[CentOS] SSD support in C5 and C6

[Wade Hampton]

>From what I have read, TRIM can also be done on demand
for older systems or file systems that are not TRIM aware.
For CentOS 5.x, a modified hdparm could be used to send
the TRIM comamnd to the drive.  Anyone have experience
with this?
--
Wade Hampton


On Fri, Jul 19, 2013 at 1:05 PM, John R Pierce <pierce at hogranch.com> wrote:

> On 7/19/2013 8:48 AM, Wade Hampton wrote:
> > I found lots of references to TRIM, but it is not included
> > with CentOS 5.  However, I found that TRIM is in the
> > newer hdparm which could be build from source,
> > but AFIK is not included with CentOS 5 RPMS.  That way,
> > one could trim via a cron job?
>
>
> trim is done at the file system kernel level.    essentially, its a
> extra command to the disk telling it this block is complete and the rest
> of it 'doesn't matter' so the drive doesn't need to actually store it.
>
>
> On 7/19/2013 7:10 AM, Alexander Arlt wrote:
> > Hm. I'm not sure, if I'd go with that. In my understanding, I'd just buy
> > something like a Samsung SSD 840 Pro (for not using TLC) and do a
> > overprovisioning of about 60% of the capacity. With the 512GiB-Variant,
> > I'd end up with 200GiB netto. By this way, I have no issues with TRIM or
> > GC (there are always enough empty cells) and wear leveling is also a
> > non-issue (at least right now...).
>
> those drives do NOT have 'supercaps' so they will lose any recently
> written data on power failures.   This WILL result in corrupted file
> systems, much the same as using a RAID controller with write-back cache
> that doesn't have a internal RAID battery.
>
>
>
> --
> john r pierce                                      37N 122W
> somewhere on the middle of the left coast
>
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