7 ms·

Repeat after me: RAID is not a backup solution, its an uptime solution.

tjoff 6y ago
RAID is not a backup solution, its an uptime solution. I know. Doesn't change the fact there exist no sensible way to backup a decently sized pool in a home-user scenario. Now we might disagree on what is sensible. And some things might not need a backup.
- cortesoft 6y ago
  Isn’t the backup solution to always get two of whatever you build? A primary raid backed up to a second pool?
  - Cyph0n 6y ago
    Not everyone has that kind of cash lying around, especially if the pool is large and the data is not critical.
  - hedora 6y ago
    Typically three. Two local, one remote. Consider not RAID protecting the local backup.
  - dspillett 6y ago
    You need to do more than just keep a backup of current state, if you want to deal with problems other than complete failure/destruction of the primary. What about accidental deletion and incorrect editing (done too long ago for "undo" to work)?
    - xoa 6y ago
      >What about accidental deletion and incorrect editing (done too long ago for "undo" to work)? Eh? We're talking ZFS here. Built-in atomic low cost snapshots are part of the core feature set. If we're talking using a pool and backing up another pool it's a reasonable baseline assumption that one would be using either their own or one of the many mature scripts to have regular automatic snapshots and retention schedule. Ie., once every 10 min for a day, once an hour for a week or two, once a week for a year, and monthly thereafter (or whatever fits your use case), along with preservation of any manual custom snapshots. I mean, it's right there, for free.
      - dspillett 6y ago
        Fair point, but the comment I replied to did not mention configuring anything like that, and while it is all there for the taking it isn't automatically configured.
- dsr_ 6y ago
  zfs send. Keep different filesystems for system backup, personal data, media storage, gross hoarding. Consider not backing up the media storage and gross hoarding filesystems. Targets: 1. That NAS off in the corner built from an old desktop. 2. rsync.net and similar. 3. your encrypted cloud backup service of choice, through an adapter. If the value of your data is less than the cost to protect it, you know it is disposable, you just wish it weren't.
  - metalliqaz 6y ago
    Yeah as much as my daughter likes the Trolls movie, I'm not paying to back that up.
    - EvanAnderson 6y ago
      Redacted zfs send/receive in OpenZFS 2.0 might be interesting to you: https://github.com/openzfs/zfs/pull/7958 https://github.com/openzfs/zfs/pull/7958
      - metalliqaz 6y ago
        I already have selective backups to Backblaze with rclone. The point is that home users can have good reasons for relying on redundancy.
  - mnd999 6y ago
    2) and 3) requires a decent broadband upload speed. Home broadband often doesn’t provide this.
    - Fnoord 6y ago
      Depends where you're from I guess. Its also just the first backup which takes a (long) while. If you got only 10 mbit upload, then you're able to upload 600 mbit per minute, or 36000 mbit per hour. Which is about 4500 mB/hour (or ~4,4 GB/hour). Which results in 108000 mB/day (or ~105 GB/day). Its about 3/4 of a TB a week. I'm glad I got 30+ mbit upload with my VDSL2. My first backups took ages (I got 5 TB with Jottacloud). First I thought it was Duplicati being slow with regards to cryptography or being .NET, but nope that ain't it. Incremental backups during night are not going to hamper the connection though.
- hedora 6y ago
  I backup my raid array to the cloud using hyperbackup, but any incremental backup solution would work. It’s ~$60/TB/year: https://www.backblaze.com/b2/cloud-storage-pricing.html https://www.backblaze.com/b2/cloud-storage-pricing.html I only have a few TB, but the setup cost almost $1000 (it is less than half full), and it will take longer than I expect the hardware to last to spend $1000 on backups.
  - KingMachiavelli 6y ago
    If you only need backups in case of whole drive failure, AWS S3 glacier is cheaper at $0.004/GB/month. But it's still $4/month/TB or $48/TB-Year. Assuming a two 10TB drives are $300 each (actually can get them for less than $200) and last 5 years or warranty expires. ($300*2 drives /5 years / 10 TB = $12/TB-Year). So AWS glacier is still ~4x the cost of buying physical drives with RAID 1 and keeping them at a friends house. Honestly if there is any cloud storage that trades resiliency for price that would be awesome. As long as the cloud storage can tell me if any of the storage has been corrupted/lost, I'd except a 10% yearly failure rate. If my home raid is 95% and the cloud is 90% then I have an effective yearly data loss of only 0.5%.
    - res0nat0r 6y ago
      Deep Archive is my fav backup solution to just store a lot of data cheaply as there isn't really anything better, just the AWS egress charge is really the only thing they are keeping at a high price and for sure is for lock-in. .09c/GB is still too high to restore TB's of data if you need a full NAS rebuild and need to re-download everything.
