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nMP, External Storage and Backup (NAS? RAID?)
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NAS RAID is the issue. There are plenty of forum discussion on this topic all over the net and even here.
NAS RAID only covers (other than "striped drives") hard drive failures and not other types of failures within itself. This is why many don't consider it a viable back up solution. Often with lower end NAS RAIDS (usually RAID 5 or 6), rebuilds don't always work when a drive fails and also, the dependency on yet another OS added to the equation requiring if the unit it self fails, more likely having to purchase from the same maker the same or similar model NAS unit to get your data back.
I have stated I have two NAS units (RAID 5 btw) and consider for what I store on them - as being acceptable risks.
Data recovery with the various brands of NAS can be troublesome, I have pulled a few invisible hairs out. Linux boot disks, mounting volumes, new firmware trashing things - a pita!
Hence why I use a modded HP ex490 server/server 2012 essentials with 4 drive bays and another four in a port multiplier raid enclosure. Server 2012 essentials can be setup in workgroup instead of domain mode bypassing any active directory shenanigans which for most non office corporate and especially Mac users is unnecessary and too complicated. Simple backup media server & storage system that I trust and can be easily fixed if it goes wrong. Mac clients of mine use them, the console to manage them is very easy to understand and if they can do it well anyone can!
Can easily mount a storage space for TM backups over the LAN also..
Yes I know it's (spit) Microsoft but their server stuff is a different ball game to a client OS!
Hence why I use a modded HP ex490 server/server 2012 essentials with 4 drive bays and another four in a port multiplier raid enclosure. Server 2012 essentials can be setup in workgroup instead of domain mode bypassing any active directory shenanigans which for most non office corporate and especially Mac users is unnecessary and too complicated. Simple backup media server & storage system that I trust and can be easily fixed if it goes wrong. Mac clients of mine use them, the console to manage them is very easy to understand and if they can do it well anyone can!
Can easily mount a storage space for TM backups over the LAN also..
Yes I know it's (spit) Microsoft but their server stuff is a different ball game to a client OS!
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I can't be the only person who'd like to hear more about the ways in which it's wonderful.
RAID by itself isn't a backup solution, it's a method of ensuring data is available after a disk failure in most cases. If you have RAID on a NAS and use this as a time machine server, for example, this is backup. Time machine is providing the backup, not RAID. You could have a USB disk attached and just copy files to it. This would also be backup.
If you have only one copy of the data on the same NAS, the RAID itself doesn't provide a backup. If you delete a file it's gone. There is no second copy. If you lose a disk in the NAS the data will still be there however, this is what RAID does.
Does that make sense?
Everything you mentioned above have equivalents when it comes to DAS RAID devices. The enclosure could fail, leaving you in the same position as if your NAS died. Buy a cheap hardware RAID enclosure, and you get what you pay for.
There are certainly NAS devices out there that are as reliable, if not more reliable, than many DAS options. You do have a different OS in the mix, but most of the time that is Linux, which is a widespread OS with lots of support.
I'm not saying that NAS is better than DAS for backup. I just don't see why NAS has any technical disadvantage as a Time Machine volume.
shaunp said:
I think we are talking about different things here. I agree that RAID isn't backup. My question was addressing whether using Time Machine with a NAS RAID is any less reliable than using a DAS RAID as a backup volume.
What you say is partially correct (your response directed towards me)...however, here is what matters
- NAS - separate operating system, either hardware of software RAID. Unless you are able to master the above when things go wrong it can go really wrong.
- DAS - if it has built in RAID, you are at the mercy of how the RAID is done or can be undone.
- DAS - fully controlled by your computer's OS or an application has the most control over the files stored. Included in this group are simple external drives that you back up to without RAID.
I have two NAS units - QNAP which consists of 5 x 4tb and 4 x 3tb. I have certain directories that are rsynched between them to keep important data on both and the process isn't always perfect but so far so good. I also have simple single external (DAS) drives with the same data and serve as the real back ups.
If you feel comfortable using NAS as your back up, then it is what it is. Any other person that is dealing with higher end NAS will most likely tell you the same thing - NAS RAID is not a safe back up.
I've got four 256 SSD's in there, and it's on the end of a 30 ft Corning TB optical cable back in a cabinet. So it's low power, low noise (silent to me practically at around 10 dB at best), fast (500 MB/s read and write), and otherwise just works perfectly. The device sleeps and wakes up with my computer and I can otherwise forget it, it's just like having that storage internally.
Anyone used these before? It's a DAS right?
OWC Mercury Elite Pro Qx2
Something odd regarding the spec:
OWC Mercury Elite Pro Qx2
Something odd regarding the spec:
Lots of information
Lots of information being tossed out here. All of it is informative. I think, however, that the OPs original search for a solution has not been resolved. Or maybe it has.
For me the discussion seems to mix up this way of combining multiple disks in a RAID functionality in a box that is either a DAS or a NAS. Both DAS and NAS can have multiple RAID options. And RAID has a bunch of variations (0, 1, 5, 6,...). So that seems to be one question.
The bigger question is expectation for this box. Is it going to act as a mostly realtime data vault for use as a place to read and write working data throughout the day? Are multiple users going to need to access it throughout the day? Or is it going to be used as a relatively static repository/backup of all of those different current volumes once a week, day, hour?
These questions ought to be answered early on in this decision process because they will help to guide you to the final decision.
