Re: SSD for Centos SWAP /tmp & /var/ partition

[Emmanuel Noobadmin <centos.admin@xxxxxxxxx>]

On 5/26/11, Simon Matter <simon.matter@xxxxxxxxx> wrote:
>> On 5/26/11, Kevin K <kevink1@xxxxxxxxxx> wrote:
>>> Though thumb drives are flash, they tend to use a slower flash than what
>>> is
>>> used in hard drive replacement units.
>>
>> No actual industry facts for this, but I think the Flash used in thumb
>> drives are not really any slower by nature/design. This is because I
>> see that the fastest SSD currently tend to use 8 channel controllers
>> for 200+ MB/s performance which translate to 20~30MB/sec per channel.
>
> There is quite a difference between common USB flash drives and SSDs. SSDs
> are supposed to replace a HDD while USB drives are not designed for it.
> One difference is the type of wear leveling, also documented here
> http://en.wikipedia.org/wiki/Wear_leveling

Just to point out, that articles says the wear leveling used in USB
flash drives result in faster performance which runs counter to
Kevin's original claim of "slower flash". ;)

The key thing I was pointing out is that, the underlying Flash
technology doesn't appear to be different in SSD Hard disks or USB
flash drives.

The key differentiating component always seems to be the controller,
i.e. 8-channel on the SATA Flash vs 1 channel on the USB Flash and the
controller using different write leveling algorithm to map logical
addresses to actual physical cells.

So the difference between a USB Thumbdrive and a USB SSD is like the
difference between an eSATA single disk enclosure and an eSATA two
disk RAID 0 enclosure.
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