- kaliszad 6y ago
  Some people mention ZFS send feature, which should prevent sending unchanged blocks. You could use rsnapshot to a different machine (that needs to be just a little bit larger than the original one) and personally I would recommend borg backup, which can deduplicate, compress and encrypt and isn't hard to setup. This could result in the backups being a fraction of the original - depending on the data. You can use AWS S3/ DO Spaces which is a lot cheaper or other compatible interfaces using rclone serve sftp + sshfs with borg or in the case of restic or duplicacy natively. You can also lookup tarsnap, rsync.net and others for remote backups. In home scenarios, you usually care about documents, pictures a few specific videos and some music above everything else. This tends to be a fraction of the total capacity. The rest doesn't change very often and is not such a loss but tends to be quite huge in comparison. So to backup all documents and pictures one or two external drives and/ or a cloud backup is sufficient. Personally, for some important documents I use orgpad.com which I help build. I am personally responsible for the infrastructure - so the backups actually have at least three tiers, independent providers etc. That is just a side effect of having a SaaS platform with a reasonable and contactable team behind it.
- tracker1 6y ago
  That said, it reduces risk of loss when an actual full backup solution is impractical... I have about 10TB of media on my current 12tb (4x4 raid5) nas box. My next plan is a 6-drive raid z2 with 8-12tb drives early next year. I can't justify doubling the cost or more to ensure it's all backed up. The important bits (to me) are in various redundant places... that doesn't mean I want to lose it and the parity options allow for some safety without too much lose of storage space.
- denkmoon 6y ago
  How can there be any sensible way other than having a complete copy of the data separate from the original copy? It can be expensive, so perhaps just prioritise what you actually need instead of backing up LATEST.MOVIE.2020.Remux.r250
  - uRStillfree 6y ago
    Yeah, this. Keep personal media metadata and download it again, maybe, but back it up? Better still, only store what you’ll watch and delete it. I only backup scans of truly useful legal documents, photos go to the cloud. Everything contemporary, disposable pop culture is “backed up” online from my perspective.
corndoge 6y ago
Nothing in gp's post even remotely indicated that they thought it was
bluGill 6y ago
False. There are too many different reasons for a backup to make that statement, and for most people RAID and NAS are combined into one. There is backup because a disks are unreliable and fail randomly. RAID is designed to solve this. There is backup because you accidentally deleted a file. There is backup because ransomware encrypted your files. RAID with snapshots solve these (arguably better than most other backup systems). There is backup because your main computers (phone) might break. NAS systems are a good place to backup these. There is backup because your house burned down [or otherwise is destroyed]. This is the only one that RAID doesn't solve. (even then you can do offsite NAS) What risks do you need to mitigate? Once you have that list you can decide what you mitigations to apply. RAID is a very useful piece of this and so saying RAID is not backup is not helpful and may harm people from making useful backups because they let the search for perfection delay them.
- djmobley 6y ago
  RAID is not a backup. It really is as simple as that, and it is helpful to remind people so they do not suffer the harms likely to result from mistakenly believing that RAID is a backup.
- Fnoord 6y ago
  If you got disks from the same brand, and same batch, chances are they will fail at the same time before a resilver.
mindslight 6y ago
This is true in a vacuum, but I feel it misses the mark having run my own personal array for 20+ years. For the most part, individuals have very little mission critical data (unless they're videographers or professional photographers). Ergo, most data on personal arrays is going to be non-critical - eg VM images, old drive images, build trees, downloaded datasets, torrented media. Does it make sense to double your cost (/halve your capacity) by backing up the whole thing, especially when the backup is likely to be more spinning rust? I've recently chosen to do so (while also backing up the critical data several different ways), but haven't always. I can understand people who still choose otherwise. Either way my main concern is a single raidz3 and I'm going to have a bad week if I lose that, independent of what can be rebuilt. In general, personal users of ZFS are very different than institutional users of ZFS. Hopefully not too divergent, so those raidz code paths still receive lots of testing and support. But you need to always keep this in mind when reading any advice about ZFS.

