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Home > Archive > Data Storage > March 2006 > EMC SAN
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| Red Cross 2006-03-19, 11:47 am |
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I have an EMC san (clarrion) with a number of servers attached to it.
Its entirely supported by a third party company, though, the 'never
would happen' event has happened twice now. Which means natural
disaster and I have to go in and shutdown everything.
I shutdown all the servers, though I leave the SAN running on the UPS,
once the 16kva UPS runs dead, power just dies to the SAN.
Is this the correct way to do it? I read that shutting down the
servers, the EMC san then after detecting a power failure (ups going
dead) will destage any data in cache, write to the array and spin the
disks down.
Ive asked the third party company for the details though they just dont
want to answer the question and would prefer we paid them $1200 after
hours emergency call out fee to shut the system down.
any help is most appreciate.
Josh.
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| On 19 Mar 2006 01:05:35 -0800, "Red Cross" <redcross1@gmail.com>
wrote:
>I shutdown all the servers, though I leave the SAN running on the UPS,
>once the 16kva UPS runs dead, power just dies to the SAN.
>
>Is this the correct way to do it? I read that shutting down the
>servers, the EMC san then after detecting a power failure (ups going
>dead) will destage any data in cache, write to the array and spin the
>disks down.
Why would you do that? If you know that the power is going to fail,
it would be prudent to shut your SAN down also.
Yes, the Clariion will destage any data in cache out to disk and if
your servers are off, there won't be any write data there. You're
relying on the Clariion detecting the UPS status in order to shut
itself down cleanly. Much kinder to shut the Clariion down in the
proper manner.
HVB
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| Red Cross 2006-03-19, 11:47 am |
| That is why I was asking.. its not something I would do out of
preference.. but other people in other threads suggested this is
normal.
Care to share how you can shutdown the SAN?
I log into the web interface and I can see no where how to shut it
down.
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| On 19 Mar 2006 03:59:11 -0800, "Red Cross" <redcross1@gmail.com>
wrote:
>That is why I was asking.. its not something I would do out of
>preference.. but other people in other threads suggested this is
>normal.
It's normal for the Clariion to behave like that, if you have a power
failure. Not normal to just let it happen.
>Care to share how you can shutdown the SAN?
Sure...
>I log into the web interface and I can see no where how to shut it
>down.
You won't find any 'power down' feature in the software - quite
deliberately.
You didn't say which Clariion you have, but this applies to a CX500
(and most likely any other CX model).
1 - Stop all i/o to the array
2 - Turn off power to each SPS
3 - Turn off power to each DAE
Make sure you're not pulling the power for the SP itself in step 2. Be
ultra-certain it's the SPS, otherwise you risk losing data in cache.
The process is very similar to what would happen in a power out
situation, but at least you're in control.
HVB
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| Red Cross 2006-03-21, 2:55 am |
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HVB wrote:
> On 19 Mar 2006 03:59:11 -0800, "Red Cross" <redcross1@gmail.com>
> wrote:
>
>
> It's normal for the Clariion to behave like that, if you have a power
> failure. Not normal to just let it happen.
>
>
> Sure...
>
>
> You won't find any 'power down' feature in the software - quite
> deliberately.
>
> You didn't say which Clariion you have, but this applies to a CX500
> (and most likely any other CX model).
>
> 1 - Stop all i/o to the array
> 2 - Turn off power to each SPS
> 3 - Turn off power to each DAE
>
> Make sure you're not pulling the power for the SP itself in step 2. Be
> ultra-certain it's the SPS, otherwise you risk losing data in cache.
>
> The process is very similar to what would happen in a power out
> situation, but at least you're in control.
>
> HVB
Right, so add in the simple step of stopping the I/O to the array and
manualy perform the steps it automatically does itself?
The way I see it, is stop the I/O to the array and letting it do its
thing by itself.. pulling power is simply doing whats happening, power
is dropping. Except by manually pulling you add in a step that can go
wrong, ie if you pull the power to the wrong part first.
Thanks for your help. ill test stopping the I/O and let the san smarts
be smart and power itself off.
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| On 20 Mar 2006 04:32:03 -0800, "Red Cross" <redcross1@gmail.com>
wrote:
<big snip>
>Right, so add in the simple step of stopping the I/O to the array and
>manualy perform the steps it automatically does itself?
Yep, that's it.
>The way I see it, is stop the I/O to the array and letting it do its
>thing by itself.. pulling power is simply doing whats happening, power
>is dropping. Except by manually pulling you add in a step that can go
>wrong, ie if you pull the power to the wrong part first.
You have control. You're not waiting on your UPS to die first.
>Thanks for your help. ill test stopping the I/O and let the san smarts
>be smart and power itself off.
Enjoy!
HVB
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| Globe Treader 2006-03-21, 2:55 am |
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>1 - Stop all i/o to the array
>2 - Turn off power to each SPS
>3 - Turn off power to each DAE
>Make sure you're not pulling the power for the SP itself in step 2. Be
>ultra-certain it's the SPS, otherwise you risk losing data in cache.
as noted by others, clariions do not provide software shutdown. you
need to turn off power to the standby power supplies.
how to locate sps -> the sps have a black rocker switch on them. power
cable from rack goes in the sps and one power cable from sps goes to
the storage processors. on higher models (600/700) second power cable
goes to first drive enclosure. in prev models its unused.
to make sure all the io has stopped, its advisable to shut down all the
connected hosts..after that turn off both sps by moving the rocker
switches. this will start the array to flush the cache data and then
shutdown automatically.
once the lights on sps go off, its safe to turn off power to drive
enclosures too.
>Yes, the Clariion will destage any data in cache out to disk and if
>your servers are off, there won't be any write data there. You're
>relying on the Clariion detecting the UPS status in order to shut
>itself down cleanly.
this is *ideal* assumption...i have seen unhappy customers after power
outage. its better to shut down the array than leave it as it is...if
you cant do it (if you are managing array remotely) atleast disable the
write/cache on array and remember to turn it on once the power is back
to normal (which most forget and call in for performance slowdown).
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