Advice on external backup of a Linux server.

[Arthur Pemberton]

Bill Gradwohl wrote:

> Arthur Pemberton wrote:
>
>> However I'm planning this for a smal business. As I'm sure you're 
>> aware normal employees (ie. non geek, or computer centric) shouldnt' 
>> really be trusted with anything computer, so if possible, I woudl 
>> prefer not to rely on them to switch on the USB HDD to allow it to 
>> backup.
>
>
> In a business situation, you have to answer the question: "Am I going 
> to take a true disaster into consideration or not?"
>
> Since 1982, we've seen only 1 real disaster. A twister that rolled 
> thru downtown Ft. Worth and did lots of damage. One of the larger 
> building was so heavily damaged that it was condemned by the city. A 
> client of ours in that building had their office space so completely 
> trashed, we couldn't identify where we were when we hit their floor. 
> The interior walls were gone, exterior windows blown out, etc. We 
> found a users area where the monitor was sucked out the window, 
> severing the cable to the computer. The computer however worked just 
> fine when we retrieved it from under the desk and gave it a new monitor.
>
> Their server room was drenched in water with soaked ceiling tiles and 
> insulation all over the equipment.. We physically moved the gear to a 
> new site a few miles away, opened up and dried off everything, plugged 
> things in and they were up. Not one computer was lost.
>
> Now, when someone says that you HAVE to consider disaster recovery, 
> I'm no longer in complete agreement. Its up to you. If you want off 
> site backup fine. If not, that's fine too.
>
> We don't think software RAID is a good idea. We prefer real hardware 
> RAID. RAIDing a server does not provide disaster recovery protection. 
> If the box burns, gets flooded, stolen, etc, its ALL gone. RAID isn't 
> even good for "oops" recovery. When someone creates an "oops" mini 
> disaster by erasing the payroll master file, its still gone even with 
> a RAID array.
>
> In our experience, "oops" mini disasters occur all the time. They are 
> the ones you need to protect against. Having a spinning "snapshot" 
> backup on disk is the way to go. We set them up to snapshot the 
> servers main drive or drive array(s) every hour during working hours, 
> and once over night. Should someone destroy a file, the admin can 
> reach into the latest snapshot and retrieve it, or the generation from 
> an hour ago, or the one from 3 hours ago, or the one for 3PM last 
> Thursday, etc. That's the flexibility a business needs. If the latest 
> upgrade to the accounting system software turns out to be problematic, 
> we can roll it back by grabbing a generation of the environment from 
> before the upgrade. These are the common problems that backup can 
> handle well and occur routinely in any business environment.
>
> Most small business users can't properly handle restores from tape, or 
> even consistently feed the machine a new tape daily. Therefore, we 
> gave up on tape a few years ago. Any "admin" can use their Windows 
> Explorer to hit the snapshot area and retrieve a file with a few mouse 
> clicks. Note that only the admin and the business owners are given 
> access rights to the snapshot area. Internal drives are perfect for 
> this, and require no manual intervention. If a site has more than one 
> server, we'll consider backing up server1 to the backup drives of 
> server2 and vice versa as added protection. In a pinch, server2 can 
> mount those drives for the end users to access almost immediately 
> should server1 go up in smoke, for example.
>
> If you want disaster recovery backup on top of this, then you need to 
> be able to take something off site. Realistically, thats a stack of 
> drives for a raid array, or a USB drive. That client I mentioned 
> previously with the 2TB data area takes 6 400Gig drives in a RAID 5 
> out of their backplane chassis and replaces them with a new set of 
> drives to start the snapshot process all over again. They keep one set 
> of drives off site. They swap the drives on an as needed basis, using 
> a 400Gig USB drive to backup the backup and take that off site nightly.
>
> The added benefit of this is that they can ship these drives to their 
> sister locations in a true disaster situation, or just to move a huge 
> amount of data between offices (Civil Engineers with tons of CAD 
> drawings). The other benefit is that the data is immediately usable. 
> No waiting for eons as a tape tries to find the file needed. Instant 
> access.
>
> So, when you say you want backup, think thru what you're trying to 
> protect against, and then get that set up.
>
Having considered your mindset, and knowing my client, I can 
confidentetly say that although they would like to SAY that they want a 
backup for a true dissaster, if I provide them with a quote for that 
service they will quickly change their mind. Your suggestion of in 
chasis drive backup, and not RAID seems very interesting, and I see your 
point where simple mirroring prooves useless for typical problems.

But I'd like to know what technologies (for lack of a better word) do 
you utilize to do the snapshoting? If you prefer, a few suggested google 
queries would  help.

On a side not, I find it amazing that computer can take that much a beating.