On 12/09/18 00:46, Adam Goryachev wrote: >> There are some lessons learned here, and I have decided to rethink my >> storage strategy. Not going to do RAID5 anymore, rather do RAID10 >> instead, with 4 bigger disks. That leaves one slot free in my NAS, >> which I'm going to use with a very large disk, that is as big as my >> whole RAID10 volume, and I will setup data replication between the >> RAID10 and that single disk. Not only that, I'll have another place >> where the data is also going to be synchronized, as an off-site backup. > Not a bad solution, in the past, I've done RAID10 + RAID1 with my last > really big disk, and used write-mostly for the single drive to reduce > the performance impact. RAID10 only protects you against a single drive > loss (though you might be lucky and lose two drives and still be OK). > With RAID10 + 1 you can lose any two drives, and if you are lucky, you > can lose three and survive data loss. > There are other advantages to using the 5th drive for "backups" instead > of RAID, but the disadvantage is that you will lose some data between > the last backup and current, and/or potential to "miss" some data from > the backup. Either option is valid though, just depends on your > environment and risks/needs. Any reason for not considering raid-6? That means you'll definitely survive losing two disks. And then I'd consider using all five slots for the raid, and using your large backup disk via esata or similar - if you've got a PCIe slot you're probably looking at about £50 for a card and docking bay. And then you can have two or three backup drives which can be easily rotated. (Other people might disagree with me, but if your main and backup volumes are formatted btrfs, you could use the btrfs push command to push updates the the backup disk, but I'd probably use btrfs on the backup and use snapshots and an in-place rsync. Gives me full backups for the cost of incrementals.) Cheers, Wol
