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RAID for backup?

H

Honbe

macrumors regular
Original poster
Aug 12, 2011
151
0
Hi,

I have one OCZ SSD 240GB for Lion and Apps, second OCZ SSD 240GB for Win virtual machines and two HDDs 2TB in RAID0 for data.
I am looking for backup solution for these (currently use two FireWire external disks with SuperDuper). Do not use Time Machine as the target are two different disks. Also do not hourly backups, I just need let say daily image of the internal disks.
Would that be a good idea to install PCIe RAID card and external enclosure? Too much for this? And what software? I think I need RAID for safety in case of disk failure. Or would something like this http://eshop.macsales.com/item/Newer Technology/MXPCIE6GS2/ with external RAID SATA be enough?
Thanks in advance for help.
 
Honbe said:
Hi,

I have one OCZ SSD 240GB for Lion and Apps, second OCZ SSD 240GB for Win virtual machines and two HDDs 2TB in RAID0 for data.
I am looking for backup solution for these (currently use two FireWire external disks with SuperDuper). Do not use Time Machine as the target are two different disks. Also do not hourly backups, I just need let say daily image of the internal disks.
Would that be a good idea to install PCIe RAID card and external enclosure? Too much for this? And what software? I think I need RAID for safety in case of disk failure. Or would something like this http://eshop.macsales.com/item/Newer Technology/MXPCIE6GS2/ with external RAID SATA be enough?
Thanks in advance for help.
Click to expand...

That's merely an eSATA card...what would it attach to?

Of course, you're suggesting that you want to have an external RAID 1 (or better) for your backup drive(s) and as such, you simply don't need a super high performance SATA-III interface ... in fact, most redundancy-based RAID solutions aren't going to have a bandwidth demand much higher than a single spindle disk drive, so you're not going to see any benefit from anything better than a SATA-II speed interface...and even then, not much more than probably a 33% improvement over SATA-I or Firewire800. To have both high performance and redundancy, you'll need to run something like a RAID 10, which requires at least four (4) drives.

For an external RAID solution, I'm using the NewerTech MaxiMus system. It is a two disk stand-alone hardware RAID 1, and because the RAID is in its hardware, you can actually include a clone of your Mac's operating system and have a backup boot drive conveniently available in case your primary boot drive fails. Price-wise, they're IMO a pretty good value, particularly when you consider that you're looking at $130 versus the eSATA card you mentioned and a cheap "dumb" two drive enclosure for ($50+$40=) $90, which means that the $40 difference is buying you a hardware RAID controller.

Finally, it looks like you already have four internals, but since two of them are SSDs, you could potentially opt put them onto a bracket in your (unused?) 2nd Optical Bay and in doing so, you'll open up two 3.5" slots to put two HDDs into and make a software RAID 1 in OS X.


-hh
 
Thanks -hh for your response.

I had a look on the MaxiMus. It is an option, however I am hesitant is respect with capacity. Also - how do you connect it - FireWire? That was actually the reason I've considered the eSATa card.

I do not want to use the potential internal RAID1 made of the two HDDs as I am looking for external solution for backup.

So that these are my options:
- something external like MaxiMus with built in RAID1 (or RAID5). As said, limited capacity.
- RAID card with SAS/SATA enclosure
- NAS

Am I missing here something? Also what kind of software do you use for backup?
 
Hello,

Any type of mirroring RAID is not a back-up solution. Mirroring RAIDs are designed solely for systems that are mission critical and have to up 100% of the time. There isn't a single RAID level that is designed for back-up purposes.

Back-up solutions are simple: at least two copies, one off-site. Add more off-sites (other sites) if you're paranoid.

Back-up software: I only use Carbon Copy Cloner, and it's never let me down. You can schedule a daily (nightly) back-up if you want.

Loa
 
Honbe said:
I had a look on the MaxiMus. It is an option, however I am hesitant is respect with capacity.
Click to expand...

Any solution that you buy is going to have capacity factors - the solution there is to have stuff that's on removable drawers (which costs more), or be willing to buy more externals (also costs).

Also - how do you connect it - FireWire? That was actually the reason I've considered the eSATa card.
Click to expand...

Yes, Firewire 800. I prefer it over eSATA (fewer hassles; better reliability) and for backups, FW800 is fast enough.

While a good HDD can run slightly faster than SATA-I today (finally), the only time that you'll ever see SATA-II or -III speeds is when you have a RAID-0 type of configuration, which is an unsuitable additional risk for any sort of data backup strategy.


