I have 2GB On this machine. For me, 8192 seems to be the sweet spot, I
will probably keep it at 8mb.
On Fri, 23 Feb 2007, Jason Rainforest wrote:
Hi Justin,
I'm not a RAID or kernel developer, but .. do you have enough RAM to
support a 32mb stripe_cache_size?! Here on my 7*250Gb SW RAID5 array,
decreasing a stripe_cache_size of 8192 to 4096 frees up no less than
120mb of RAM. Using that as a calculation tool, a 32mb stripe_cache_size
would require approximately 960mb of RAM! My RAID box only has 1Gb of
RAM, so I'm not game to test such a thing. Others on these lists would
definitely have a good idea on what's happening :-)
Cheers,
Jason
On Fri, 2007-02-23 at 06:41 -0500, Justin Piszcz wrote:
Each of these are averaged over three runs with 6 SATA disks in a SW RAID
5 configuration:
(dd if=/dev/zero of=file_1 bs=1M count=2000)
128k_stripe: 69.2MB/s
256k_stripe: 105.3MB/s
512k_stripe: 142.0MB/s
1024k_stripe: 144.6MB/s
2048k_stripe: 208.3MB/s
4096k_stripe: 223.6MB/s
8192k_stripe: 226.0MB/s
16384k_stripe: 215.0MB/s
When I tried a 32768k stripe, this happened:
p34:~# echo 32768 > /sys/block/md4/md/stripe_cache_size
Connection to p34 closed
I was able to Alt-SysRQ+b but I could not access the console/X/etc, it
appeared to be frozen.
FYI.
Justin.
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