[wellylug] Tape Backup Units

Wood Brent pcreso at pcreso.com
Mon Feb 16 20:43:15 NZDT 2004


--- Ewen McNeill <wellylug at ewen.mcneill.gen.nz> wrote:
> In message <40303278.2000808 at orcon.net.nz>, Jamie Dobbs writes:
> >recommend any? I feel that having the drives directly on the IDE bus 
> >would be a hell of a lot quicker than USB/Firewire, although I guess if 
> >I just start it backing up and go to bed then what does it matter.

30Gb in about 20 mins on an ext USB2 drive. about 6 hrs on the same unit on a
USB1 controller :-) A tyical SCSI DAT is quite a bit slower, but typically you
don't wait while a backup is running, so 1 hr or 3 hrs is not generally
critical. When a terabyte takes a week or so to backup you can start
considering performance issues (& yes, I've been there...)

I agree with Ewen's comment on Firewire performance, & have found USB2 to be
pretty similar, but more varied, depending more on chipset & driver issues.
There have been a few reviews of these, with some variations in throughput, but
I don't believe the difference between Firewire & USB2 is significant in this
context.


> Hotplugging IDE is generally not recommended.  There are a few devices
> which sort of try to provide that support, but the OS is still likely to
> get fairly upset if you don't tell it that the drive is going away.

That is one of the advantages of Linux, sync, mount & umount, etc fit nicely
into a backup script to flush any pending/buffered writes & unmount prior to
removing. It is not an elegant solution, as the IDE bus does not have
hotplugging built in, but it does seem to work pretty well. 

Note that a 5 1/4" ext USB/firewire box can have a removeable HD bay fitted.
That way you can disconnect via a genuinely hot-plugable bus, swap cold drives
via the IDE removeable carrier, & plug the USB/firewire back in. Gives you
hardware bus level removeability with dual (or more) swappable drives. 

Such boxes are readily available for ext CD/DVD drives, add a couple of HDD
removable bays/carriers & the 2 HD's & you have a pretty effective low cost,
high capacity, high performance backup.

Which drives to purchase is pretty much a matter of opinion, but I favour
Maxtor & IBM (Hitachi) at present. Seagate IDE drives I have found less
reliable, WD better, but still more failures than Maxtor & IBM. Maxtor are
generally more available & cheaper than IBM, making it an easy choice. See the
user relibility poll on www.storagereview.com before choosing, as some models
may be particulary good or bad, irrespective of the manufacturer. Samsung are
also getting up there now. They all have basic 1 yr warranty models & three yr
warranty models (except Samsung, which are all 3 yr). Silicon switched (partly
on my recommendation) from Seahgate to Maxtor a few years ago, & seem to be
quite happy with Maxtors, although they have also used WD when Maxtors were
unavailable. DON'T confuse this comment with server SCSI drives, Seagate seem
to have got that sector pretty right :-)

Re a later comment on this thread suggesting one large drive- if data security
is a goal, then two drives used alternately for total backups is much more
secure than two copies on a single larger capacity drive, esp as they can be
stored in separate locations, so floods & fires, etc might wipe out your
system, & even one backup drive kept in the same room, but a second drive can
ALWAYS be kept offsite.

Summat to note via my suggestion of Arkeia for LAN backups, it works well, but
if you want to backup a SCSI RAID array to a fast SCST DLT or LTO tape drive, I
have used separate SCSI buses for the tape & array, & a Gb LAN to keep the tape
streaming. Now that Gb LAN is so cheap, it is a pretty reasonable option
allowing multiple boxes on a LAN to share a backup device. 100Mbit isn't really
viable.


It boils down to how valuable is your data & how much can you afford to ensure
it can't be lost. 

Enough on the list from me about this, email privately if you have specific
questions (pcreso at pcreso.com). 


Cheers,
 
  Brent Wood




More information about the wellylug mailing list