ZFS: How to enable cache and logs.

[krad]

2011/5/12 Šimun Mikecin <numisemis at gmail.com>

>
> On 12. svi. 2011., at 08:44, Daniel Kalchev wrote:
>
> > On 12.05.11 05:26, Danny Carroll wrote:
> >>
> >>  - Don't use SSD for the Log device.  Write speed tends to be a problem.
> > It all depends on your usage. You need to experiment, unfortunately.
>
> What is the alternative for log devices if you are not using SSD?
> Rotating hard drives?
>
> AFAIK, two factors define the speed of log device: write transfer rate and
> write latency.
> You will not find a rotating hard drive that has a write latency anything
> near the write latency of even a slowest SSD you can find on the market.
> On the other hand, only a very few rotating hard drives have a write
> transfer rate that can be compared to SSD's.
>
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ive seen an interesting article using 2x ram disks on two separate computers
(UPS backed) shared out via iscsi over a high speed network. It had very
successful results. Sounds a bit brave in a production environment to me
though