I am going to upgrade my server, taking advantage of the fact that I am going to be able to put more hard disks, I wanted to take advantage of this to give a little more security (against loss) to my data.
Currently I have 2 hard drives in ext4 with information, and wanted to buy a third (same capacity all three) and place them in raid5, so that in the future, I can put more hard drives and increase the capacity.
Due to economic issues, right now I can only buy what would be the third disk, so it is impossible for me to back up the data I currently have.
The data itself is not valuable, in case any file gets corrupted, I could download it again, however there are enough teras (20) to make downloading everything a madness.
OP has confirmed they’re 12TB each, and in total there is 19TB of data across the two drives.
Assuming there is only one partition, each one might look something like this:
Units: sectors of 1 * 512 = 512 bytes
Sector size (logical/physical): 512 bytes / 4096 bytes
I/O size (minimum/optimal): 4096 bytes / 4096 bytes
Disklabel type: gpt
Disk identifier: 12345678-9abc-def0-1234-56789abcdef0
Device Start End Sectors Size Type
/dev/sda1 2048 23437499966 23437497919 12.0T Linux filesystem
OP wants to buy a new drive (also 12TB) and make a RAID5 array without losing existing data. Kind of madness, but it is achievable. OP buys a new drive, and set it up as such:
Device Start End Sectors Size Type
/dev/sdc1 2048 3906252047 3906250000 2.0T Linux RAID
Unallocated space:
3906252048 23437500000 19531247953 10.0T
Then, OP must shrink the existing partition to something smaller, say 10TB for example, and then make use of the rest of the space as part of their RAID5 :
Device Start End Sectors Size Type
/dev/sda1 2048 19531250000 19531247953 10.0T Linux filesystem
/dev/sda2 19531250001 23437499999 3906250000 2.0T Linux RAID
Now with the 3x 2TB partitions, they can create their RAID5 initially:
Make ext4 partition on md0, copy 4TB of data (2TB from sda1 and 2TB from sdb1) into it, verify RAID5 working properly.
Once OP is happy with the data on md0, they can delete the copied data from sda1 and sdb1, shrink the filesystem there (resize2fs), expand sda2 and sdb2, expand the sdc1, and resize the raid (mdadm --grow ...)
Rinse and repeat, at the end of the process, they’d end up having all their data in the newly created md0, which is a RAID5 volume spanning across all three disks.
Hope this is clear enough and that there is no more disconnect.
You seem to be under the impression that the “buckets” in this case are all or nothing. They are talking about partitioning the drives and raiding the partitions. The way he describes slowly moving data to an ever increasing raid array would most certainly work, as it is not all or nothing. These buckets have fully separate independent chambers in them that are adjustable at will. Makes leveling them possible, just tedious and risky.
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RAID 5 is a minimum of 3 drives…I’m not sure what you mean.
deleted by creator
OP Currently has in their possession 2 drives.
OP has confirmed they’re 12TB each, and in total there is 19TB of data across the two drives.
Assuming there is only one partition, each one might look something like this:
OP wants to buy a new drive (also 12TB) and make a RAID5 array without losing existing data. Kind of madness, but it is achievable. OP buys a new drive, and set it up as such:
Then, OP must shrink the existing partition to something smaller, say 10TB for example, and then make use of the rest of the space as part of their RAID5 :
Now with the 3x 2TB partitions, they can create their RAID5 initially:
sudo mdadm --create --verbose /dev/md0 --level=5 --raid-devices=3 /dev/sda2 /dev/sdb2 /dev/sdc1Make ext4 partition on md0, copy 4TB of data (2TB from sda1 and 2TB from sdb1) into it, verify RAID5 working properly. Once OP is happy with the data on md0, they can delete the copied data from sda1 and sdb1, shrink the filesystem there (
resize2fs), expand sda2 and sdb2, expand the sdc1, and resize the raid (mdadm --grow ...)Rinse and repeat, at the end of the process, they’d end up having all their data in the newly created
md0, which is a RAID5 volume spanning across all three disks.Hope this is clear enough and that there is no more disconnect.
The number of drives doesn’t matter when you can’t copy to another. There is no replication path here.
You seem to be under the impression that the “buckets” in this case are all or nothing. They are talking about partitioning the drives and raiding the partitions. The way he describes slowly moving data to an ever increasing raid array would most certainly work, as it is not all or nothing. These buckets have fully separate independent chambers in them that are adjustable at will. Makes leveling them possible, just tedious and risky.