Can't mount partitions with soft-updates enabled with asyncoption

[Darren Pilgrim]

From: Matthias Buelow
> Lefteris Tsintjelis <lefty at ene.asda.gr> writes:
> 
>> I am not sure if I do something wrong here or it is suppose
>> to work that way but the async option doesn't seem to work
>> for partitions that have soft-updates turned on. Can someone
>> please clarify the difference and if the speed difference (if
>> any) is significant when using the async option instead of
>> the soft-updates for cases such as the /usr/obj or as a squid
>> data storage? Is async preferred over soft-updates when data
>> loss is not a big issue?
> 
> With softupdates, everything is asynchronous so the option
> doesn't make sense.  For improving squid filesystem
> performance, have you mounted the partition with noatime? That
> might make some difference.

No.  With softupdates, file writes are asynchronous, but writes to
filesystem structures (metadata) are synchronous to prevent filesystem
corruption if the machine crashes.  The async mount option writes both
asynchronously.  You can't use the async mount option on a volume with
softupdates turned on because the two options are mutually exclusive.

[ Note: -stable trimmed for relevance. ]