Loa said:
Any type of mirroring RAID is not a back-up solution. Mirroring RAIDs are designed solely for systems that are mission critical and have to up 100% of the time. There isn't a single RAID level that is designed for back-up purposes.

Back-up solutions are simple: at least two copies, one off-site. Add more off-sites (other sites) if you're paranoid.

Back-up software: I only use Carbon Copy Cloner, and it's never let me down. You can schedule a daily (nightly) back-up if you want.
Click to expand...

The main thing is to have a strategy, and to make sure that at least some of it is resistant to human errors. I use a three tier strategy:

  • Frequent - Time Machine Drive (incremental save)
  • Periodic - external RAID 1 (bulk save)
  • Periodic - NAS (incremental save)
  • Occasional - off-site copy (bulk save)

FWIW, part of the reason why I have a RAID 1 in here is because personal off-site locations typically aren't open 24/7 (eg, office at work, a bank's safety deposit box, a relative's house) and I'd prefer having my data be available 100% of the time.

The off-site copy I make with a NewerTech Voyager adaptor on a bare 3.5" drive, which then gets put back into its mylar bag and cardboard box.

Plus what's not mentioned is that the backups get periodically tested to make sure that I don't have something that I think is good (but isn't).

Finally, using a "Cloud" storage site could be another potential backup alternative, but transfer speeds and potential bandwidth caps are factors to consider, particularly when one's amount of data grows.


-hh
 
-hh: your infos are very valuable, thank you. I am getting closer, however I have one more question to you, if I may: what would be (in your opinion) a better solution for backup:
- FW800 enclosure with HW RAID1 (can agree FW800 is enough for backups) or
- LAN NAS with RAID1

I have already off site and cloud backups in place and do not really need frequent incremental backups like Time Machine (which did not worked that well for me in the past anyway).

Honbe
 
-hh said:
FWIW, part of the reason why I have a RAID 1...
Click to expand...

The fact that your back-up is off site or not, available 24/7 or not, has nothing to do with choosing a RAID. RAID 1 as a back-up just doesn't make any sense: you gain absolutely nothing by having a mirror of your back-up in the same physical location. If you have 2 drives (to make your RAID1), you're a lot better having those 2 drives in different locations.

Loa
 
Loa said:
The fact that your back-up is off site or not, available 24/7 or not, has nothing to do with choosing a RAID. RAID 1 as a back-up just doesn't make any sense: you gain absolutely nothing by having a mirror of your back-up in the same physical location. If you have 2 drives (to make your RAID1), you're a lot better having those 2 drives in different locations.

Loa
Click to expand...

In my opinion RAID1, even for backup, makes sense. It protects against HW failure, which as we know, happens. Of course, it is not a substitution for off site backup (having backups in different locations).

Honbe
 
Honbe said:
It protects against HW failure
Click to expand...

No it does not. Think about it this way:

Imagine you have a RAID1 of some back-up, and one drive fails. You're left with one copy of your data.

Imagine you have 2 copies of your back-up, in two different locations, and one drive fails. You're left with one copy of your data.

What did you gain by having a RAID1? **Nothing**.

By storing your 2 drives in different locations you only gain protection compared to having them in 1 location, as you're forced to with a RAID1.

Simple. RAID1 is not a back-up solution at all.

Loa
 
Loa,

thanks for response. Now imagine you have RAID1 backup in one location AND another backup in another location. When one of the RAID disks fails, you still have TWO backups, one of which directly on hand. Am I right?

Now if you have just two copies in two different and one of them fails, well, you have just one backup. In case the one on site fails, you depend on the off site one out of reach at that moment.

Honbe
 
Honbe said:
Now imagine you have RAID1 backup in one location AND another backup in another location
...

When one of the RAID disks fails, you still have TWO backups
Click to expand...

The principle stays the same. You seem to fail to realize that a RAID1 is *two* drives in the same place. In your scenario, with a RAID1 + another back-up, that means 3 drives.

For me, 3 drives = three locations. If one fails, I still have 2 copies, just like in your scenario.

The advantage of having those 3 drives in 3 different locations is that if one is flooded, burned, destroyed, stolen, you still have 2 other copies. If your RAID1 gets flooded, burned, etc, you just lost 2 drives in a single swoop.

Still simple: never RAID1 for back-up.

