[nylug-talk] Recommendations for encrypted tape drive(s)?

[Peter C. Norton]

On Tue, Mar 04, 2008 at 07:25:14PM -0500, Chris Knadle wrote:
> On Tuesday 04 March 2008, Luis Murillo wrote:
> > Ok, I agree some of the data you provide is not something I can go up
> > against at...but one thing I can say that you missed is the LTO4
> > speed...the LTO4 can reach speeds of up to 240MBps on an ideal system
> > but since that's not always correct, I've seen the drives work around
> > 160MBps and would consider a drive that is doing less that 150MBps to
> > be having performance issues...at least on SCSI :)
> 
>    Just out of curiosity I wanted to know how long it would take to back up 
> the 30 TB number that Peter mentioned (with a single device):
> 
>     Rate        Time
> ---------------------------
>    240 MB/s   36.4 hours
>    160 MB/s   54.6 hours
>    120 MB/s   72.8 hours

Yeah, so 240, or 160 is the "tolerable" timeframe for weekend fully
backups, or montly weekend full backups, with incrimentals taken
periodically. Considering the sun thumper (aka x4500
http://www.sun.com/servers/x64/x4500/) can hold 46 ide data disks once
you've mirrored the root disks, the 30TB  starting point is only about
70% of the capacity of a single system in a rack at an "affordable"
price (that is, a fair fraction of most other solutions that put this
much storage into a single enclosed device).
 
> 
>    So if an LTO4 is the fastest drive available and a company wants to do a 
> full backup every 24 hours (most probably don't but some do), then it seems 
> like a lot more than a single tape device is required.

Does anyone do full backups on "large" systems daily to tape? I've
never seen it managed any other way except perhaps a copy to
annother disk system (eg. databases dumps to disk) followed by full
dumps and incrimentals afterwards).
 
> > The scenario I wrote about it's completely true...I've seen it happen
> > on the drives that I support.
> 
>    Yeah, at those kinds of data rates I'd believe that.  That's probably an 
> interesting profile to consider concerning kernel scheduling.

Yep. All of it is super cool now.

-Peter

-- 
The 5 year plan:
In five years we'll make up another plan.
Or just re-use this one.