RAID is not a backup solution, its an uptime solution. I know. Doesn't change the fact there exist no sensible way to backup a decently sized pool in a home-user scenario. Now we might disagree on what is sensible. And some things might not need a backup.

cortesoft 6y ago
Isn’t the backup solution to always get two of whatever you build? A primary raid backed up to a second pool?
- Cyph0n 6y ago
  Not everyone has that kind of cash lying around, especially if the pool is large and the data is not critical.
- hedora 6y ago
  Typically three. Two local, one remote. Consider not RAID protecting the local backup.
- dspillett 6y ago
  You need to do more than just keep a backup of current state, if you want to deal with problems other than complete failure/destruction of the primary. What about accidental deletion and incorrect editing (done too long ago for "undo" to work)?
  - xoa 6y ago
    >What about accidental deletion and incorrect editing (done too long ago for "undo" to work)? Eh? We're talking ZFS here. Built-in atomic low cost snapshots are part of the core feature set. If we're talking using a pool and backing up another pool it's a reasonable baseline assumption that one would be using either their own or one of the many mature scripts to have regular automatic snapshots and retention schedule. Ie., once every 10 min for a day, once an hour for a week or two, once a week for a year, and monthly thereafter (or whatever fits your use case), along with preservation of any manual custom snapshots. I mean, it's right there, for free.
    - dspillett 6y ago
      Fair point, but the comment I replied to did not mention configuring anything like that, and while it is all there for the taking it isn't automatically configured.
dsr_ 6y ago
zfs send. Keep different filesystems for system backup, personal data, media storage, gross hoarding. Consider not backing up the media storage and gross hoarding filesystems. Targets: 1. That NAS off in the corner built from an old desktop. 2. rsync.net and similar. 3. your encrypted cloud backup service of choice, through an adapter. If the value of your data is less than the cost to protect it, you know it is disposable, you just wish it weren't.
- metalliqaz 6y ago
  Yeah as much as my daughter likes the Trolls movie, I'm not paying to back that up.
  - EvanAnderson 6y ago
    Redacted zfs send/receive in OpenZFS 2.0 might be interesting to you: https://github.com/openzfs/zfs/pull/7958 https://github.com/openzfs/zfs/pull/7958
    - metalliqaz 6y ago
      I already have selective backups to Backblaze with rclone. The point is that home users can have good reasons for relying on redundancy.
- mnd999 6y ago
  2) and 3) requires a decent broadband upload speed. Home broadband often doesn’t provide this.
  - Fnoord 6y ago
    Depends where you're from I guess. Its also just the first backup which takes a (long) while. If you got only 10 mbit upload, then you're able to upload 600 mbit per minute, or 36000 mbit per hour. Which is about 4500 mB/hour (or ~4,4 GB/hour). Which results in 108000 mB/day (or ~105 GB/day). Its about 3/4 of a TB a week. I'm glad I got 30+ mbit upload with my VDSL2. My first backups took ages (I got 5 TB with Jottacloud). First I thought it was Duplicati being slow with regards to cryptography or being .NET, but nope that ain't it. Incremental backups during night are not going to hamper the connection though.
hedora 6y ago
I backup my raid array to the cloud using hyperbackup, but any incremental backup solution would work. It’s ~$60/TB/year: https://www.backblaze.com/b2/cloud-storage-pricing.html https://www.backblaze.com/b2/cloud-storage-pricing.html I only have a few TB, but the setup cost almost $1000 (it is less than half full), and it will take longer than I expect the hardware to last to spend $1000 on backups.
- KingMachiavelli 6y ago
  If you only need backups in case of whole drive failure, AWS S3 glacier is cheaper at $0.004/GB/month. But it's still $4/month/TB or $48/TB-Year. Assuming a two 10TB drives are $300 each (actually can get them for less than $200) and last 5 years or warranty expires. ($300*2 drives /5 years / 10 TB = $12/TB-Year). So AWS glacier is still ~4x the cost of buying physical drives with RAID 1 and keeping them at a friends house. Honestly if there is any cloud storage that trades resiliency for price that would be awesome. As long as the cloud storage can tell me if any of the storage has been corrupted/lost, I'd except a 10% yearly failure rate. If my home raid is 95% and the cloud is 90% then I have an effective yearly data loss of only 0.5%.
  - res0nat0r 6y ago
    Deep Archive is my fav backup solution to just store a lot of data cheaply as there isn't really anything better, just the AWS egress charge is really the only thing they are keeping at a high price and for sure is for lock-in. .09c/GB is still too high to restore TB's of data if you need a full NAS rebuild and need to re-download everything.
kaliszad 6y ago
Some people mention ZFS send feature, which should prevent sending unchanged blocks. You could use rsnapshot to a different machine (that needs to be just a little bit larger than the original one) and personally I would recommend borg backup, which can deduplicate, compress and encrypt and isn't hard to setup. This could result in the backups being a fraction of the original - depending on the data. You can use AWS S3/ DO Spaces which is a lot cheaper or other compatible interfaces using rclone serve sftp + sshfs with borg or in the case of restic or duplicacy natively. You can also lookup tarsnap, rsync.net and others for remote backups. In home scenarios, you usually care about documents, pictures a few specific videos and some music above everything else. This tends to be a fraction of the total capacity. The rest doesn't change very often and is not such a loss but tends to be quite huge in comparison. So to backup all documents and pictures one or two external drives and/ or a cloud backup is sufficient. Personally, for some important documents I use orgpad.com which I help build. I am personally responsible for the infrastructure - so the backups actually have at least three tiers, independent providers etc. That is just a side effect of having a SaaS platform with a reasonable and contactable team behind it.
tracker1 6y ago
That said, it reduces risk of loss when an actual full backup solution is impractical... I have about 10TB of media on my current 12tb (4x4 raid5) nas box. My next plan is a 6-drive raid z2 with 8-12tb drives early next year. I can't justify doubling the cost or more to ensure it's all backed up. The important bits (to me) are in various redundant places... that doesn't mean I want to lose it and the parity options allow for some safety without too much lose of storage space.
denkmoon 6y ago
How can there be any sensible way other than having a complete copy of the data separate from the original copy? It can be expensive, so perhaps just prioritise what you actually need instead of backing up LATEST.MOVIE.2020.Remux.r250
- uRStillfree 6y ago
  Yeah, this. Keep personal media metadata and download it again, maybe, but back it up? Better still, only store what you’ll watch and delete it. I only backup scans of truly useful legal documents, photos go to the cloud. Everything contemporary, disposable pop culture is “backed up” online from my perspective.

