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Long-term performance analysis of Intel Mainstream SSDs


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#1 Nvyseal

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Posted 15 February 2009 - 01:00 AM

When the Intel X25-M series of solid state drives hit the market last year, there was little debate that they were easily the best performing MLC (multi-level cell) offerings to date. The one area in which they blew away the competition was with write speeds — initial reviews showed consistent 80MB/s results. However, a new article over at PC Perspective that looks at Intel X25-M performance over a period of time shows that write speeds are dramatically reduced from everyday usage patterns. Average write speeds are shown to drop to half (40MB/s) or less in the worst cases, though the author does describe ways that users can recover some of the original drive speed using standard HDD testing tools


Quote

While Intel reportedly has something in the works, there is currently no ‘easy’ way to defragment the sub-block level fragmentation that occurs as a result of write combining. In addition, we found that running the Windows defragmenter on the X25-M would rapidly Swiss Cheese the crap out of it, defeating the purpose entirely. All is not lost, however, as the ATA spec is being updated to include special commands such as “TRIM”, “DISCARD”, and “UNMAP” (a SCSI command). The new protocol lingo will let the Operating System tell the SSD when areas are no longer in use, such as when files are deleted. This will speed up the process of writing data to flash blocks no longer containing valid data, as the wear leveling routine doesn’t have to play musical chairs with data that is no longer relevant.

Windows 7 will support some variation of these commands, and firmware flashable drives like the X25-M should have the ability to be brought up to speed as well. This will not completely solve the problem – It falls short on some RAID configurations (i.e. RAID 5), since all data must remain ‘valid’ for parity calculations to work properly in the case of a drive failure. Data recovery also becomes more complicated, since deleted files could be overwritten by the wear leveling routine even if the OS did not specifically write over the addresses where those files were originally stored.

Workaround #1: Change your usage pattern

Until Intel tweaks their write combining algorithms and revises their released firmware, there are ways to minimize your chances of falling into the fragmentation black hole. Here are some things to avoid:

* Disk partitions not properly aligned with flash block boundaries (to be covered in another article).
* Heavy temporary file activity (think temporary internet files).
* Heavy page / swap activity.
* Applications that write random small chunks, even within a larger file (i.e. BitTorrent / Steam).
* Running *any* disk defragment utility (DON’T DO IT!).

Read the full article HERE

I wonder if all SSD's are similar to this?

#2 m.oreilly

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Posted 15 February 2009 - 01:12 AM

hehe, intel are a bit late to the table w/this info, though it's nice they finally admit it. ocz has been researching this for a time, and i had read up on this months ago, before ever thinking of using ssd full time, 24/7. yep, without proper care of your partition and changes in habits as well as os routines, it 's not the 'out of the box' experience to have them work efficiently while keeping the system from knowing there ain't no spinning disk in there...diskeeper 2009 has a bundled app called "hyperfast", which can be set up to take care of ssd only storage, and is quite effective in dealing with unused space/fragmentation (kinda a "soft" defrag, helping out the drive's wear leveling routine). though maybe not for everyone atm, it just takes a little effort to keep a healthy ssd storage option going strong (though i have no info re parity arrays with the current crop of drives. kinda another thing altogether).

#3 stormrosson

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Posted 15 February 2009 - 01:50 AM

:giggle: ummmmmmmmmmmmmmm yep what MO said :talker:




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