Justin Piszcz schrieb:
>> A bit ot: will I waste space on the RAID device with a 256K chunk size
>> and small files? Or does this only depend on the block size of the fs
>> (4KB at the moment).
>
> That's a good question, I believe its only respective of the filesystem
> size, but will wait for someone to confirm, nice benchmarks!
>
> I use a 1 MiB stripe myself as I found that to give the best performance.
256KB is the largest chunk size I can choose for a raid set. BTW: the HW-RAID
is an Overland Ultamus 4800.
The funny thing is, that performance (256KB chunks) is even better without
adding any sw/su option to the mkfs command.
mkfs.xfs /dev/sdd1 -f
Sequential Reads
File Blk Num Avg Maximum Lat% Lat% CPU
Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
----- ----- --- ------ ------ --------- ----------- -------- -------- -----
20000 4096 1 208.33 23.81% 0.055 49.55 0.00000 0.00000 875
20000 4096 2 199.48 43.72% 0.116 376.85 0.00000 0.00000 456
Random Reads
File Blk Num Avg Maximum Lat% Lat% CPU
Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
----- ----- --- ------ ------ --------- ----------- -------- -------- -----
20000 4096 1 2.83 0.604% 4.131 38.81 0.00000 0.00000 469
20000 4096 2 4.53 1.700% 4.995 67.15 0.00000 0.00000 266
Sequential Writes
File Blk Num Avg Maximum Lat% Lat% CPU
Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
----- ----- --- ------ ------ --------- ----------- -------- -------- -----
20000 4096 1 188.15 42.98% 0.047 7547.93 0.00027 0.00000 438
20000 4096 2 167.76 76.89% 0.100 7521.34 0.00078 0.00000 218
Random Writes
File Blk Num Avg Maximum Lat% Lat% CPU
Size Size Thr Rate (CPU%) Latency Latency >2s >10s Eff
----- ----- --- ------ ------ --------- ----------- -------- -------- -----
20000 4096 1 2.08 0.869% 0.016 0.13 0.00000 0.00000 239
20000 4096 2 1.80 1.501% 0.020 6.28 0.00000 0.00000 12
Ralf
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