PC GAMESS/Firefly-related discussion club

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Slawomir Janicki
slawomir.janicki@comcast.net

There are two issues to consider:

- SSD drives read in 4kb blocks, but write in 512kb blocks. The controller has to manage this, but careful adjustment of the record size in Firefly will help for sure.
- the MLC NAND gates can fail after about 10,000 writes, the SLC NAND gates can fail after about 100,000 writes. Again, the controller has to manage the lifespan of the drive.

It seems that the the SLC drives from Intel X-25E have the upper hand over Intel X-25M (second generation) MLC drives, which are better than most of the other MLC drives. However, they can still loose 15% of performance after some use. Under Windows 7/2008 R2 these drives can use the TRIM instruction to "defragment" themselves and gain back most of this loss. However under XP/Vista/2008 R1 the the dives with the Indilinx need a command prompt utility which may or may not be reliable.

There are new drives coming to market with better prices than Intel. The Solid 2 series is built based on the same flash as Intel X-25M.

The best buys seem to be the Intel X-25M and OCZ Vertex II. The "do not buy" label belongs to Samsung, Western Digital, and anything OEM. Which means, don't upgrade your Dell, Apple, Lenovo, or HP to SSD, you are likely to get Samsung junk.

The good drives saturate the 3Gb SATA bus on sequential read, so I am thinking that each drive can service four cores of i7 920 or 860. I am sure that getting the top performance will need tweaking with the record sizes in Firefly.

Slawomir


On Tue Nov 17 '09 6:57pm, Thomas Patko wrote
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>Dear PC GAMESS / Firefly Users:

>Does anyone have any first hand experience using any of the newer solid state disks (SSD) as temporary directories for I/O intensive jobs such as MP2?  While it is generally recommended to only use one traditional HDD for each temporary directory (per core) I wonder if the SSD can support multiple temporary directories for disk intensive I/O jobs as they should perform better for simultaneous read/write operations.  If so, how many temporary directories (cores) can one SSD handle simultaneously without significant slowdown (like traditional HDD)?

>Any manufacturer recommendations and timing reports would be appreciated.  While the SSD prices have come out of the stratosphere it seems that the SSD are still rather expensive so I am weighing the cost options, although space becomes a consideration for machines with very many cores.

>I am also interested in any first hand / anecdotal accounts about MTBF (other than what the manufacturer report for general use versus this significantly more severe service Firefly use).

>Cheers,

>Thomas