hi guys,

just need a little help with some maths here;

i have 10 x tape drives that can do 50MB/sec each

i have a server that has 42GB of data to be backed up over a
100Mbit/sec LAN to these tape drives

assuming no compression on the drives and that the LAN link is not
shared (no other data over it) etc, can someone confirm that the
following is the way to work out how quickly i can back this up?

42*1024*1024 (to get MB)
44040192/500 (devide 42MB by 500MB/sec)

/100 (devide by 100mbit link)

/60 (device to mins)

so, 42Gig over 100Mbit line using 10tape drives, each doing 50MB/sec =
14.68minutes

is this the correct way to work this out?

cheers

[ Post a follow-up to this message ]

> i have 10 x tape drives that can do 50MB/sec each
>
> i have a server that has 42GB of data to be backed up over a
> 100Mbit/sec LAN to these tape drives

I would upgrade to 1GBps LAN. Not so expensive usually.

> so, 42Gig over 100Mbit line using 10tape drives, each doing 50MB/sec =
> 14.68minutes

The link is the slowest place. So, 42GB / 100Mbps = 3440.64s = ~57min, with 
the
tapes actively shoe-shining (restarting streaming).

--
Maxim Shatskih, Windows DDK MVP
StorageCraft Corporation
maxim@storagecraft.com
http://www.storagecraft.com

[ Post a follow-up to this message ]

thanks maxim,

ok, assume i've upgraded to 1Gbps LAN, so how do i do the math now?


Maxim S. Shatskih wrote:
 
>
> I would upgrade to 1GBps LAN. Not so expensive usually.
> 
>
> The link is the slowest place. So, 42GB / 100Mbps = 3440.64s = ~57min, wit
h the
> tapes actively shoe-shining (restarting streaming).
>
> --
> Maxim Shatskih, Windows DDK MVP
> StorageCraft Corporation
> maxim@storagecraft.com
> http://www.storagecraft.com

[ Post a follow-up to this message ]

deggs wrote:
> thanks maxim,
>
> ok, assume i've upgraded to 1Gbps LAN, so how do i do the math now?

Maxim's maths still applied. The 1Gbps LAN link can deliver 100MBps so
that's the fastest speed at which you can pull data off the server.

While the 10 tapes drives have a total, theoretical throughput of
500MBps the network won't go that fast. Plus, as Maxim says, you'll
probably end up with shoe-shining.

You might be better off with a tape library with a couple of drives.


> Maxim S. Shatskih wrote:
> 
>

[ Post a follow-up to this message ]

thanks

i guess im after some help with the basics...how do i get form mbytes
to mbits and the other way round? also, could you go through the
indevedual steps to calculate the numbers you have come out with? i.e.
how did you get 3440.64secons? etc.

thanks again - i'm very new to this (as you may tell already) :-o

On Jan 17, 10:00 pm, Guy Dawson <g...@cuillin.org.uk> wrote:[vbcol=seagreen]
> deggs wrote: 
> 
> that's the fastest speed at which you can pull data off the server.
>
> While the 10 tapes drives have a total, theoretical throughput of
> 500MBps the network won't go that fast. Plus, as Maxim says, you'll
> probably end up with shoe-shining.
>
> You might be better off with a tape library with a couple of drives.
> 
> 
> 
> 
> 

[ Post a follow-up to this message ]