Am 27.08.19 um 14:40 schrieb Hans van Kranenburg:
> On 8/27/19 11:14 AM, Swâmi Petaramesh wrote:
>> On 8/27/19 8:52 AM, Qu Wenruo wrote:
>>>> or to use the V2 space
>>>> cache generally speaking, on any machine that I use (I had understood it
>>>> was useful only on multi-TB filesystems...)
>>> 10GiB is enough to create large enough block groups to utilize free
>>> space cache.
>>> So you can't really escape from free space cache.
>>
>> I meant that I had understood that the V2 space cache was preferable to
>> V1 only for multi-TB filesystems.
>>
>> So would you advise to use V2 space cache also for filesystems < 1 TB ?
>
> Yes.
>
This makes me wonder if it should be the default?
This thread made me check on my various BTRFS volumes and for almost all of
them (in different machines), I find cases of
failed to load free space cache for block group XXXX, rebuilding it now
at several points during the last months in my syslogs - and that's for
machines without broken memory, for disks for which FUA should be working fine,
without any unsafe shutdowns over their lifetime, and with histories as short
as only having seen 5.x kernels.
So if this may cause harmful side effects, happens without clear origin, and v2
is safer due to being CoW,
I guess I should switch all my nodes to v2 (or this should become the default
in a future kernel?).
Cheers,
Oliver
