Just a friendly reminder on the importance of backups

[Snowmonkey]

Yes but RAID1 ISN'T a backup in any sense. I know it's arguing semantics but it is a fact.

 

Eloise

Eloise, I'm struggling to understand the difference between a drive that mirrors the original immediately and one that mirrors 5 minutes later UNLESS [you are using editing software that lacks an undo feature OR you are using software that has an undo feature AND you close the programme before you realise you made a mistake] AND you realise you have made a mistake before creating a backup.

 

(UNTIL the backup drive is removed to a different location, at which stage it assumes much greater value)

[AlainGr]

There is an aspect that has not been considered with RAID and it has to do with its compatibility between different chips, with different firmwares... They may not be compatible between themselves...

 

RAID 1 for example...

If my 2 drives enclosure fails (with the drives still ok) and I get another one, with a different RAID chip, or it could be the same RAID chip but with a different firmware, I may have to reinstall the 2 drives completely...

 

So even if the redundancy is interesting in that it reduces the downtime, depending on the type of failure, someone could loose all the data...

 

That was a serious aspect for me and helped me decide instead to have a backup strategy instead...

 

But of course, RAID and backup are not mutually exclusive. If someone also does backups and put away at least one of them in another physical location... RAID is still interesting As long as it is not considered as a backup...

[Snowmonkey]

There is an aspect that has not been considered with RAID and it has to do with its compatibility between different chips, with different firmwares... They may not be compatible between themselves...

 

RAID 1 for example...

If my 2 drives enclosure fails (with the drives still ok) and I get another one, with a different RAID chip, or it could be the same RAID chip but with a different firmware, I may have to reinstall the 2 drives completely...

 

So even if the redundancy is interesting in that it reduces the downtime, depending on the type of failure, someone could loose all the data...

 

That was a serious aspect for me and helped me decide instead to have a backup strategy instead...

 

But of course, RAID and backup are not mutually exclusive. If someone also does backups and put away at least one of them in another physical location... RAID is still interesting As long as it is not considered as a backup...

I was concerned about that, but I found that my NAS (Netgear ReadyNAS) uses the Linux Ext3/Ext4 file system, so the data is accessible on any PC by booting into Linux, in the unlikely event that becomes necessary.

 

Of course, that is more an issue with using a NAS than with RAID 1 per se.

[AlainGr]

Ah... The information I was adding was more aimed at what is called "pseudo hardware" chips and hardware chips... Of course, for what is called a "software RAID" (Linux, Windows, OS X) it makes sense that they should be handled well then

 

But maybe for the less informed persons... I would suggest Wikipedia for the search word "RAID"... They explain it a lot better than I

 

Thanks

[Audio_ELF]

Eloise, I'm struggling to understand the difference between a drive that mirrors the original immediately and one that mirrors 5 minutes later UNLESS [you are using editing software that lacks an undo feature OR you are using software that has an undo feature AND you close the programme before you realise you made a mistake] AND you realise you have made a mistake before creating a backup.

Because a backup usually keeps multiple versions for one thing a RAID never stores any older version.

 

For example if you use Time Machine as your backup solution; when you edit the metadata on a file, the new file with the new metadata is backed up at the next scheduled back up time. However if you realise you have made an error you can go back to the previous version, or the one before that.

 

That is the big difference.

 

As it is I'm pretty sure you are not advocating RAID instead of a backup; and its not about what you do ... but the advice to other people I would give is forget RAID (unless you've already bought a RAID solution) and just buy 2 additional USB drives (or a USB connected enclosure and bare drives).

 

Eloise

[Snowmonkey]

Because a backup usually keeps multiple versions for one thing a RAID never stores any older version.

 

For example if you use Time Machine as your backup solution; when you edit the metadata on a file, the new file with the new metadata is backed up at the next scheduled back up time. However if you realise you have made an error you can go back to the previous version, or the one before that.

 

That is the big difference.

 

As it is I'm pretty sure you are not advocating RAID instead of a backup; and its not about what you do ... but the advice to other people I would give is forget RAID (unless you've already bought a RAID solution) and just buy 2 additional USB drives (or a USB connected enclosure and bare drives).

 

Eloise

Ah yes, the Time Machine (and Dropbox) approach of keeping multiple old versions of files has real advantages. We actually use the NAS for my wife's Mac's Time Machine. That way, not only does she have old versions of files, she also doesn't have the risk of losing them due to disk failure.

I agree, I wouldn't bother with RAID if I didn't have a NAS - who needs extra hard drives clanking around inside a PC?

[Paul R]

I think there might be a terminology problem here.

 

A RAID system does not backup anything, unless it is used as a disk based backup for another disk, RAID, NAS, or SAN filesystem. It mirrors- which means that if you accidentally delete a file, it is also immediately deleted from the mirror. No backup, see?

 

A backup system would, regardless of the technology used, allow you to restore the file.

 

By the way, the filesystem on the RAID is pretty meaningless if younare using the RAID to best advantage, as in something like a RAID5 (6) configuration. Not only is a RAID 5 generally much faster, it also only consumes 20 to 40% of your disk space, giving you more usable disk space.

 

If you just want to use a second drive, then you are much better off to use something like Time Machine. The best choice is to use a second drive to mirror, and a third and fourth drive to backup the data periodically. Many people can fit their entire music library on one drive, and this is an excellent backup and high availability strategy for them.

