Mailinglist Archive: opensuse (671 mails)

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Re: [opensuse] Idle Time Garbage Collection (ITGC) On (openSUSE) Linux
On Sunday June 12 2011, Randall R Schulz wrote:
On Saturday June 11 2011, Cristian Rodríguez wrote:
El 12/06/11 00:57, Randall R Schulz escribió:
Hi,

My next question relating to using SSDs on openSUSE is whether
they enable or implement the so-called Idle Time Garbage
Collection used by SandForce SSD chips (such as the SandForce
1222 chips on the RevoDrive x2 card I bought).

afaics, "Idle Time Garbage Collection" is implemented in the
controller.

Yes, that much I understood. I just couldn't see how it could "garbage
collect" anything if the OS didn't tell it which logical sectors it was
actually using.


Nothing I've found has made it clear whether this is something
that requires OS / filesystem support, but the descriptions I've
found (which have been very sketchy) suggest filesystem support
is required.

TRIM needs support in the filesystem, ext4 has a support for it,
using the "discard" mount option, which is apparently on its
infancy.

Cheers.

Thanks.

The only thing I can't make sense of is how the controller knows
which sectors (or pages or blocks or whatever they call them on SSDs)
are being used for file contents and which are not without filesystem
interaction. One description I found said the controller "asks the
operating system" if a block is in use.

After reading a rather contentious thread on www.ocztechnologyforum.com
[1] I think I understand, at least in very rudimentary terms, how the
ITGC thing works.


...


[1] <http://www.ocztechnologyforum.com/forum/showthread.php?60219-How-s-GC-gonna-work-for-RAID>


Randall Schulz


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