[CentOS] To discard... or not to discard...

Fri Dec 6 12:20:15 UTC 2013
Cian Mc Govern <cian at cianmcgovern.com>

I believe discard support is only available since kernel 3.1.

It'd be great if it was added to RHEL 6 - I'm using Fedora 18 on any
machines that require it in the meantime.

Cian.

On 4 December 2013 21:59, Leon Fauster <leonfauster at googlemail.com> wrote:
> Am 04.12.2013 um 19:20 schrieb Akemi Yagi <amyagi at gmail.com>:
>> On Wed, Dec 4, 2013 at 9:20 AM, Leon Fauster <leonfauster at googlemail.com> wrote:
>>> Am 04.12.2013 um 17:08 schrieb John Doe <jdmls at yahoo.com>:
>>>> I just recently read a post about SSD triming (discard vs fstrim):
>>>>
>>>> http://www.howtogeek.com/176978/ubuntu-doesnt-trim-ssds-by-default-why-not-and-how-to-enable-it-yourself/So far I used discard on all my SSDs.
>>>> Now I am wondering if it is really worth it to switch them all to a crontabed fstrim...
>>>> Anyone made the switch yet?
>>>
>>> https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html-single/Storage_Administration_Guide/#idm34358800
>>>
>>> "Red Hat recommends batch discard operations ..." (fstrim)
>>>
>>
>> In addition to the RH doc referenced by LF, I found this web page useful:
>>
>> http://blog.neutrino.es/2013/howto-properly-activate-trim-for-your-ssd-on-linux-fstrim-lvm-and-dmcrypt/
>
>
> interesting article. it shows the passthrough of the discard option with
> dm-crypt involved. rhel seems to not provide such "dm-crypt/trim" support.
>
> https://access.redhat.com/site/documentation/en-US/Red_Hat_Enterprise_Linux/6/html/Storage_Administration_Guide/ch-ssd.html#ssddeploy
>
> "The only DM targets that do not support discards are dm-snapshot, dm-crypt, and dm-raid45."
>
> maybe with the next minor release?
>
> --
> LF
>
>
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