Date: Tue, 03 Jun 2014 11:56:19 +0200 From: Frank Broniewski <brfr@metrico.lu> To: freebsd-geom@freebsd.org Subject: Geom stripe bottleneck Message-ID: <538D9BC3.6040509@metrico.lu>
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Hi all, I have a stripe (RAID0) geom setup for my database's data. Currently I am applying some large updates on the data and I think the performance of my stripe could be better. But I am uncertain and so I thought I'd request some interpretation help from the community :) The stripe consists of two disks (WD Velociraptor with 10.000 rpm): >diskinfo -v ada2 ada2 512 # sectorsize 600127266816 # mediasize in bytes (558G) 1172123568 # mediasize in sectors 0 # stripesize 0 # stripeoffset 1162821 # Cylinders according to firmware. 16 # Heads according to firmware. 63 # Sectors according to firmware. WD-WXH1E61ASNX9 # Disk ident. and /var/log/dmesg.boot # snip ada2 at ahcich2 bus 0 scbus2 target 0 lun 0 ada2: <WDC WD6000HLHX-01JJPV0 04.05G04> ATA-8 SATA 3.x device ada2: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes) ada2: Command Queueing enabled ada2: 572325MB (1172123568 512 byte sectors: 16H 63S/T 16383C) ada2: Previously was known as ad8 ada3 at ahcich3 bus 0 scbus3 target 0 lun 0 ada3: <WDC WD6000HLHX-01JJPV0 04.05G04> ATA-8 SATA 3.x device ada3: 300.000MB/s transfers (SATA 2.x, UDMA6, PIO 8192bytes) ada3: Command Queueing enabled ada3: 572325MB (1172123568 512 byte sectors: 16H 63S/T 16383C) ada3: Previously was known as ad10 #snap And here's some iostat -d -w 10 ada0 ada1 ada2 ada3 example output #snip ada0 ada1 ada2 ada3 KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s KB/t tps MB/s 0.00 0 0.00 0.00 0 0.00 19.33 176 3.32 19.33 176 3.32 16.25 0 0.01 16.25 0 0.01 16.87 133 2.20 16.87 133 2.20 0.00 0 0.00 0.00 0 0.00 16.77 146 2.40 16.77 147 2.40 0.00 0 0.00 0.00 0 0.00 19.46 170 3.24 19.45 170 3.23 21.50 0 0.01 21.50 0 0.01 17.00 125 2.08 17.00 125 2.08 0.50 0 0.00 0.50 0 0.00 16.88 145 2.38 16.88 145 2.38 0.00 0 0.00 0.00 0 0.00 16.96 125 2.07 16.97 125 2.07 0.00 0 0.00 0.00 0 0.00 19.82 158 3.06 19.81 158 3.07 28.77 1 0.03 28.77 1 0.03 16.83 133 2.19 16.82 133 2.19 #snap I think the MB/s output is rather low for such a disk. To gain further insight I started gstat: dT: 1.001s w: 1.000s L(q) ops/s r/s kBps ms/r w/s kBps ms/w %busy Name 0 27 0 0 0.0 27 2226 4.8 7.0| ada0 0 28 1 32 23.9 27 2226 1.3 3.9| ada1 2 120 115 1838 6.4 5 96 0.2 74.3| ada2 2 121 116 1854 6.3 5 96 0.4 72.9| ada3 0 28 1 32 24.0 27 2226 5.0 8.7| mirror/gm 2 121 116 3708 7.9 5 192 0.4 92.2| stripe/gs 0 28 1 32 24.0 27 2226 5.0 8.7| mirror/gms1 0 12 0 0 0.0 12 1343 9.1 6.9| mirror/gms1a 0 0 0 0 0.0 0 0 0.0 0.0| mirror/gms1b 0 0 0 0 0.0 0 0 0.0 0.0| mirror/gms1d 0 0 0 0 0.0 0 0 0.0 0.0| mirror/gms1e 0 16 1 32 24.0 15 883 1.7 2.9| mirror/gms1f What bothers me here is that the stripe/gs is 92% busy while the disks themselves are only at 74/72%. This lead me to my post here and seek some advice, since I don't know enough about the mechanics and so I can't really find the problem, if there is any at all. Btw, here's the output from geom stripe list: # geom stripe list Geom name: gs State: UP Status: Total=2, Online=2 Type: AUTOMATIC Stripesize: 8192 ID: 1042782665 Providers: 1. Name: stripe/gs Mediasize: 1200254517248 (1.1T) Sectorsize: 512 Stripesize: 8192 Stripeoffset: 0 Mode: r1w1e1 Consumers: 1. Name: ada2 Mediasize: 600127266816 (558G) Sectorsize: 512 Mode: r1w1e2 Number: 0 2. Name: ada3 Mediasize: 600127266816 (558G) Sectorsize: 512 Mode: r1w1e2 Number: 1 So is there some bottleneck or I am just worrying about nothing? Many thanks, Frank -- Frank BRONIEWSKI METRICO s.à r.l. géomètres technologies d'information géographique rue des Romains 36 L-5433 NIEDERDONVEN tél.: +352 26 74 94 - 28 fax.: +352 26 74 94 99 http://www.metrico.lu
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