[Sunhelp] How many tape drives?

Thu Aug 26 16:20:36 CDT 1999

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I'm working on putting together some Sun boxes that are going to act as
backup servers for our server farms. I've got my tape and slot capacity
numbers together, and now I'm looking at the type of box I'm going to need
to drive the tapes. 

We're currently deciding between using DLT7000 drives and the Storagetek
9840 drives, so I have sizing for both configurations. 

In the DLT7000 option, the specs call for 13 drives on a single backup
server. 

In the STK 9840 option, the specs call 10 drives on a single backup server.

Here's where I need some input from the list:

I understand that the rule of thumb is no more than 2 DLT7000 or 9840 drives
per SCSI channel, so I would need 7 SCSI channels for the DLT7000 option,
and 5 channels for the STK 9840 option. Does that sound about right?

Where I'm really stuck is sizing the number and speed of the CPU's in the
backup server. I've been told by our backup software vendor (Veritas) that
we should plan on 2 drives per CPU. However, I have been told by STK that we
can get away with driving 10 9840 drives with 4 400mhz processors. 

That's quite a wide range of server chassis we can look at. If we follow the
Veritas suggestions, we'd be looking at a 5 - 7 processor E4500. On the
other hand if we follow the STK suggestions, conceivably we could put the
backup server on a 4 processor E450. There's quite a wide price range
between the two. 

On one hand, I'd hate to go with an E4500 when its not nessisary, but I need
to be careful to avoid starting out with a box that is underpowered and has
to be flat out replaced. 

What has been everyone else's experience in terms of the number of drives
per CPU?

Thanks!

-- Nick Steel
Infrastructure Technologist
Distributed Server Infrastructure
Sempra Energy
V. 323-780-5042
E. nsteel at sempra.com

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<TITLE>How many tape drives?</TITLE>
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I'm working on putting together some Sun boxes that =
are going to act as backup servers for our server farms. I've got my =
tape and slot capacity numbers together, and now I'm looking at the =
type of box I'm going to need to drive the tapes.

We're currently deciding between using DLT7000 drives =
and the Storagetek 9840 drives, so I have sizing for both =
configurations.

In the DLT7000 option, the specs call for 13 drives =
on a single backup server.

<P><FONT SIZE=3D2>In the STK 9840 option, the specs call 10 drives on a =
single backup server.</FONT>
</P>

<P><FONT SIZE=3D2>Here's where I need some input from the list:</FONT>
</P>

I understand that the rule of thumb is no more than 2 =
DLT7000 or 9840 drives per SCSI channel, so I would need 7 SCSI =
channels for the DLT7000 option, and 5 channels for the STK 9840 =
option. Does that sound about right?

Where I'm really stuck is sizing the number and speed =
of the CPU's in the backup server. I've been told by our backup =
software vendor (Veritas) that we should plan on 2 drives per CPU. =
However, I have been told by STK that we can get away with driving 10 =
9840 drives with 4 400mhz processors.

That's quite a wide range of server chassis we can =
look at. If we follow the Veritas suggestions, we'd be looking at a 5 - =
7 processor E4500. On the other hand if we follow the STK suggestions, =
conceivably we could put the backup server on a 4 processor E450. =
There's quite a wide price range between the two.

On one hand, I'd hate to go with an E4500 when its =
not nessisary, but I need to be careful to avoid starting out with a =
box that is underpowered and has to be flat out replaced.

<P><FONT SIZE=3D2>What has been everyone else's experience in terms of =
the number of drives per CPU?</FONT>
</P>

<P><FONT SIZE=3D2>Thanks!</FONT>
</P>

-- Nick Steel
 Infrastructure Technologist
 Distributed Server Infrastructure
 Sempra Energy
 V. 323-780-5042
 E. nsteel at sempra.com

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