I'm not sure this is related, but if you do a nfsstat -m on the client, does it show the rsize to be 8192 or 32768? When reading data from our NetApps using our E450's we don't see anywhere near the same performance as when we read data from our E450's with our E450's using NFS3 over udp. I've always attributed this to the client code forcing an rsize of 8192 when connecting to the filler, and allowing a rsize of 32768 when connecting to anything else (Sun, Dec, SGI). Has anyone else seen this?
The difference grew even more noticeable when we moved the traffic from a dedicated 100 Mb FX crossover to a 1000 Mb FX switched environment. Prior to switch, numbers like yours for Sun from NetApps reads, ~11 MB/Sec sun from Sun reads, after the switch Sun from NetApp ~18MB/sec, Sun from Sun ~50 MB/sec.
The NetApp server is a 740 with 6 shelves, and the Sun's are E450's 4/400 MHz with an A5200 array, 1+0 configuration.
-----Original Message----- From: Val Bercovici (NetApp) [mailto:valb@netapp.com] Sent: Thursday, April 01, 1999 9:41 AM To: Brian Tao Cc: toasters@mathworks.com; sirbruce@ix.netcom.com Subject: RE: Slow sequential disk reads on F740
What sort of guidelines do people follow when deciding on theminra setting? At one end of the spectrum, you have broadcast video streaming servers that deal exclusively with long, sequential reads. At the other end, you have something like an INN server storing articles in individual files. Are there any tools to help decide which setting is best, or do you just "eyeball" it and try both settings and see which one seems better?
My simple rule is minra=on for crazy apps like INN what have tons of small totally random I/O's and minra=off for almost anything else. Basically, if you think caching will help you in any way you want minra off.
A single drive should be able to sustain 8MB/sec or higher just onits own... a stripe of five drives should hit at least 40MB/sec. sysstat on that filer does in fact report 38 to 43MB/sec disk reads during a "vol scrub".
Actually, the 9GB SCSI drives I believe you're using are only rated for a max (not sustained) external transfer rate of 5MB/sec, so the numbers you're seeing really make sense to me. FYI, the max external transfer (not sustained) rate for our 18GB FC-AL drives is a much nicer 12.5MB/sec so you would probably see better (although not necessarily double <g>) sequential performance with those....
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