 

Paul

 

 

Well any backup system "wastes" 50% of drive space, including Robocopy. The only difference with a RAID 1 setup is that it backs up immediately, instead of later. It couldn't be more easy or practical when used with a NAS. Just slip in a second drive and forget it's there. If you have a drive failure, the first you are likely to know about it is when you get an email from your NAS. Yet again, I emphasise you should still keep an off-site backup, using Robocopy or whatever else takes your fancy, so I guess you could argue you are wasting 2/3 of your drive space.

[Boris75]

Eloise, I'm struggling to understand the difference between a drive that mirrors the original immediately and one that mirrors 5 minutes later UNLESS [you are using editing software that lacks an undo feature OR you are using software that has an undo feature AND you close the programme before you realise you made a mistake] AND you realise you have made a mistake before creating a backup.

 

(UNTIL the backup drive is removed to a different location, at which stage it assumes much greater value)

 

To me, the difference is that a backup can very easily be set up to keep old versions of deleted or modified files for a certain amount of time. On a RAID disc, changes are made simultaneously to both drives, so that mistakes are hard to recover (you have to use deleted-file recovery tools etc.).

[Allan F]

On the other hand in a general sense rather than talking about particular users; a RAID array tends to lead people into complacency.

 

Very true. It gets back to the confusion about what backup really is. Redundancy and backup are not the same thing. The former does not give you the latter.

[PewterTA]

Which is why when you have 40TB... you have to double it.

 

Each 40TB is a Raid60 so that the chance of data loss is minimal on the active set of data, then duplicated for backup.

 

To keep things in sync, I just have a service set up via syncovery that as long as both are online... it'll keep the data in sync. I then keep snapshots of the data for backups off the secondary set.

 

Works out really well.

[Allan F]

I have two copied hard drives in Shanghai, two copied hard drives in Berkeley, plus one in a friend's fire-proof safe in Walnut Creek. And I do not think this is overkill.

 

Some might suggest that it is obsessive. OTOH, I suppose it provides real protection should one of the continents they are stored on disappear.

[Jud]

I've done some reading about Tarsnap now, and think I will begin using it as my backup service for music files. Some of the very smart things it does could well result in substantial cost savings versus other backup solutions: Tarsnap - Frequently Asked Questions

 

Right now you need some facility with the command line (terminal), and to use it with Windows you need cygwin.

 

It would be nice if someone wrote a graphical front end for it, though I'm pretty pleased with it as is.

[Musicophile]

I've done some reading about Tarsnap now, and think I will begin using it as my backup service for music files. Some of the very smart things it does could well result in substantial cost savings versus other backup solutions: Tarsnap - Frequently Asked Questions

 

Right now you need some facility with the command line (terminal), and to use it with Windows you need cygwin.

 

It would be nice if someone wrote a graphical front end for it, though I'm pretty pleased with it as is.

Nothing for the mathematically challenged. I've never been billed in pico- and attodollars before.

[fvf55]

I used ghost before, now aomei backupper instead, and it support backup to NAS. Do you have any ideas?

[Jud]

I've done some reading about Tarsnap now, and think I will begin using it as my backup service for music files. Some of the very smart things it does could well result in substantial cost savings versus other backup solutions: Tarsnap - Frequently Asked Questions

 

Nothing for the mathematically challenged. I've never been billed in pico- and attodollars before.

 

It works out to the same ballpark per stored GB or TB as some of the commercial solutions that have been mentioned, though the de-dupe and compression functions built into it may well result in less storage to be charged for.

[Paul R]

I just followed your link and I really like Tarsnap. Did you by any chance, dig into how stable the company is? Great technology, but if it goes away in a year or two, not worth a lot of the hassle.

 

-Paul

 

It works out to the same ballpark per stored GB or TB as some of the commercial solutions that have been mentioned, though the de-dupe and compression functions built into it may well result in less storage to be charged for.

[Allan F]

I have been using the Backup and Restore software supplied by Synology with the DS213 NAS to back up to an external USB HDD.

[Jud]

I just followed your link and I really like Tarsnap. Did you by any chance, dig into how stable the company is? Great technology, but if it goes away in a year or two, not worth a lot of the hassle.

 

-Paul

 

Paul, it's essentially a one-person deal (the software, not the storage, which is through Amazon S3). That brings advantages and disadvantages. Colin Percival, the guy behind this, is young, though of course he's subject to random chance like the rest of us humans. He doesn't have big costs, apparently, as he donates his December revenue each year to The FreeBSD Foundation. He could get tired of this at some point, but my assumption is he's a decent enough person that he'd find someone else to run things in that event.

 

On the very big plus side, the guy is brilliant, which is not a word I use lightly. While a FreeBSD committer, he took three processes that could require an hour or two (downloading code changes for the base system and ported applications, then compiling them, referred to as "make world"), and turned them into tasks that take about a minute (FreeBSD update and portsnap), vastly upgrading the security of the procedure at the same time. These processes had not changed much in a decade previous to Percival's arrival, in spite of a lot of very smart people being involved as committers, several of them later responsible for work on the guts of OS X (Jordan Hubbard, Mike Smith, Terry Lambert). In his spare time he discovered a low-level exploit for Intel CPUs that all the people responsible for security at Intel hadn't thought of.

 

Another nice thing is that he's personally available and very active in the Tarsnap forums to discuss bugs (for which he offers a bounty) and suggestions for increasing Tarsnap's functionality.