[Gllug] Unattended backup solution

[Russell Howe]

On Sun, Aug 14, 2005 at 09:07:11AM +0100, Chris Bell wrote:
>    I am very dubious about plug-in drive caddies, the ones I have seen were
> not good quality and appeared to inhibit drive cooling.

The plastic ones tend to be pretty poor in this regard, even when they
incorporate fans (which tend to be tiny and unreliable anyway).

I have some Lian-Li aluminium pullout bays, which were about 35 quid
each IIRC. My drives ran cooler when installed in these than they did
beforehand (45 degrees C to 33):

$ hddtemp /dev/hdc
/dev/hdc: ST3160023A: 33°C

> I am also very
> dubious about repeated drive swapping because of the connector quality,

The IDE ones tend to have an internal connector which plugs into the
drive, and then they have their own interface between drive tray and
chassis (the Lian-Li ones use a large Centronics-style connector, which
carries data and power). Wear and tear is thus on the drive bay and
tray, not the drive's contacts.

Still, these are not hotswap bays. They are just removable drive trays.

I also have some SCA SCSI hotswap drive trays (pcicase SNT-131C). The
chassis side of these has connectors for 68pin SCSI and molex power
cable, and has an 80pin SCA socket on the inside.

The drive tray just holds the drive in the right place so that when
inserted, the drive's SCA connector mates with the drive bay's. Thus the
wear and tear is between the chassis mount and the drive connector. This
may be a concern to you, but since most of the hotswap SCSI drives in
use today seem to be SCA drives, if it was a problem then you'd
probably hear more about it.

Still, these tend to be hotswap in order that they can be replaced upon
failure without shutting the system down, rather than for frequent
removal and reinsertion as you would do for a backup system. For that,
I'd use USB or Firewire - the connectors are designed for repeated
connection and disconnection and should they wear out, replacements are
dirt cheap.

I'd still back up to tape at least once a week though. I'm thinking
about doing a backup to disk as well as tape, so that restoration of
accidentally deleted files doesn't require tapes and will be faster.
This way the tapes are purely for disaster recovery (but still need
periodic testing!!)

> especially with the standard power lead giving variable volts loss.

What do you mean? How do the electrical characteristics of the power
supply affect hotpluggability?

-- 
Russell Howe       | Why be just another cog in the machine,
rhowe at siksai.co.uk | when you can be the spanner in the works?
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