[geeks] Understanding ZFS performance (maybe) part 2 - NFS performance solved for $100 bucks

[Joshua Boyd]

On Aug 10, 2009, at 7:38 PM, Patrick Giagnocavo wrote:

> I went ahead and bought the Gigabyte "i-Ram" from Amazon.com and threw
> in 2x 256MB PC2700 non-ECC I had lying around, to give me a 512MB  
> NVRAM
> disk.
>
> I then installed it in the fileserver, played around with the disks a
> bit, and as it turns out, there are some problems even now,  
> removing the
> log device from a zpool.  Since there was nothing of importance, I  
> blew
> it away and recreated it as a mirror of 2x 1TB drives then added the
> 512MB ramdisk as the log device.
>
> WOW.
>
> I am now getting 90MB/s or higher peak write speeds over gigabit  
> NFS, up
> from the previous 5MB to 8MB/s write speeds.
>
> So it is now totally usable for serving up VMware ESX VMs.
>
> Pros:
> does not take up a SATA drive bay slot
>
> has rechargeable lithium battery that should last for several hours or
> longer (if your server is in production you will notice the  
> downtime and
> thus it will be long enough)
>
> cheaper than Intel SLC SSD (about $300 currently), though the Intel is
> larger in capacity
>
> Cons of the card:
>
> for about $200 more you can get a SATA SSD from Intel that has higher
> capacity
>
> the card is oversized and may not fit in tight spaces like certain 1U
> chassis
>
> 1.5Gbps (SATA-I) only.
>
> Overall, I am pleased with the performance improvement and will  
> keep it.
>  Given the apparent speed increase, my next system for file serving  
> will
> definitely have SSDs in it, probably mirrored.

You probably don't want to spend the money, but I'd love to see you  
directly compare this against a flash drive.  Maybe you could look at  
the OCZ Vertex drives, or even the cheaper (and probably slower)  
Emphase SATA modules from logic supply (1 gig for $31).

I suspect that the product you did get gives us a good idea how Sun's  
Logzilla drive would improve things.