On 12/28/2016 03:14 PM, Raman Gupta wrote:
On 12/28/2016 04:24 PM, Rick Stevens wrote:
> On 12/28/2016 10:33 AM, Raman Gupta wrote:
>> I would like to change the cache mode of an existing lvm cache volume.
>>
>> I see the following in the man page:
>>
>> `With the --cachemode option, the cache mode can be set when creating
>> a cache LV, or changed on an existing cache LV.`
>>
>> However, it does not seem to work:
>>
>> # lvs -o cache_mode vg_raid10/lv_var
>> CacheMode
>> writethrough
>> # lvconvert --cachemode writeback vg_raid10/lv_var
>> # lvs -o cache_mode vg_raid10/lv_var
>> CacheMode
>> writethrough
>>
>> (Fedora 23, 4.8.14)
>>
>> The `lvconvert` command produces no output, and there is nothing in
>> dmesg or the journal.
>
> Have you tried adding the "-v" or "--verbose" flags to see if
there
> is an issue?
No change:
# lvconvert --verbose --cachemode writeback vg_raid10/lv_var
# lvs -o cache_mode vg_raid10/lv_var
CacheMode
writethrough
Looking at the man page for lvconvert (at least under F24 and F25), the
"--type cache" flag is necessary to specify the "--cachemode
writeback"
option:
# lvconvert --verbose --type cache --cachemode writeback vg_raid10/lv_var
You might have to specify the cache pool stuff as well. Not sure. I've
never done this.
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