[clug] Kernel without initramfs

steve jenkin sjenkin at canb.auug.org.au
Sat Mar 28 02:13:14 GMT 2009

Daniel Pittman wrote on 28/3/09 10:07 AM:

> That varies, as the other thread says, a lot based on your SSD.
> Notably, the Intel SSDs use a block map, and combine multiple small
> writes into a single large write with little regard for the LBA of the
> individual blocks.


> Regards,
>         Daniel
> At least, in so far as filesystems written by Ted go. :)

I thought the thread originator was using a CF+IDE adaptor, not an SSD unit.

AFAI-can-see the only logical difference between the two flash devices
is the connectors - but chip manufacturers might make very different
designs & trade-offs.

I'm suspecting there is more difference between manufacturers and
product lines that between generic {CF vs SSD}.

Anyone know about this?


PS: I read a piece by consultant/journalist/salesman Robin Harris in
2006 talking about using 100K-cycle Single-Level NAND flash SSD in
'enterprise' devices for tasks such as writing 2Kb log-file blocks.

I've wondered if he got it right or was off in a hype-bubble.

"Let’s say you want to use it for a log file running 2k I/Os (question:
do systems still do 2k I/Os? readers please help). So a 32 GB drive has
16,384,000 2k locations, which multiplied by 100,000 equals 1.64
trillion 2k I/Os. So if your server is updating the log file 500 times
per second, which would be a reasonably busy server, you’d be doing
1,800,000 RW cycles per hour. So your 32 GB flash drive would last
910,222 hours or almost 104 years of 24 hour a day operation.

"At 1,000 IOPS, then 52 years. 1,000 8k IOPS, then 12 years and change.
10,000 8k IOPS then 14 months. All for, I estimate, based on chip prices
for about $1k per drive, or about 1/40th the price of a standard
RAM-based SSD. So call me crazy, but I say flash is set to conquer the
esoteric world of high-performance SSDs.

Steve Jenkin, Info Tech, Systems and Design Specialist.
0412 786 915 (+61 412 786 915)
PO Box 48, Kippax ACT 2615, AUSTRALIA

sjenkin at canb.auug.org.au http://members.tip.net.au/~sjenkin

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