It seems that many people who have home networks use a NAS just like a file server at the office. It's the place that maintains your live data throughout the day and gets backed up to another device at regular intervals.
Yet, if your primary function is to use the four different disks attached to your MP and then you want a place to back those up in a scheduled manner and networking is not of importance to you, then a DAS should satisfy your needs.
One of the bottom lines here is that whatever unit is your working space throughout the day should have a scheduled backup to another unit on a regular basis.
Lots of information being tossed out here. All of it is informative. I think, however, that the OPs original search for a solution has not been resolved. Or maybe it has.
For me the discussion seems to mix up this way of combining multiple disks in a RAID functionality in a box that is either a DAS or a NAS. Both DAS and NAS can have multiple RAID options. And RAID has a bunch of variations (0, 1, 5, 6,...). So that seems to be one question.
The bigger question is expectation for this box. Is it going to act as a mostly realtime data vault for use as a place to read and write working data throughout the day? Are multiple users going to need to access it throughout the day? Or is it going to be used as a relatively static repository/backup of all of those different current volumes once a week, day, hour?
These questions ought to be answered early on in this decision process because they will help to guide you to the final decision.
It seems that many people who have home networks use a NAS just like a file server at the office. It's the place that maintains your live data throughout the day and gets backed up to another device at regular intervals.
Yet, if your primary function is to use the four different disks attached to your MP and then you want a place to back those up in a scheduled manner and networking is not of importance to you, then a DAS should satisfy your needs.
One of the bottom lines here is that whatever unit is your working space throughout the day should have a scheduled backup to another unit on a regular basis.
So why can't we have both? A DAS that is also a NAS? getting the max speed at home from the hard drives and still being able to access files at a slower speed on the move
I'm guessing there is a reason for this, If anyone could explain I would appreciate it.
In the past, there was a way to somewhat do this - have two machines with their own OS talk to the same drive. This was what SCSI drives were all about but this never took off in a mainstream way.
What you have to realize that a NAS has its own operating system that has to be responsible for the drives within. DAS is a "dumb" drive or set of drives that simply responds to your computer's commands when attached. There is no clean way to arbitrate a drive from two "masters." Another notion that gained popularity but was better on paper than real speed in reality (yes many NAS now offer it) is iSCSI. You should research iSCSI and see if perhaps this might be the only compromise that resembles what you are asking for.
I think for fast access and control - DAS is the way to go. I use two NAS units at home and various external drive solutions for my Mac. They all serve different purposes. DAS is great for speed and control and NAS is good for bulk storage that is shared by other devices.
My work files and the like are on my external drives and also a copy on the NAS units. The NAS in general hold my media files and second copies of work files (mostly photo related).
As Thunderbolt is starting to (finally) take off with almost reasonable prices, DAS multi-drive would be what I think would suit most people's needs.
If you are looking for a mega-store DAS, you may want something like this - http://www.barefeats.com/hard167.html by Areca. Btw Bare feats is a good site to see all sorts of options on hardware (along with tests and comparisons).
Well I'm happy with those extra informations and I'm pretty sure I'm looking for a DAS
Nope, it'll be used to backup my 4 external drives, I'll be the only user and I'm planning to make it a habit to back up once a day.
Yeah, I'm only looking for a place to back up my hard drives, I didn't even know of the existence of DAS as people usually only speak of NAS.
Agreed, as I don't have any backup solution right now and I don't want to have to attached 8 hard drives (4 main working + 4 backup) to my computer each time, would prefer for the backup to have a 4 bay enclosure with only 1 USB 3 to be connected to my nMP (Thunderbolt solution is above my budget for now and I'm only using it for backup, so don't think I'll need the speed thunderbolt provides)
Any suggestions for a USB 3 DAS enclosure? I posted a suggestion a few post earlier about OWC Mercury Elite Pro Qx2, any idea bout this enclosure?
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It's cheaper because there's no raid function
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[Any suggestions for a USB 3 DAS enclosure? I posted a suggestion a few post earlier about OWC Mercury Elite Pro Qx2, any idea bout this enclosure?[/QUOTE]
i have an older [2010] Qx2 that is attached to a Lacie eSata Hub then Thunderbolt to my nMP. The new ones have more options.
For example:
1. USB3
2. JBOD
3. Large capacity [3 or 4TB drives, mine has a 2TB per bay limit]
That said, i can talk about my experience. been running 24/7 since 2010 with no issues. Has acted as first a backup iTunes 4TB library and now a live 4TB iTunes Library. No issues. And I recently had a question about JBOD and couldn't find my manual from 2010, called support and they took the time to answer me, no issues about it being 4 yrs ago. I've seen some folks in this forum not liking the Qx2 but I've had no issues and I am getting USB3 speeds [eSata limits Thunderbolt bandwidth].
i have an older [2010] Qx2 that is attached to a Lacie eSata Hub then Thunderbolt to my nMP. The new ones have more options.
For example:
1. USB3
2. JBOD
3. Large capacity [3 or 4TB drives, mine has a 2TB per bay limit]
That said, i can talk about my experience. been running 24/7 since 2010 with no issues. Has acted as first a backup iTunes 4TB library and now a live 4TB iTunes Library. No issues. And I recently had a question about JBOD and couldn't find my manual from 2010, called support and they took the time to answer me, no issues about it being 4 yrs ago. I've seen some folks in this forum not liking the Qx2 but I've had no issues and I am getting USB3 speeds [eSata limits Thunderbolt bandwidth].