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* [dm-devel] [PATCH] multipath-tools: update no_path_retry value for IBM/2145
@ 2021-08-25 22:24 Xose Vazquez Perez
  2021-08-26  6:47 ` Martin Wilck
  0 siblings, 1 reply; 3+ messages in thread
From: Xose Vazquez Perez @ 2021-08-25 22:24 UTC (permalink / raw)
  Cc: Xose Vazquez Perez, Martin Wilck, DM-DEVEL ML

Based on current configs: https://www.ibm.com/docs/en/flashsystem-9x00/8.4.x?topic=system-settings-linux-hosts

Cc: Martin Wilck <mwilck@suse.com>
Cc: Benjamin Marzinski <bmarzins@redhat.com>
Cc: Christophe Varoqui <christophe.varoqui@opensvc.com>
Cc: DM-DEVEL ML <dm-devel@redhat.com>
Signed-off-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
---
 libmultipath/hwtable.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/libmultipath/hwtable.c b/libmultipath/hwtable.c
index 2a896440..58554cbb 100644
--- a/libmultipath/hwtable.c
+++ b/libmultipath/hwtable.c
@@ -662,7 +662,7 @@ static struct hwentry default_hw[] = {
 		/* Storwize family / SAN Volume Controller / Flex System V7000 / FlashSystem V840/V9000/9100 */
 		.vendor        = "IBM",
 		.product       = "^2145",
-		.no_path_retry = NO_PATH_RETRY_QUEUE,
+		.no_path_retry = 5,
 		.pgpolicy      = GROUP_BY_PRIO,
 		.pgfailback    = -FAILBACK_IMMEDIATE,
 		.prio_name     = PRIO_ALUA,
-- 
2.32.0

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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [dm-devel] [PATCH] multipath-tools: update no_path_retry value for IBM/2145
  2021-08-25 22:24 [dm-devel] [PATCH] multipath-tools: update no_path_retry value for IBM/2145 Xose Vazquez Perez
@ 2021-08-26  6:47 ` Martin Wilck
  2021-08-30 16:57   ` Steffen Maier
  0 siblings, 1 reply; 3+ messages in thread
From: Martin Wilck @ 2021-08-26  6:47 UTC (permalink / raw)
  To: Xose Vazquez Perez; +Cc: DM-DEVEL ML

On Thu, 2021-08-26 at 00:24 +0200, Xose Vazquez Perez wrote:
> Based on current configs:
> https://www.ibm.com/docs/en/flashsystem-9x00/8.4.x?topic=system-settings-linux-hosts
> 
> Cc: Martin Wilck <mwilck@suse.com>
> Cc: Benjamin Marzinski <bmarzins@redhat.com>
> Cc: Christophe Varoqui <christophe.varoqui@opensvc.com>
> Cc: DM-DEVEL ML <dm-devel@redhat.com>
> Signed-off-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
> ---
>  libmultipath/hwtable.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/libmultipath/hwtable.c b/libmultipath/hwtable.c
> index 2a896440..58554cbb 100644
> --- a/libmultipath/hwtable.c
> +++ b/libmultipath/hwtable.c
> @@ -662,7 +662,7 @@ static struct hwentry default_hw[] = {
>                 /* Storwize family / SAN Volume Controller / Flex
> System V7000 / FlashSystem V840/V9000/9100 */
>                 .vendor        = "IBM",
>                 .product       = "^2145",
> -               .no_path_retry = NO_PATH_RETRY_QUEUE,
> +               .no_path_retry = 5,
>                 .pgpolicy      = GROUP_BY_PRIO,
>                 .pgfailback    = -FAILBACK_IMMEDIATE,
>                 .prio_name     = PRIO_ALUA,

Ref: https://github.com/opensvc/multipath-tools/issues/6

The question is on which basis IBM came up with this recommendation.
5 (aka 25s) is a rather low value. Some users may encounter unpleasant
surprises if we change the default this way, as it used to be infinite
before.

Using 5, the IBS 2145 would have the 2nd-lowest default in hwtable.c
after Dell PowerStore (3). Symmetrix has 6; all other arrays default to
10 or higher, many default to "queue".

Observing that the above is the documentation for the *Flashsystem*
9200,  I consider it likely that the value ".no_path_retry = 5" would
apply to flash-based IBM storage products, but not to the older
products such as the V7000, which unfortunately use the same device ID.

