External SCSI Array

[feigned]

We're looking to move our mirrored arrays off of the database server into an external cd-tower.

Here's the one I'm considering:

http://servercase.com/miva/miva?/Me...uct_Code=CK7091&Category_Code=SCSI+Enclosures

It's a 9-bay, so getting our SCSI SCA drive planes (5 two-drive hardware mirrors) in there shouldn't pose any issue at all, but I'm more concerned about the external part of it. The irq's for the arrays that are in the server box now are fine, but if I use the external ports on the SCSI card in the box now, and route them to the external tower on seperate channels (like it is now), will things work out okay even though they would go through the 68-pin connectors on the back of that tower?

I know it shouldn't affect the mirrors (will backup beforehand), but I'm more worried about whether or not it would work at all if after the money would be spend on the case and two cables (roughly $250).

I'm actually not sure on upgrading the PSU. Could I just do the wire trick to use it without a motherboard, and have the on/off switch controlled by the switch on the PSU or the front, or what? Would 300w be enough for 10 drives to spin up on boot? nevermind that it's an unknown make and model PSU. I'm guesstimating a generous 30w for full-time operation of 10 drives, just need some other opinions.

Thoughts?

 

[86reddawg]

i have a 450 watt PS and it can handle 7 of the big scsi elites (7 lb full height drives) on bootup, but no more than that... try and find the power requirements on the scsi drive and do the calculations for 10 of them on bootup

 

[Neb]

Originally posted by feigned

It's a 9-bay, so getting our SCSI SCA drive planes (5 two-drive hardware mirrors) in there shouldn't pose any issue at all, but I'm more concerned about the external part of it. The irq's for the arrays that are in the server box now are fine, but if I use the external ports on the SCSI card in the box now, and route them to the external tower on seperate channels (like it is now), will things work out okay even though they would go through the 68-pin connectors on the back of that tower?

Look into your card's documentation, and make sure which external port is equal to which channel, then plug in the drives and you're set. The beauty of scsi is that it doesn't care at all if your drives happen to be inside or outside the case; as long as the drives have the same scsi ID and are properly terminated, your setup will work exactly the same.

I'm actually not sure on upgrading the PSU. Could I just do the wire trick to use it without a motherboard, and have the on/off switch controlled by the switch on the PSU or the front, or what? Would 300w be enough for 10 drives to spin up on boot? nevermind that it's an unknown make and model PSU. I'm guesstimating a generous 30w for full-time operation of 10 drives, just need some other opinions.

Considering it is an external enclosure, it's likely that the power supply is directly wired to the switch, so no need to mod anything. As for the power supply itself, I suggest looking up delayed spinup in your scsi card's bios options. Scsi drives tend to spin up more gently than their ide counterparts since they're generally designed for server use, and as such they don't need the quick spinup times of desktop drives so the spinup is much slower, resulting in a smaller power draw on start up. That, in combination of delayed spinup (which spins up your drives one by one based on scsi id, IIRC) allows you to use even the most weakest of power supplies to power scsi arrays

 

[Ice Czar]

and synch the PSUs, (if there isnt natively a provision for that?)
I corrupted the holy hell out of my IDE RAID when I first got it by not doing that
(was running 9 x HDDs of a seperate PSU, 6 off the RAID & 3 off a Trios)

restarts where the issue

a few links

Relay probably how youll need to do it

how I did it but thats when they are in the same box

Good Luck

Originally posted by Neb
Considering it is an external enclosure, it's likely that the power supply is directly wired to the switch, so no need to mod anything. As for the power supply itself, I suggest looking up delayed spinup in your scsi card's bios options. Scsi drives tend to spin up more gently than their ide counterparts since they're generally designed for server use, and as such they don't need the quick spinup times of desktop drives so the spinup is much slower, resulting in a smaller power draw on start up. That, in combination of delayed spinup (which spins up your drives one by one based on scsi id, IIRC) allows you to use even the most weakest of power supplies to power scsi arrays

that makes more sense

ignore me

 

[feigned]

Originally posted by Neb
Look into your card's documentation, and make sure which external port is equal to which channel, then plug in the drives and you're set. The beauty of scsi is that it doesn't care at all if your drives happen to be inside or outside the case; as long as the drives have the same scsi ID and are properly terminated, your setup will work exactly the same.

