Brian LaMere wrote:
yes, that dd statement will work, but you probably want to increase
your block size (bs=?)
there's a sweet spot one has to find for all systems, but since you're
only going to do it once you'll just have to guess. I find best luck
starting at approx half the smallest amount of cache in the entire
chain. Of course, I only really do it on scsi...
The best size to use is a multiple of the Linux cache page size (4096
bytes) but also a multiple of the device packet size.
ATA devices (both PATA and SATA) work best with either an 8 kbyte or 16
kbyte blocksize; SCSI and fibrechannel work best with a 32 or 64 kbyte
block size.
You definitely don't want to do anything but multiples of 4096 bytes;
4096 bytes is the size of a page of disk cache. Reads and (especially)
writes of a size that is not a multiple of 4k will result in the block
layer causing a bunch of extra seeking to fill misaligned cache pages.
-Kelsey
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