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Old 04-13-2011, 04:28 PM
John Doe
 
Default CentOS on SSDs...

Hi,

I was just wondering if there are specific steps to take to install CentOS on
SSDs...
By example, no swap partition?
Format with a flash fs?
Sysctl parameters?

Thx,
JD
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Old 04-13-2011, 05:08 PM
Jim Angell
 
Default CentOS on SSDs...

On 04/13/2011 10:28 AM, John Doe wrote:
> Hi,
>
> I was just wondering if there are specific steps to take to install CentOS on
> SSDs...
> By example, no swap partition?
> Format with a flash fs?
> Sysctl parameters?
>
> Thx,
> JD
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
Hi JD,

I've always used the default partition layout when installing on an
SSD. I haven't had any problems with CentOS 5.5, haven't tested with
5.6 yet.

- Jim

--
Regards

Jim Angell
UNIX Administrator
Cade Network Operations
College Of Engineering
Phone: (801)-581-7551


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Old 04-13-2011, 05:08 PM
Jim Nelson
 
Default CentOS on SSDs...

On 4/13/2011 12:28 PM, John Doe wrote:
> Hi,
>
> I was just wondering if there are specific steps to take to install CentOS on
> SSDs...
> By example, no swap partition?
> Format with a flash fs?
> Sysctl parameters?
>
> Thx,
> JD

We're running an nginx frontend on SSDs right now - don't bother with things like JFFS2, they're intended for SoC distros that have
raw flash chips memory-mapped to the controller. Most of that intelligence is handled by the SSD controller.

CentOS 5 does not have TRIM capability - I'm not sure if CentOS 6 will or not, though. The most important part of setting up SSDs on
a server is to mount all the filesystems with the noatime option - that reduces the filesystem writes tremendously. Having a good
controller is equally important - don't run them on a $25 SATA card.

And, since memory (up to a point) is cheaper than SSDs, fill the box with memory sticks. Keep a swap partition, but put in far more
memory than you think you will need, and that way you won't hit swap unless the excrement really hits the air mover. At least,
that's how we're doing it.

--
Jim Nelson
Systems Administrator, Broadtime
(888) 582-3229
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Old 04-13-2011, 09:10 PM
Ljubomir Ljubojevic
 
Default CentOS on SSDs...

John Doe wrote:
> Hi,
>
> I was just wondering if there are specific steps to take to install CentOS on
> SSDs...
> By example, no swap partition?
> Format with a flash fs?
> Sysctl parameters?
>
> Thx,
> JD
> _______________________________________________
> CentOS mailing list
> CentOS@centos.org
> http://lists.centos.org/mailman/listinfo/centos
>
>
Please read this:
http://plone.lucidsolutions.co.nz/linux/io/using-centos-5.2-stateless-linux-support-on-a-flash-based-root-filesystem#section-13
if you want to reduce writings to the SSD (read-only root, etc.)

Ljubomir
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Old 04-14-2011, 09:22 AM
Michael Simpson
 
Default CentOS on SSDs...

On 13 April 2011 18:08, Jim Nelson <jim@broadtime.com> wrote:
> On 4/13/2011 12:28 PM, John Doe wrote:
>> Hi,
>>
>> I was just wondering if there are specific steps to take to install CentOS on
>> SSDs...
>> By example, no swap partition?
>> Format with a flash fs?
>> Sysctl parameters?
>>
>> Thx,
>> JD
>
> We're running an nginx frontend on SSDs right now - don't bother with things like JFFS2, they're intended for SoC distros that have
> raw flash chips memory-mapped to the controller. Most of that intelligence is handled by the SSD controller.
>
> CentOS 5 does not have TRIM capability - I'm not sure if CentOS 6 will or not, though. The most important part of setting up SSDs on
> a server is to mount all the filesystems with the noatime option - that reduces the filesystem writes tremendously. Having a good
> controller is equally important - don't run them on a $25 SATA card.
>
> And, since memory (up to a point) is cheaper than SSDs, fill the box with memory sticks. Keep a swap partition, but put in far more
> memory than you think you will need, and that way you won't hit swap unless the excrement really hits the air mover. *At least,
> that's how we're doing it.
>
> --
> Jim Nelson
> Systems Administrator, Broadtime
> (888) 582-3229

The MTBF of SSDs and combined with the wear leveling that they use
means that you don't need to worry about them breaking any more. The
more important point is that without TRIM the performance will
significantly degrade as the drive gets used.
I have been using an SSD in a laptop for the last 3 years with CentOS
5 and it works really well and even though the performance did drop it
is still faster than the drive i replaced (very old laptop)
wrt TRIM
This is enabled by default on swap with RHEL 6 but is only available
for other partitions if they are native ext4 and only if you use the
discard option. It therefore won't be switched on for LVM partitions
or any partition or drive using md .
Worth checking that your drive does support it before switching it on.

regards

mike
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Old 04-15-2011, 09:15 AM
John Doe
 
Default CentOS on SSDs...

Thanks to all for the info.

Guess I will either keep CentOS 5 and have to compile my own kernel for the
discard option; or wait for CentOS 6...

Thx,
JD
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CentOS@centos.org
http://lists.centos.org/mailman/listinfo/centos
 

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