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

[Patrick Giagnocavo]

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.

--Patrick