qla2xxx behavior with changing volumes

qla2xxx behavior with changing volumes

[Sean Bruno]

What is the expected behavior when volumes on a SAN change size and LUN
ID order?

I've noticed that if a volume changes size, leaves the SAN or changes
target ID it isn't auto-magically picked up by a 2.6.18 based
system(running CentOS 5).

If a new target appears on the SAN however, it is noticed and assigned a
new drive letter.

Sean

Re: qla2xxx behavior with changing volumes

[Vladislav Bolkhovitin]

Sean Bruno wrote:
> What is the expected behavior when volumes on a SAN change size and LUN
> ID order?
> 
> I've noticed that if a volume changes size, leaves the SAN or changes
> target ID it isn't auto-magically picked up by a 2.6.18 based
> system(running CentOS 5).
> 
> If a new target appears on the SAN however, it is noticed and assigned a
> new drive letter.

For changes in the volume size the target (SAN) should generate 
"CAPACITY DATA HAS CHANGED" Unit Attention.

For changes in the LUN ID order the target should generate "REPORTED 
LUNS DATA HAS CHANGED" Unit Attention.

On these notifications initiator is supposed to make the appropriate 
actions, like rescan the SAN in case of "REPORTED LUNS DATA HAS 
CHANGED". Unfortunately, Linux just ignores them as well as the majority 
of other Unit Attentions, hence you have to restart the system or, at 
least, the corresponding driver to see the changes.

Vlad

Re: qla2xxx behavior with changing volumes

[Vladislav Bolkhovitin]

Vladislav Bolkhovitin wrote:
> Sean Bruno wrote:
> 
>> What is the expected behavior when volumes on a SAN change size and LUN
>> ID order?
>>
>> I've noticed that if a volume changes size, leaves the SAN or changes
>> target ID it isn't auto-magically picked up by a 2.6.18 based
>> system(running CentOS 5).
>>
>> If a new target appears on the SAN however, it is noticed and assigned a
>> new drive letter.
> 
> 
> For changes in the volume size the target (SAN) should generate 
> "CAPACITY DATA HAS CHANGED" Unit Attention.
> 
> For changes in the LUN ID order the target should generate "REPORTED 
> LUNS DATA HAS CHANGED" Unit Attention.
> 
> On these notifications initiator is supposed to make the appropriate 
> actions, like rescan the SAN in case of "REPORTED LUNS DATA HAS 
> CHANGED". Unfortunately, Linux just ignores them as well as the majority 
> of other Unit Attentions, hence you have to restart the system or, at 
> least, the corresponding driver to see the changes.

Or, I forgot, do the manual rescan via sysfs "rescan". Sometimes it 
helps too.

> Vlad
>