It'd be helpful if someone from IBM could jump in here...

Pondering the pros and cons, I vote for keeping the current defaults
for now.

Martin



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^ permalink raw reply	[flat|nested] 3+ messages in thread

* Re: [dm-devel] [PATCH] multipath-tools: update no_path_retry value for IBM/2145
  2021-08-26  6:47 ` Martin Wilck
@ 2021-08-30 16:57   ` Steffen Maier
  0 siblings, 0 replies; 3+ messages in thread
From: Steffen Maier @ 2021-08-30 16:57 UTC (permalink / raw)
  To: dm-devel; +Cc: Benjamin Block

On 8/26/21 8:47 AM, Martin Wilck wrote:
> On Thu, 2021-08-26 at 00:24 +0200, Xose Vazquez Perez wrote:
>> Based on current configs:
>> https://www.ibm.com/docs/en/flashsystem-9x00/8.4.x?topic=system-settings-linux-hosts
>>
>> Cc: Martin Wilck <mwilck@suse.com>
>> Cc: Benjamin Marzinski <bmarzins@redhat.com>
>> Cc: Christophe Varoqui <christophe.varoqui@opensvc.com>
>> Cc: DM-DEVEL ML <dm-devel@redhat.com>
>> Signed-off-by: Xose Vazquez Perez <xose.vazquez@gmail.com>
>> ---
>>   libmultipath/hwtable.c | 2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/libmultipath/hwtable.c b/libmultipath/hwtable.c
>> index 2a896440..58554cbb 100644
>> --- a/libmultipath/hwtable.c
>> +++ b/libmultipath/hwtable.c
>> @@ -662,7 +662,7 @@ static struct hwentry default_hw[] = {
>>                  /* Storwize family / SAN Volume Controller / Flex
>> System V7000 / FlashSystem V840/V9000/9100 */
>>                  .vendor        = "IBM",
>>                  .product       = "^2145",
>> -               .no_path_retry = NO_PATH_RETRY_QUEUE,
>> +               .no_path_retry = 5,
>>                  .pgpolicy      = GROUP_BY_PRIO,
>>                  .pgfailback    = -FAILBACK_IMMEDIATE,
>>                  .prio_name     = PRIO_ALUA,
> 
> Ref: https://github.com/opensvc/multipath-tools/issues/6
> 
> The question is on which basis IBM came up with this recommendation.
> 5 (aka 25s) is a rather low value. Some users may encounter unpleasant
> surprises if we change the default this way, as it used to be infinite
> before.
> 
> Using 5, the IBS 2145 would have the 2nd-lowest default in hwtable.c
> after Dell PowerStore (3). Symmetrix has 6; all other arrays default to
> 10 or higher, many default to "queue".
> 
> Observing that the above is the documentation for the *Flashsystem*
> 9200,  I consider it likely that the value ".no_path_retry = 5" would
> apply to flash-based IBM storage products, but not to the older
> products such as the V7000, which unfortunately use the same device ID.
> 
> It'd be helpful if someone from IBM could jump in here...
> 
> Pondering the pros and cons, I vote for keeping the current defaults
> for now.

+1

I think this depends on host and workload requirements and maybe other things. 
There might not be one simple answer.

FWIW, from a zfcp point of view: 
https://public.dhe.ibm.com/software/dw/linux390/lvc/zFCP_Best_Practices-BB-Webcast_201805.pdf#page=19
Distributed/parallel file systems with shared volumes might have their own 
requirement.
YMMV

We also have our opinion on dev_loss_tmo and fast_io_fail_tmo, but that's a 
different story 
[https://public.dhe.ibm.com/software/dw/linux390/lvc/zFCP_Best_Practices-BB-Webcast_201805.pdf#page=18].

-- 
Mit freundlichen Gruessen / Kind regards
Steffen Maier

Linux on IBM Z and LinuxONE

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^ permalink raw reply	[flat|nested] 3+ messages in thread

end of thread, other threads:[~2021-08-31  7:25 UTC | newest]

Thread overview: 3+ messages (download: mbox.gz / follow: Atom feed)
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2021-08-25 22:24 [dm-devel] [PATCH] multipath-tools: update no_path_retry value for IBM/2145 Xose Vazquez Perez
2021-08-26  6:47 ` Martin Wilck
2021-08-30 16:57   ` Steffen Maier

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