Justin Piszcz schrieb:
>
>
> On Mon, 24 Sep 2007, Ralf Gross wrote:
>
> >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
> >
>
> I find that to be the case with SW RAID (defaults are best)
>
> Although with 16 drives(?) that is awfully slow.
>
> I have 6 SATA's I get 160-180 MiB/s raid5 and 250-280 MiB/s raid 0 (sw
> raid).
>
> With 10 raptors I get ~450 MiB/s write and ~550-600 MiB/s read, again
> XFS+SW raid.
Hm, with the different HW-RAIDs I've used so far (easyRAID,
Infortrend, internal Areca controller), I always got 160-200 MiB/s
read/write with 7-15 disks. That's one reason why I asked if there are
some xfs options I could use for better performance. But I guess fs
options won't boost performance that much.
Ralf
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