|Feb 14, 2013, 09:27 PM||#1|
Backups - Just tell me what to do
First off, yes, I've searched for this, read up on this, and spent months messing around with this. I simply can't get it right. So I'm asking for your opinion. Just tell me what to do.
Backup my Mac Pro on 2 pairs of rotating disk sets. Each set consists of four 3 TB SATA drives. One set is here being backed up with Carbon Copy Cloner every night, and the other set goes to my parents house. I switch them once a month.
The Mac's Data:
0.3 TB (SSD Boot drive)
1.9 TB (a USB drive)
3.4 TB (a RAID)
5.4 TB (a RAID)
TOTAL = 11 TB of data spread over 4 drives
Failed Attempt 1:
I used to use a 4 bay drobo. Besides not being large enough due to its algorithm (I excluded stuff from the backup to make it work) it was also SLOW as hell. 700 MB would take over 20 hours to backup, which means that it often hadn't finished last night's backup when the next day's wanted to start.
Besides that rather glaring flaw, I also didn't like that if the Drobo broke I'd be unable to access my backups without buying another one. So I set out to fix both problems.
Failed Attempt 2:
I bought an OWC Mercury Elite Pro Qx2 which will give me all 12 GB of the space on my drives for backup, and I can set it to "span" instead of "stripe." I was under the impression that spans were different from RAID 0 stripes. I thought the advantage of spanning was that I could read data off any disk even if the others failed.
But I was wrong, spanning is just like RAID 0, only slower. It doesn't offer the speed advantage, nor can I access a drive by itself. So if one drive fails, the other 3 are trash too. I wanted to avoid that, but it doesn't look like the OWC MEP has the ability to do anything like that. I'm not sure why it has a "Span" setting when it's the same as the RAID 0 setting, but it does offer both. (Plus every other kind of RAID you can imagine, but they all either take away space or marry my drives so that one failure takes the all out.)
It also can not do JBOD.
- - - - - - -
So here are my options as I see them:
1) Stick with this current spanning RAID, ignore the fact that I'm essentially using a RAID 0 by another name, and just take comfort in the fact that I have 2 complete backups. What are the odds that they'll both fail at the same time? (Problem: I was being sarcastic just then, this makes me nervous.)
2) Find out from you about some magical array that does spanning in a way where I can read individual disks by themselves, like I originally thought it would. (Would be great, but I'm suspecting this is just a dream. Rats.)
3) Get an enclosure that will let me run my disks as JBOD style. If so, what hardware do you suggest? (Drawback...it'll be a pain in the ass to manually set up auto-backups for my 3.4 TB and 5.4 TB drives to back up to my smaller backup disks that are just 3 TB. But hey, what's tech-work but constant pains in the ass?)
4) Get 4 USB enclosures and...holy hell, at this point why don't I just buy external drives? I sure hope it doesn't come to this.
Thanks in advance. I lost a lot of data last spring when a drive failed on the same exact same weekend the Drobo was being bitchy and was being re-formatted. I had always been pretty good with backups in general and so that timing really frustrated me. I'm looking to go beyond "pretty good" into "darn near foolproof."
I don't think I'm there yet.
|Feb 15, 2013, 06:51 PM||#2|
The NRAID option on the Qx2 looks like it's a JBOD. If that's so, I'd select it.
Otherwise, I got a pair of 4bay enclosures (Sans Digital, eSATA), and use them as you do (one for regular back-up, the other on a weekly rotation with the first at my parent's house), and it works great.
Look for simple solutions (like the ~100$ enclosures), and don't worry too much with RAID0 fail rates. They're still dramatically low and that's why you have 2 back-ups.
Not sure why such a simple solution wouldn't work for you.
|Feb 15, 2013, 08:37 PM||#3|
You have 4 different volumes to back-up. One problem is trying to dump all of that into one new volume and/or disk enclosure. The first two are quite small and came be consolidated onto one 3TB drive with room to spare. The second two can each be covered by a 3TB pair.
These 4 volumes should have quite different rates of change. I'd guess that 5.4TB is mostly unchanging media which change rate is actualy quite same but in relatively large individual chunks.
If not doing staggered back-ups then it is likely one reason the times are slow is because had multiple competing back-ups. For example, two back-up streams running concurrently over FW800 and eSATA will get more done is a fixed amount of time than just leveraging one of those two.
Other issue is that if keeping an archiving back-up ( alternative and deleted files over time) then you'll need back-up targets larger than your source drivers. Again separating things out should help to target you solutions more carefully. 20% more for the first two are quite different than 20% more for the last one. Again commercial media files tend not to change over time.
So something like
with one 3TB and one 4TB drive could do back-ups for #1 -#2 combo and #3 . The major point being is that you don't need RAID to solve these three back-ups.
and a second enclosure
this one with two 3TB drives. for #4.
[you could duplicate this enclosure to set up a RAID-10 by mirroring with software RAID-1 if concerned about a single disk failure in back-up. Frankly commericial media probably can be gotten from somewhere else anyway or vast bulk from offsite back-up. Unless this is some dynamic data, the redundancy of the offsite back-up more cost effectively solves the issue of back-up of the back-up. ]
the first leverages two eSATA connectors. The second could be plugged into FW800. You'll get concurrent throughput with minimal interference for "overnight jobs".
Buy another set in the same two configurations and can rotate them to the remote site.
The first full copy back-up should be quite painful. Especially, since have to do it twice to pre-seed the offsite. But after that if leveraging the incremental of CCC it should be as long a process on a nightly basis.
Last edited by deconstruct60; Feb 15, 2013 at 08:46 PM.
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