On Wed, Dec 4, 2013 at 9:20 AM, Leon Fauster leonfauster@googlemail.com wrote:

Am 04.12.2013 um 17:08 schrieb John Doe jdmls@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-a... 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/...

"Red Hat recommends batch discard operations ..." (fstrim)

LF

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-li...

Quote: "This is the most interesting part. Most people simply add the option “discard” in the mounting options at /etc/fstab. However, this means that every time you delete a file, the OS will be reporting in real-time to the SSD which blocks were occupied by that file and are not longer in use, and then the SSD will have to perform a defragmentation and deletion of those internal blocks, operation which will take an amount of time higher than desired.

In order to optimize the performance of the SSD, I strongly advise you to avoid doing the TRIM operation in real time (whenever a file is deleted) because you would be putting an unnecessary extra amount of work over the SSD. In other words: You should not enable the discard option in fstab.

Instead, what I recommend is to run a script periodically to tell the SSD which blocks are free with the command fstrim. Doing this operation daily or weekly is more than enough. This way we do not lose any performance due to TRIM when deleting files and we periodically keep informed the SSD about the free blocks."

Akemi

Am 04.12.2013 um 19:20 schrieb Akemi Yagi amyagi@gmail.com:

On Wed, Dec 4, 2013 at 9:20 AM, Leon Fauster leonfauster@googlemail.com wrote:

...

Am 04.12.2013 um 17:08 schrieb John Doe jdmls@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-a... 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/...

"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-li...

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/...

"The only DM targets that do not support discards are dm-snapshot, dm-crypt, and dm-raid45."

maybe with the next minor release?

-- LF

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@googlemail.com wrote:

Am 04.12.2013 um 19:20 schrieb Akemi Yagi amyagi@gmail.com:

...

On Wed, Dec 4, 2013 at 9:20 AM, Leon Fauster leonfauster@googlemail.com wrote:

...

Am 04.12.2013 um 17:08 schrieb John Doe jdmls@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-a... 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/...

"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-li...

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/...

"The only DM targets that do not support discards are dm-snapshot, dm-crypt, and dm-raid45."

maybe with the next minor release?

-- LF

---

CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos

On 6 December 2013 12:53, Nux! nux@li.nux.ro wrote:

On 06.12.2013 12:20, Cian Mc Govern wrote:

...

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.

Discard has been supported in EL6 for a long time now!

For dm-crypt I mean.

-- Sent from the Delta quadrant using Borg technology!

Nux! www.nux.ro _______________________________________________ CentOS mailing list CentOS@centos.org http://lists.centos.org/mailman/listinfo/centos