That's what I wasn't 100% sure on. I know the 3210S is only a 2-channel card and shouldn't have any problems going from internal to external, even though they're in the same SCA racks, but I wanted some second opinions.

Here's a question...if I used the external ports to go to the array tower, would I be able to use the internal ports at all? Say if I put a RAID 5 array on Interal #1, but with different IRQ's?

Considering it is an external enclosure, it's likely that the power supply is directly wired to the switch, so no need to mod anything. As for the power supply itself, I suggest looking up delayed spinup in your scsi card's bios options. Scsi drives tend to spin up more gently than their ide counterparts since they're generally designed for server use, and as such they don't need the quick spinup times of desktop drives so the spinup is much slower, resulting in a smaller power draw on start up. That, in combination of delayed spinup (which spins up your drives one by one based on scsi id, IIRC) allows you to use even the most weakest of power supplies to power scsi arrays

I remember reading about the sequential spin-up many months ago, but since I don't work with SCSI every day.... I'll have to dredge myself through that I2O BIOS to see if it's capable, but I'm placing my money on yes.

And Ice, I won't be doing any trickery with dual PSU's. I'm not that comfortable doing such a thing that involves $40 million worth of raw company data.

 

[Retro Rex]

If the Data is worth 40 million, why don't you buy something premade from IBM or something so it isn't your ass if the thing crashes?

 

[Neb]

Originally posted by feigned
That's what I wasn't 100% sure on. I know the 3210S is only a 2-channel card and shouldn't have any problems going from internal to external, even though they're in the same SCA racks, but I wanted some second opinions.

Here's a question...if I used the external ports to go to the array tower, would I be able to use the internal ports at all? Say if I put a RAID 5 array on Interal #1, but with different IRQ's?

I'm guessing by IRQ's, you mean scsi IDs because the only thing using an irq is the host adapter? Then yes, as long as you terminate it correctly. If you use both the internal and external ports, then your host controller is in the middle of the chain, so you'll need to turn off termination in the host adapter. Also remember to terminate the chain at both ends, and you'll be fine.

I remember reading about the sequential spin-up many months ago, but since I don't work with SCSI every day.... I'll have to dredge myself through that I2O BIOS to see if it's capable, but I'm placing my money on yes.

And Ice, I won't be doing any trickery with dual PSU's. I'm not that comfortable doing such a thing that involves $40 million worth of raw company data.

I also curious about this as with Retro Rex, why did you chose to make it yourself instead of offloading it to a premade solution? 40mil is a lot of responsibility to bear

 

[feigned]

Originally posted by Neb
I'm guessing by IRQ's, you mean scsi IDs because the only thing using an irq is the host adapter? Then yes, as long as you terminate it correctly. If you use both the internal and external ports, then your host controller is in the middle of the chain, so you'll need to turn off termination in the host adapter. Also remember to terminate the chain at both ends, and you'll be fine.

That's what I meant. Sorry. Termination is key there. Gotcha.

I also curious about this as with Retro Rex, why did you chose to make it yourself instead of offloading it to a premade solution? 40mil is a lot of responsibility to bear

Haven't ordered anything yet. An external array like this would cost several grand from big iron I'm sure. Two words: Japanese President. He's worried about the pennies when he should be concerned with the dollars.

More than anything I'm entertaining this idea. It may or may not happen. Also, going with a pre-made solution like that doesn't offload the liability of data loss to IBM.

 

[Neb]

Originally posted by feigned

Haven't ordered anything yet. An external array like this would cost several grand from big iron I'm sure. Two words: Japanese President. He's worried about the pennies when he should be concerned with the dollars.

I see, thats what I thought, but as long as you do your research, a home made solution can be as good as anything from the big corps

 

[feigned]

Originally posted by Neb
I see, thats what I thought, but as long as you do your research, a home made solution can be as good as anything from the big corps

Well, all of our servers are "built" by us so it's not like we're questioning our ability, just that there are some things not all of us know.

Thanks for the info.

 

[Neb]

oh yes, forgot about this:

PICS PLS!

[/mandatory request for pictures of final product]