4 ms·

What's are the usecases of a filesystem like that? I can't think of a situation where I care that my data is mirrored, but I'm okay with losing 5 minutes of it.

by dymk 3y ago

londons_explore 3y ago
Your home desktop PC? I'd be perfectly fine losing 5 minutes of data in case of a disk failure. After all - I can probably recreate it in about 5 minutes. Anyone who does daily backups is effectively saying "I care about my data, but I'm happy to lose up to a days worth if there is a failure".
- dymk 3y ago
  I suppose I would just throw another SSD in there and mirror with RAID1 (or equivalent), and save myself the headache. SSDs are cheap - A Samsung 980 1TB is $50. Edit: I think you can achieve what you want with current tools, or something pretty close at least, with ZFS. Create a snapshot of your SSD pool every 5 minutes, then stream the delta to an HDD pool in an automated fashion. Delete snapshots more than X hours / days old.
  - catiopatio 3y ago
    This is exactly how my desktop PC is setup. I use the HDD ZFS pool to maintain effectively infinite non-expiring snapshots of my (single device) SSD ZFS pool. If my SSD fails, I can boot directly from the latest backup on the HDD pool.
  - mat_epice 3y ago
    From what I understand, cheap SSDs behave very badly under RAID. For example, Synology actively discourages Samsung EVO SSDs because they cause timeout issues.
  - jlokier 3y ago
    One of the reasons they say "RAID is not backup" is because the kinds of things that take out a single drive, take out multiple drives together often enough that it surprises people. I've seen more than one person report that they had a RAID NAS at home, thinking their data was safe, only to be horrified one day that every drive failed the same day. An electrical surge from a lightning strike or a faulty power supply, for example, can fry all the drives at once.

What's are the usecases of a filesystem like that? I can't think of a situation where I care that my data is mirrored, but I'm okay with losing 5 minutes of it.

by dymk 3y ago

What's are the usecases of a filesystem like that? I can't think of a situation where I care that my data is mirrored, but I'm okay with losing 5 minutes of it.

londons_explore 3y ago

Your home desktop PC? I'd be perfectly fine losing 5 minutes of data in case of a disk failure. After all - I can probably recreate it in about 5 minutes. Anyone who does daily backups is effectively saying "I care about my data, but I'm happy to lose up to a days worth if there is a failure".

dymk 3y ago
I suppose I would just throw another SSD in there and mirror with RAID1 (or equivalent), and save myself the headache. SSDs are cheap - A Samsung 980 1TB is $50. Edit: I think you can achieve what you want with current tools, or something pretty close at least, with ZFS. Create a snapshot of your SSD pool every 5 minutes, then stream the delta to an HDD pool in an automated fashion. Delete snapshots more than X hours / days old.
- catiopatio 3y ago
  This is exactly how my desktop PC is setup. I use the HDD ZFS pool to maintain effectively infinite non-expiring snapshots of my (single device) SSD ZFS pool. If my SSD fails, I can boot directly from the latest backup on the HDD pool.
- mat_epice 3y ago
  From what I understand, cheap SSDs behave very badly under RAID. For example, Synology actively discourages Samsung EVO SSDs because they cause timeout issues.
- jlokier 3y ago
  One of the reasons they say "RAID is not backup" is because the kinds of things that take out a single drive, take out multiple drives together often enough that it surprises people. I've seen more than one person report that they had a RAID NAS at home, thinking their data was safe, only to be horrified one day that every drive failed the same day. An electrical surge from a lightning strike or a faulty power supply, for example, can fry all the drives at once.