December 19, 20169 yr Currently I have a cache pool of 4 drives and would like to clarify as to the extend of disk failures I can survive. I currently have a drive that is increasing in Reallocated sector counts. I'm sure that I could pull this drive and be fine however if another drive were to start failing would I lose disk space,data or do i just lose protection at that point? My assumption is that I could lose 2 drives and keep all my data and 480GB pool size but then I would lose redundancy. Is this a correct assumption? Below is my cache pool information: btrfs filesystem show: Label: none uuid: 51aa87ad-1a53-4d13-8ab8-58d953785aaf Total devices 4 FS bytes used 189.30GiB devid 1 size 223.57GiB used 175.00GiB path /dev/sdk1 devid 2 size 223.57GiB used 175.00GiB path /dev/sdi1 devid 3 size 223.57GiB used 175.03GiB path /dev/sdj1 devid 4 size 223.57GiB used 175.03GiB path /dev/sdl1 btrfs filesystem df: Data, RAID1: total=349.00GiB, used=188.84GiB System, RAID1: total=32.00MiB, used=64.00KiB Metadata, RAID1: total=1.00GiB, used=471.27MiB GlobalReserve, single: total=160.00MiB, used=0.00B
December 19, 20169 yr Community Expert If 2 drives fail at the same time you can loose data, if there's one failure and then another one after the pool had time to rebalance you will be fine.
December 20, 20169 yr Author If 2 drives fail at the same time you can loose data, if there's one failure and then another one after the pool had time to rebalance you will be fine. Thanks for that information. Quick question, when the pool rebalances, do you know how it would affect my pool size? Would it decrease to 360gb?
December 24, 20169 yr Author Yes. Thanks Johnny. Also would I need to stop the array to pop out the cache drive for it to rebalance or can I just removed the drive anytime?
December 24, 20169 yr Community Expert The preferred way is tho follow the procedure on the FAQ, but you can also remove one device and start the array and a balance should start (device has to be physically disconnected from the server or wiped, or else you'll get an umnountable pool).
December 24, 20169 yr Author The preferred way is tho follow the procedure on the FAQ, but you can also remove one device and start the array and a balance should start (device has to be physically disconnected from the server or wiped, or else you'll get an umnountable pool). Thank you for all your help. I've bookmarked that link.
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