As Gustin said, with a bit more info:
We implemented the NAS when a standard server computer with a RAID
controller started to fail. Luckily we were able to at least get one
pass of RSYNC done before the controller died outright. So while we
already had a RAID 5 solution, the failure of the hardware made that
useless. (The RAID controller was no longer available...)
So we were hit by the same scenario Gustin mentioned. We had redundancy
in our drives but not a backup. Loosing the controller, or if someone
deleted the wrong file would result in that data being irretrievable.
So the immediate concern was restoring normal operations by providing
access to the data. We of course wanted to protect against drive
failure, so opted for disk mirroring (RAID 10 actually, with 4 drives)
THEN we took a serious look at our backup system. It didn't exist (I
just love inheriting other people's work!). So we implemented a second
NAS for this purpose. We had a LARGE quantity of data to move around
(TBs), so we considered and discarded online backup solutions as the
data bandwidth would cost too much in terms of time. By implementing
the second NAS locally, we could utilize local network bandwidth at no
additional costs, and opened the option of moving the second NAS server
off-site after the initial SYNC was completed.
Now, we have protection against the NAS components failing AND against a
drive failure. That is sufficient backup in our case.
Hope that helps clarify things Joe. :)
Shawn
On 14-06-02 12:08 AM, Joe S wrote:
Does not RAID with more than 1 drive give a backup? Why do I
need an additional hard drive to back up to?
On Sun, 01 Jun 2014 22:16:06 -0600
Shawn Grover <sgro...@open2space.com> wrote:
I bow to the other info presented in this thread. But I can
comment a little on the hardware.
We picked up both a 2 bay and 4 bay QNAP box at work. Both
have been running very reliably and are surprisingly quite.
Both are loaded up with 4TB drives. The 2 bay unit is
configured in Raid1, so it has a total of 4TB capacity (well,
slightly less...). The 4 bay unit is configured with Raid10,
giving us 8TB storage, with another 8TB of hot fail. The 2
unit device serves as an RSYNC target for the 4 unit device
- purely a back up system. ( later picked up a cheaper more
consumer brand 2 bay QNAP for home use and have enjoyed good
success with it as well.)
With this configuration we are reasonably sure we can recover
data quickly should we ever loose a drive. This was NOT the
case when the hardware RAID 5 controller on the storage server
that pre-dated these boxes decided to crap out. Luckily I was
able to get most of our data from the RAID 5 array before it
went for good.
The one thing I would do different with the current
arrangement is to move the 2 unit backup NAS offsite. Now
that it has been sync'd locally, doing RSYNCs over the
Interwebs would be a minor inconvenience. We did some quick
math about doing a remote backup of everything from scratch
and arrived at somewhere between 2 to 4 weeks of solid data
transfer, utilizing the available bandwidth we typically see.
So I'd recommend a local RSYNC if possible, then move the
backup device and then set up remote backups to minimize the
data transfer hits for that initial backup.
My thoughts.
Shawn
On 14-05-30 10:20 AM, Bogi wrote:
Hi Joe,
Having a single drive external, while better than nothing is
way not as good as having a 2 bay / drive raid 1 enclosure.
in terms of safety i am talking. A step up in terms of
safety would be a 4 drive raid 1 or 5 enclosure. A step up
in all these cases, is having the drives/enclosures as a NAS
device sitting in a different place (safer?) than the backed
up computers are, and connected with the network to them.
Most 2-4 drive enclosures (that come with drives) state the
capacity as a raid 0, which can be tricky for the
uninitialized. A raid0 configuration will not increase
safety, in fact it will reduce it drastically, so when
looking at populated 2 - 4 drive units, as a rule of thumb,
half the capacity for 2 disk units (to get the capacity in
raid 1 terms). the 4 disk raids a bit more complicated. you
can treat them as 2 pairs, this halving the capacity, or as
a 4 disk raid 5, in which case you get 75% of the total disk
capacities.
For direct connect enclosures, look for e-sata capability,
look for usb3 , specially if your backed up computer has
these ports, you can not go wrong with these features.
For NAS devices, look for the once that have dual gigabit
Ethernet connectors, they usually perform better speed wise.
If you are going to invest on a 2-4 or more drive external
nas unit, think about augmenting it with UPS (uninterrupted
power supply), for capacity, add up the power rating on the
NAS unit. If you want to skimp out on the UPS, just get a
surge protector, it's your data after all.
Here are some pointers:
Single drive, direct connection:
http://www.memoryexpress.com/Products/MX45802
http://www.memoryexpress.com/Products/MX22324
Dual drive, direct connection:
http://www.memoryexpress.com/Products/MX40154
http://www.memoryexpress.com/Products/MX43461
4 drive, direct connection:
(do consider the noise of 4 drives spinning near your
desktop)
http://www.memoryexpress.com/Products/MX30898/Reviews and of
course the drobo:
http://www.memoryexpress.com/Products/MX42950
Single drive, NAS:
http://www.memoryexpress.com/Products/MX32282
http://www.memoryexpress.com/Products/MX33812
Dual drive, NAS:
http://www.memoryexpress.com/Products/MX47066
http://www.memoryexpress.com/Products/MX49052
4 drive , NAS:
http://www.memoryexpress.com/Products/MX39139
http://www.memoryexpress.com/Products/MX49654
And you still need to get your drives.
Generally look for NAS / Storage rated drives, Green rated
drives tend to perform poorly in raid environments.
Desktop / workstation rated drives will do fine, specially
under low/medium stress situations.
On May 29, 2014 Thursday 14:22:21 Joe S wrote:
I was reading the reviews of external hard drives. I found a
number had problems with reliability. I don't have
experience with these, but need something for backing up my
home computer. Are there any that can be recommended? I
also thought of getting an enclosure and a regular drive in
case I have to replace it in the future. Probably 1 TB or
so.
Thanks for suggestions
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