Loa
 
Honbe said:
Now imagine you have RAID1 backup in one location AND another backup in another location. When one of the RAID disks fails, you still have TWO backups, one of which directly on hand. Am I right?
Click to expand...

Yes. The 2nd drive would have your data onsite and your offsite backup would still be there unless ghosts get it. Then rebuild your RAID.
RAID1 is not so much backup as failure protection in my book.
 
derbothaus said:
Yes. The 2nd drive would have your data onsite and your offsite backup would still be there unless ghosts get it. Then rebuild your RAID.
RAID1 is not so much backup as failure protection in my book.
Click to expand...

That is what I mean. More like another layer of (failure) protection within a backup solution.

Honbe
 
Honbe said:
That is what I mean. More like another layer of (failure) protection within a backup solution.

Honbe
Click to expand...

If you want it like that do it. Disk Utility can get you up and running. If you don't like it break the RAID and do something else.
 
Hello,

Look, if you wanna waste 1 drive in a RAID1 set-up, go ahead. But if you think it through correctly, you have less protection than if you spread that extra drive to another off-site location.

The only way a RAID1 onsite back-up can help is if your main system fails at the same exact time one of the drives in the back-up RAID1 fails. Since drive failure rates are measured in years, what are the chances of that ever happening...

While you're at it, protect yourself from meteor strikes, alien invasions, spontaneous combustions, etc... :p

Loa
 
Loa said:
Hello,

Look, if you wanna waste 1 drive in a RAID1 set-up, go ahead. But if you think it through correctly, you have less protection than if you spread that extra drive to another off-site location.

The only way a RAID1 onsite back-up can help is if your main system fails at the same exact time one of the drives in the back-up RAID1 fails. Since drive failure rates are measured in years, what are the chances of that ever happening...

Loa
Click to expand...

Right, you want raid1 on your primary data drive, not necessarily on backup. I'd second the need for offsite backup.
 
RAID 1 wasn't designed as a backup, but to keep a system running if a disk fails, such as the OS.

This is known as availability, as you don't want a server going down if at all possible (so in the case of a RAID 1, if one disk dies, it's still operational). Just stuff in a new disk, and the system rebuilds the data on the replacement disk.

Now RAID can be used as a backup solution, but not as replacement of a backup solution (i.e. primary data on a RAID, and the backup is a separate RAID as the primary on-site backup location).
 
The more I think about it the more the RAID1 for backup seems unnecessary. It would only make sense in case TWO disks will fail at the SAME time.

I think I will go with something like SansDigital Towerstor TS5CT - 5 bay hot swap enclosure configured as JBOD for maximum capacity, connected via FW800. It still can be configured as RAID1 (or 3,5,10) if really needed later. I know it is a little pricey, but will give space for the future. Or do you have better idea?

Thank you

Honbe
 
Honbe said:
I think I will go with something like SansDigital Towerstor TS5CT - 5 bay hot swap enclosure configured as JBOD for maximum capacity, connected via FW800. It still can be configured as RAID1 (or 3,5,10) if really needed later. I know it is a little pricey, but will give space for the future. Or do you have better idea?

Thank you

Honbe
Click to expand...
FYI
Looks like Newegg has it on sale? Here
 
I may also go with Areca ARC 1880-LP and SansDigital TowerRAID TR4X. It would be about $200 more than TS5CT and really future proof. I am getting confused...
Which will be better for true JBOD implementation for backup (separate drives)? I've seen threads stating problems with JBOD and FW800.
 
Honbe said:
I may also go with Areca ARC 1880-LP and SansDigital TowerRAID TR4X. It would be about $200 more than TS5CT and really future proof. I am getting confused...
Which will be better for true JBOD implementation for backup (separate drives)? I've seen threads stating problems with JBOD and FW800.
Click to expand...
You must use enterprise disks with hardware RAID controllers for stability reasons (card is in total control of the disks, so the drive firmware is different from the consumer counterparts), which will make the cost difference much higher than just $200.

This is why they create the HDD Compatibility List (.pdf file) in the first place; it saves users all kinds of headaches by giving a list of verified drives that operate correctly with their products
 
OK, I've ordered SansDigital TR4M with eSATA card bundle. Will configure as JBOD with WD Caviar Greens for backup.
Thank you all again for opinions.

Honbe
 
BTW, the above is bundled with RocketRAID 622 controller. Is this one compatible with OSX / Lion?
 
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