Dick Sidbury <DrJamesSidb
...@hotmail.com> wrote:
> I just ordered a Drobo (4 bays, usb+FW800) and will need to get some
> disk drives for them. I would like to poll the readers of this group to
> see whether you're using "green" drives or "performance" drives in your
> Drobo and if you've tried both, which you would recommend.
I got my Drobo (same model) about two months ago, and so far I have a
couple of WD enterpise class "green" drives in it. My main reason for
having the Drobo is expandable storage capacity, not speed, so I don't
care if the drives are a little slower. Lower power consumption will
also help as I'm running the Drobo and Mac Mini Server via a UPS, to
allow orderly shutdown in a power outage (and avoiding shutdown in short
outages).
Enterprise drives rather than mainstream ones are theoretically a better
choice in a RAID as they don't try as hard to recover from errors, thus
allowing the RAID controller to discover the error before getting a
timeout, and deal with it by recovering the data from another drive (and
then testing and/or eliminating a bad sector).
> Right now I'm using some old 500gb non-green drives to try to see how the
> system performs. So far it looks like it will take Time Machine about 25
> or thirty hours to back up my mac pro (about 1.7tb of stuff all of which
> is on performance drives except for the SSD boot drive which has 80gb of
> stuff).
Are you intending to store anything other than TM backups on the Drobo?
If so, how have you structured the TM backup? A standard local TM backup
on a non-partitioned drive will eventually expand to fill the entire
drive, and that will be problematic for a Drobo as its nominal capacity
is usually larger than its actual capacity.
The capacity used by a TM backup can be limited by partitioning the
Drobo (which has to wipe the Drobo, so should be done first), or by
arranging the computer to do a TM backup into a disk image (as it
normally does for networked backups), and then set the maximum size of
the disk image.
One point I've deduced with the Drobo is that you should avoid having
all four drives the same capacity, because it means you have to replace
two drives before you can increase the capacity, and you have to wait
for the first one to copy before the next one can be added.
I've started with two 2 TB drives. If I need more capacity I'll add some
smaller ones temporarily (I have 1.5 TB and 500 GB drives I could
reuse). Once I have four drives in the Drobo, I'll keep replacing the
smallest drive with something bigger than 2 TB, avoiding the "all the
same size" situation.
Optimal use of the hard drives occurs if the two largest capacity drives
are the same capacity.
With the current Thailand situation, I don't expect to be able to get
affordable 2.5+ TB drives for at least a year, but I should be able to
manage with smaller capacity drives in the meantime.
--
David Empson
demp...@actrix.gen.nz
