Phenix51 Posted January 31, 2019 Share Posted January 31, 2019 I have a Cisco UCS 240M3 that hasn't been using in a couple years and I would really like to start utilizing this box since it has dual 10core CPUs with 128GB of RAM. it has 24 2.5" drive bays. My question is: how many parity drives would I realistically need assuming I would be utilizing all 5TB 2.5" drives in each slot(minus the two slots I plan on using for Cache)? I'm completely new to UnRaid and just don't want to make any assumptions. Realistically, I'll only be filling 6-8 drive bays initially with 5TB drives and just two 1-2TB SSDs for caching. Quote Link to comment
whipdancer Posted January 31, 2019 Share Posted January 31, 2019 Unraid supports up to 2 parity drives (that allows you to lose up to 2 drives before things get really ugly). Whether you use 0, 1 or 2 parity drives is really based on your tolerance for losing data. I use 2 parity drives because the outlay to have 2 is worth the security of being more likely to recover from a lost drive - to me. Quote Link to comment
trurl Posted January 31, 2019 Share Posted January 31, 2019 With that drive count I would definitely recommend dual parity. Quote Link to comment
Phenix51 Posted January 31, 2019 Author Share Posted January 31, 2019 41 minutes ago, whipdancer said: Unraid supports up to 2 parity drives (that allows you to lose up to 2 drives before things get really ugly). Whether you use 0, 1 or 2 parity drives is really based on your tolerance for losing data. I use 2 parity drives because the outlay to have 2 is worth the security of being more likely to recover from a lost drive - to me. Ah, understood. I still can't help but think in terms of a traditional RAID array and just really don't want to make any assumptions. I definitely plan on having two drives for parity, just wasn't sure I had say sixteen 5TB drives on this unit if I would need a certain number of drives to ensure fault tolerance. Thanks for the clarification, it is appreciated. Quote Link to comment
Squid Posted January 31, 2019 Share Posted January 31, 2019 15 minutes ago, Phenix51 said: if I would need a certain number of drives to ensure fault tolerance. The one key thing with unRaid vs "traditional RAID systems" is that on a traditional RAID, if you exceed your fault tolerance, you've lost everything, 100% gone, sorry about your luck. unRaid, you will only ever lose a fraction under the same circumstances. (Assuming of course that the cause of the fault wasn't that a stampede of wild elephants decided that your server room made a good place to have some fun in - in which case at least you have a good story to tell) Quote Link to comment
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