to fail a rebuild? You're actually better off going RAID 0 in this case. Ignore the "X number of drives can fail", it's a red herring or a tree in a forest in this case. If a drive in that array fails, it will NEVER rebuild. RAID 10 is the new rule of thumb for those in the know. RAID 6 can still be acceptable, tho slow. RAID 5 fails at reliability and speed. If you really want to get into advanced stuff we can start talking software defined storage and no RAID what so ever. You really need at least 3 storage units to do that properly tho, so probably way outside the use cases here (TWiET topic!) Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 10, 2015 Share Posted June 10, 2015 http://www.zdnet.com/blog/storage/why-raid-5-stops-working-in-2009/162 http://www.zdnet.com/blog/storage/why-raid-6-stops-working-in-2019/805 http://www.smbitjournal.com/2012/11/choosing-a-raid-level-by-drive-count Link to comment Share on other sites More sharing options...
G+_Eddie Foy Posted June 10, 2015 Author Share Posted June 10, 2015 I'm still not sold strictly on theoretical situations. Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 10, 2015 Share Posted June 10, 2015 Ok Eddie, if you know of any person or organization that is going to fund a project to test millions of hard drives for hundreds of years let us all know, until then all we've got are theories. All the circumstantial evidence we've seen points to the theory being true. I'll admit I didn't believe it myself for a long time. Then I had a NAS box fail to rebuild a RAID 5 array 3 times in a row with no drive failures. (This was a 4 x 1TB array with the worst possible drives at the time, still not a fan of WD Green.) Don't take my word for it, check the rest of us IT people's opinion out! (http://community.spiceworks.com/storage) Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 10, 2015 Share Posted June 10, 2015 http://www.smbitjournal.com/2012/05/when-no-redundancy-is-more-reliable Link to comment Share on other sites More sharing options...
G+_Fr. Robert Ballecer, SJ Posted June 10, 2015 Share Posted June 10, 2015 Travis Hershberger?? We had Allyn Malventano? ?on TWiET a few weeks back. He debunked the "RAID 5 is dead" FUD. As he was responsible for mission-critical data retention for the US Government, I tend to trust his judgement. :)? Link to comment Share on other sites More sharing options...
G+_Allyn Malventano Posted June 10, 2015 Share Posted June 10, 2015 Yup, but at higher capacities definitely use RAID 6 (not 5) and TLER capable drives. It also helps to treat any RAID as a disposable unit of storage - always have another 'unit' of something else as a backup. RAID is never a backup. Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 10, 2015 Share Posted June 10, 2015 Fr. Robert Ballecer, SJ I agree, it's not dead. Using it with consumer class 6TB drives isn't going to do anyone any favors. SSD is a whole other story and brings the decision tree back around to RAID 5 being preferred. Now I'm gonna have to go look up that TWiET episode, because if I remember correctly he was saying that the "RAID 5 is evil" unthinking rhetoric is wrong. Well, RAID 5 does still have a place, but not in use with 6TB spinning platters of rust. Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 11, 2015 Share Posted June 11, 2015 Just to be completely clear, at least one person has spent time in jail for professional malpractice after deploying a RAID 5 array on large capacity hard drives. Ref: http://community.spiceworks.com/topic/737958-speeding-up-nas-system-for-virtualization Link to comment Share on other sites More sharing options...
G+_Fr. Robert Ballecer, SJ Posted June 11, 2015 Share Posted June 11, 2015 That article says nothing about jail time... And it shouldn't. Bad IT design can get you sued, but it's not a criminal offense. Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 11, 2015 Share Posted June 11, 2015 To quote John773 "While I generally try not to be too harsh, this falls under "professional malpractice" to design something so bad. Amusingly the first time I ever used that phrase in relation to RAID 5 with SATA drives in a report, the person I was writing it about ended up rotting in jail for his crimes against IT..." Link to comment Share on other sites More sharing options...
G+_Fr. Robert Ballecer, SJ Posted June 16, 2015 Share Posted June 16, 2015 Travis Hershberger Sounds like hyperbole. Being an incompetent IT admin isn't a criminal offence. It's a fireable/civil offence, but can't land you in jail unless you did something criminal IN ADDITION to being a poor administrator. Link to comment Share on other sites More sharing options...
G+_Allyn Malventano Posted June 16, 2015 Share Posted June 16, 2015 A huge RAID without a backup should be a criminal offense :). Link to comment Share on other sites More sharing options...
G+_Fr. Robert Ballecer, SJ Posted June 16, 2015 Share Posted June 16, 2015 "Should be" and "is" aren't the same thing. :) Link to comment Share on other sites More sharing options...
G+_Travis Hershberger Posted June 16, 2015 Share Posted June 16, 2015 Actually.... show idea here. Why don't you try it out? Make a RAID 5 array out of the biggest capacity consumer drives you can find and purposely initialize a rebuild, see if it succeeds. It'd have to be something other than ZFS in this case because they only rebuild the used portions of the array. Link to comment Share on other sites More sharing options...
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