corndoge 6y ago

Nothing in gp's post even remotely indicated that they thought it was

bluGill 6y ago

False. There are too many different reasons for a backup to make that statement, and for most people RAID and NAS are combined into one. There is backup because a disks are unreliable and fail randomly. RAID is designed to solve this. There is backup because you accidentally deleted a file. There is backup because ransomware encrypted your files. RAID with snapshots solve these (arguably better than most other backup systems). There is backup because your main computers (phone) might break. NAS systems are a good place to backup these. There is backup because your house burned down [or otherwise is destroyed]. This is the only one that RAID doesn't solve. (even then you can do offsite NAS) What risks do you need to mitigate? Once you have that list you can decide what you mitigations to apply. RAID is a very useful piece of this and so saying RAID is not backup is not helpful and may harm people from making useful backups because they let the search for perfection delay them.

djmobley 6y ago
RAID is not a backup. It really is as simple as that, and it is helpful to remind people so they do not suffer the harms likely to result from mistakenly believing that RAID is a backup.
Fnoord 6y ago
If you got disks from the same brand, and same batch, chances are they will fail at the same time before a resilver.

mindslight 6y ago

This is true in a vacuum, but I feel it misses the mark having run my own personal array for 20+ years. For the most part, individuals have very little mission critical data (unless they're videographers or professional photographers). Ergo, most data on personal arrays is going to be non-critical - eg VM images, old drive images, build trees, downloaded datasets, torrented media. Does it make sense to double your cost (/halve your capacity) by backing up the whole thing, especially when the backup is likely to be more spinning rust? I've recently chosen to do so (while also backing up the critical data several different ways), but haven't always. I can understand people who still choose otherwise. Either way my main concern is a single raidz3 and I'm going to have a bad week if I lose that, independent of what can be rebuilt. In general, personal users of ZFS are very different than institutional users of ZFS. Hopefully not too divergent, so those raidz code paths still receive lots of testing and support. But you need to always keep this in mind when reading any advice about ZFS.