[CentOS] slow usb hard disk performance.

Bryan J. Smith thebs413 at earthlink.net
Mon Dec 5 21:07:19 UTC 2005


"William A. Mahaffey III" <wam at HiWAAY.net> wrote:
> 19 GiB in 36 minutes, I wouldn't be complaining either :-).

It's not bad at all.

> I'm using DDS-2 & 3, & they are MUCHO slower ....

As I mentioned, DDS-2 is 15 years old and a measly 0.8MBps
native.  DDS-3 is about 10 years old and about 1.6MBps.

Tape is one of those commodities that really require a
minimum of a $1K investment with something like VXA.  And if
you really can, it's best to spend $3-4K and go for the gold
in something like LTO-3 with its 400GB native capacity and
80MBps transfer rate (double each with hardware compression).

Anything less really isn't worth it.  Especially not at the
cost of backup cartridges.

> I do also backup across my network to a sorta-spare HDD on
> another box,  but use the DAT tapes for remote storage. 

Which is what many organization should do.  They should
guarantee they get some sort of daily backup, which is
easiest to do with disk.  Especailly when just doing
sychronization of diffs, which drastically cuts down on
network usage -- especially during the all important "backup
window."

It's also easier to restore, easier to do just about
everything when you have a full copy on random access disk. 
It is also easier to backup tape, directly, locally and 24x7
-- no more backup window constraints -- from that server. 
It's also easier to verify backups against original, when the
backup server has a local copy -- again, at any time, 24x7,
not bothering the network.

When I integrated any solution, I always told the client to
put in 4x the disk they needed, then another 2.5x that size
(for a total of 14x) for snapshots, disk backup, etc... 
Ideally this is a separate system, but in the worst case, it
was just a separate array.  If you're spending $4K on a
server with such storage, then another $1K on basic tape
backup is well worth it.

> I might need to look into a firewire/USB disk for that 
> at those speeds :-).

FireWire is pretty commodity these days on at least AMD
platforms.  I've had far less headaches with it, as long as
I'm not running "on-line" data with it.  I never do it with
FireWire _or_ USB for that matter.

If I need something "on-line," I still use external SCSI LVD.
 SAS will become my preferred favorite soon enough.
 


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Bryan J. Smith                | Sent from Yahoo Mail
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