Mirror Linux disk writes to secondary disk

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I would like to set up a Linux system to use one primary storage device, but copy all writes to that device to another secondary device without blocking for every write - e.g. an NVMe SSD as primary and spinning rust as secondary.



The only way I can think of doing this currently would be to either run a frequent rsync in the background, or something like a btrfs-send of the live stream of disk writes.






linux raid storage software-raid







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  • Possible duplicate of Can I get SSD rw performance while keeing data security if I combine SSD & HDD in btrfs RAID1
    – Steven Davies
    9 mins ago














up vote
1
down vote

favorite












I would like to set up a Linux system to use one primary storage device, but copy all writes to that device to another secondary device without blocking for every write - e.g. an NVMe SSD as primary and spinning rust as secondary.



The only way I can think of doing this currently would be to either run a frequent rsync in the background, or something like a btrfs-send of the live stream of disk writes.






linux raid storage software-raid







share|improve this question





















  • Possible duplicate of Can I get SSD rw performance while keeing data security if I combine SSD & HDD in btrfs RAID1
    – Steven Davies
    9 mins ago












up vote
1
down vote

favorite









up vote
1
down vote

favorite











I would like to set up a Linux system to use one primary storage device, but copy all writes to that device to another secondary device without blocking for every write - e.g. an NVMe SSD as primary and spinning rust as secondary.



The only way I can think of doing this currently would be to either run a frequent rsync in the background, or something like a btrfs-send of the live stream of disk writes.






linux raid storage software-raid







share|improve this question













I would like to set up a Linux system to use one primary storage device, but copy all writes to that device to another secondary device without blocking for every write - e.g. an NVMe SSD as primary and spinning rust as secondary.



The only way I can think of doing this currently would be to either run a frequent rsync in the background, or something like a btrfs-send of the live stream of disk writes.






linux raid storage software-raid




linux raid storage software-raid






share|improve this question













share|improve this question











share|improve this question




share|improve this question










asked 25 mins ago









Steven Davies

21319




21319











  • Possible duplicate of Can I get SSD rw performance while keeing data security if I combine SSD & HDD in btrfs RAID1
    – Steven Davies
    9 mins ago
















  • Possible duplicate of Can I get SSD rw performance while keeing data security if I combine SSD & HDD in btrfs RAID1
    – Steven Davies
    9 mins ago















Possible duplicate of Can I get SSD rw performance while keeing data security if I combine SSD & HDD in btrfs RAID1
– Steven Davies
9 mins ago




Possible duplicate of Can I get SSD rw performance while keeing data security if I combine SSD & HDD in btrfs RAID1
– Steven Davies
9 mins ago










1 Answer
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up vote
3
down vote



accepted










You can use a MD RAID1 with the option --write-mostly.




subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.




I use this when I want a fast SSD but have the data on a second, spinning drive.






share|improve this answer




















  • Thanks, with that I did some more research and found the ability to use both --write-mostly and --write-behind. I'll mark my question as a duplicate of that answer.
    – Steven Davies
    12 mins ago











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1 Answer
1






active

oldest

votes








1 Answer
1






active

oldest

votes









active

oldest

votes






active

oldest

votes








up vote
3
down vote



accepted










You can use a MD RAID1 with the option --write-mostly.




subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.




I use this when I want a fast SSD but have the data on a second, spinning drive.






share|improve this answer




















  • Thanks, with that I did some more research and found the ability to use both --write-mostly and --write-behind. I'll mark my question as a duplicate of that answer.
    – Steven Davies
    12 mins ago















up vote
3
down vote



accepted










You can use a MD RAID1 with the option --write-mostly.




subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.




I use this when I want a fast SSD but have the data on a second, spinning drive.






share|improve this answer




















  • Thanks, with that I did some more research and found the ability to use both --write-mostly and --write-behind. I'll mark my question as a duplicate of that answer.
    – Steven Davies
    12 mins ago













up vote
3
down vote



accepted







up vote
3
down vote



accepted






You can use a MD RAID1 with the option --write-mostly.




subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.




I use this when I want a fast SSD but have the data on a second, spinning drive.






share|improve this answer












You can use a MD RAID1 with the option --write-mostly.




subsequent devices listed in a --build, --create, or --add command will be flagged as 'write-mostly'. This is valid for RAID1 only and means that the 'md' driver will avoid reading from these devices if at all possible. This can be useful if mirroring over a slow link.




I use this when I want a fast SSD but have the data on a second, spinning drive.







share|improve this answer












share|improve this answer



share|improve this answer










answered 21 mins ago









RalfFriedl

3,8551624




3,8551624











  • Thanks, with that I did some more research and found the ability to use both --write-mostly and --write-behind. I'll mark my question as a duplicate of that answer.
    – Steven Davies
    12 mins ago

















  • Thanks, with that I did some more research and found the ability to use both --write-mostly and --write-behind. I'll mark my question as a duplicate of that answer.
    – Steven Davies
    12 mins ago
















Thanks, with that I did some more research and found the ability to use both --write-mostly and --write-behind. I'll mark my question as a duplicate of that answer.
– Steven Davies
12 mins ago





Thanks, with that I did some more research and found the ability to use both --write-mostly and --write-behind. I'll mark my question as a duplicate of that answer.
– Steven Davies
12 mins ago


















 

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