On 8/26/21 8:47 AM, Martin Wilck wrote:
^^^^^^^
It is never too late!
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@xxxxxxxx>
Cc: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
Cc: Christophe Varoqui <christophe.varoqui@xxxxxxxxxxx>
Cc: DM-DEVEL ML <dm-devel@xxxxxxxxxx>
Signed-off-by: Xose Vazquez Perez <xose.vazquez@xxxxxxxxx>
---
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
Some history:
first commit 3eb8c380a :
{
/* IBM SAN Volume Controller */
.vendor = "IBM",
.product = "2145",
.getuid = DEFAULT_GETUID,
.getprio = "mpath_prio_alua /dev/%n",
.features = "1 queue_if_no_path",
.hwhandler = DEFAULT_HWHANDLER,
.selector = DEFAULT_SELECTOR,
.pgpolicy = GROUP_BY_PRIO,
.pgfailback = -FAILBACK_IMMEDIATE,
.rr_weight = RR_WEIGHT_NONE,
.no_path_retry = NO_PATH_RETRY_UNDEF,
.minio = DEFAULT_MINIO,
.checker_name = TUR,
},
NO_PATH_RETRY_UNDEF was removed in b7c3cf014 because it was the default value,
and later "1 queue_if_no_path" was replaced by NO_PATH_RETRY_QUEUE in 87ea76f99
IBM docs recommends:
no_path_retry 5 # or no_path_retry "fail" for some current linux distros
IBM Storage FlashSystem 5200, 5000, 5100, Storwize V5100 and V5000E:
https://www.ibm.com/docs/en/flashsystem-5x00/8.6.x?topic=system-settings-linux-hosts
IBM Storage FlashSystem 7300, 7200 and Storwize V7000:
https://www.ibm.com/docs/en/flashsystem-7x00/8.6.x?topic=system-settings-linux-hosts
IBM FlashSystem V9000:
https://www.ibm.com/docs/en/flashsystem-v9000/8.3.x?topic=system-settings-linux-hosts
IBM Storage FlashSystem 9500, 9200 and 9100:
https://www.ibm.com/docs/en/flashsystem-9x00/8.6.x?topic=system-settings-linux-hosts
Therefore, we should change this value.
