Date: Sat, 20 Feb 99 18:12:14 -0800 From: Dennis Glatting <dennis.glatting@software-munitions.com> To: "Kenneth D. Merry" <ken@plutotech.com> Cc: freebsd-current@FreeBSD.ORG Subject: Re: Slow seq. write on Seagate ST36530N Message-ID: <199902210212.SAA07089@imo.plaintalk.bellevue.wa.us> References: <199902210029.RAA15447@panzer.plutotech.com>
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> > Just to throw my voice in, I get crappy SCSI performance on my > > three SCSI card Dell. I don't understand why. > > Umm, you're going to have to be a little more specific than that. > > You do have one of those slow Western Digital drives, which > could cause some problems. > The WD drive is on its own controller. The ST410800W is on its own controller. The two ST43400Ns are together on the third controller. On the ST410800W I am getting, according to iozone: > btw# iozone 1024 8192 /ExternalDisk/junk > .... > Writing the 1024 Megabyte file, '/ExternalDisk/junk'...299.609375 seconds > Reading the file...178.609375 seconds > > IOZONE performance measurements: > 3583805 bytes/second for writing the file > 6011676 bytes/second for reading the file > Since this is a 16 bit device with 10 MHz transfer rate I expect better, or should I not? According to the disk specs the average internal transfer rate is 7.2 MB/sec, 20 MB/sec external burst. The following is an examination of the device's mode pages. I'm currently looking at each variable and their meaning, though I am not a SCSI guru. > ==> 0 > > 00 00 00 00 00 00 00 00 > 00 00 00 00 00 00 00 > > > > > ==> 1 > > AWRE (Auto Write Reallocation Enbld): 1 > ARRE (Auto Read Reallocation Enbld): 0 > TB (Transfer Block): 0 > RC (Read Continuous): 0 > EER (Enable Early Recovery): 1 > PER (Post Error): 0 > DTE (Disable Transfer on Error): 0 > DCR (Disable Correction): 0 > Read Retry Count: 27 > Correction Span: 48 > Head Offset Count: 0 > Data Strobe Offset Count: 0 > Write Retry Count: 1 > Recovery Time Limit: 65535 > > > > > ==> 2 > > Buffer Full Ratio: 44 > Buffer Empty Ratio: 238 > Bus Inactivity Limit: 10 > Disconnect Time Limit: 0 > Connect Time Limit: 0 > Maximum Burst Size: 0 > DTDC: 0 > > > > > ==> 3 > > Tracks per Zone: 27 > Alternate Sectors per Zone: 9 > Alternate Tracks per Zone: 0 > Alternate Tracks per Logical Unit: 27 > Sectors per Track: 133 > Data Bytes per Physical Sector: 512 > Interleave: 1 > Track Skew Factor: 10 > Cylinder Skew Factor: 21 > SSEC: 0 > HSEC: 1 > RMB: 0 > SURF: 0 > > > > > ==> 4 > > Number of Cylinders: 4926 > Number of Heads: 27 > Starting Cylinder-Write Precompensation: 0 > Starting Cylinder-Reduced Write Current: 0 > Drive Step Rate: 0 > Landing Zone Cylinder: 0 > RPL: 0 > Rotational Offset: 0 > Medium Rotation Rate: 5400 > > > > > ==> 7 > > EER: 0 > PER: 1 > DTE: 0 > DCR: 0 > Verify Retry Count: 27 > Verify Correction Span: 48 > Verify Recovery Time Limit: 65535 > > > > > ==> 8 > > IC: 0 > ABPF: 0 > CAP: 1 > DISC: 1 > SIZE: 0 > WCE: 1 > MF: 0 > RCD: 0 > Demand Retention Priority: 0 > Write Retention Priority: 0 > Disable Pre-fetch Transfer Length: 65535 > Minimum Pre-fetch: 0 > Maximum Pre-fetch: 29 > Maximum Pre-fetch Ceiling: 477 > > > > > ==> 10 > > RLEC: 0 > Queue Algorithm Modifier: 1 > QErr: 0 > DQue: 0 > EECA: 0 > RAENP: 0 > UAAENP: 0 > EAENP: 0 > Ready AEN Holdoff Period: 0 > > > > > ==> 12 > > 80 00 00 16 00 00 00 00 > 00 00 00 13 3d 1a 00 00 > 00 00 00 00 10 00 00 00 > 00 00 00 00 00 00 00 00 > 00 00 00 > > To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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