Re: SSD

[Michal Suchanek <hramrach%centrum.cz@localhost>]

2009/7/12 Shin'ichiro TAYA <taya%ba2.so-net.ne.jp@localhost>:
> Hi, I'm going to setup a NetBSD machine as IP firewall, mail gateway,
> www server.
> I'm planinng to use SSD because of low noise and low power consumption.
> I've purchased following one.
> - Transcend, TS32GSSD25S
> http://www.transcendusa.com/support/dlcenter/datasheet/SSD25S-JMI%20Datasheet%20v1.08.pdf
>
> I've alreay installed -current on it and measured disk performance with
> bonnie++.
> But write performance is miserablely slow.
> (one reason is my SSD is most cheep range, but...)
>

Slow write performance tends to be the major factor behind slow
adoption of SSDs it seems. However. it should be no problem for a
firewall or low traffic mail server, especially if you use techniques
that are used to limit disk writes in laptops to save power. In this
case limiting disk writes should limit the slowdown caused by the low
write performance. Given the system has enough memory it can buffer a
lot of data without the need for the system to slow down while waiting
for disk writes.

Since the datasheet says that the disk has dynamic wear leveling it
should be resistant to journalling, unlike real hardrives. However,
journalling still means double writes of some data, additional
slowdawn and more wear of the flash storage. It means shorter boot
times after a crash or power outage, though.

HTH

Michal