IIS 5 & IIS 6
sc-bytes=0 static image files from UNC share
Last post Dec 10, 2007 08:53 PM by acston
Nov 23, 2007 11:46 AM|jhamoline|LINK
I have 2 servers running IIS 6 serving static file content (images) off of a NAS device and users have been reporting that some images do not appear once in a while, randomly.
When looking through the IIS logs I didn't find any 400's or 500's to explain this problem so I dug a bit deeper and found that IIS is responding with a 200 status but not sending any data, sc-bytes=0. The backend is a NetApp 3020 filer with a CIFS share
which IIS connects to via a vdir. Here is a snippet from a logparser query.
The query is: logparser -q:ON "SELECT count(cs-uri-stem) AS occurences, cs-uri-stem FROM C:\WINDOWS\system32\LogFiles\W3SVC82852001\ex071122.log WHERE sc-bytes=0 GROUP BY cs-uri-stem ORDER BY occurences DESC"
1212 /p2a/listing/8521/2ef7/53c1/f1bab76a72dc6cdbb692/w475h356.jpg1208 /p2a/listing/c3e9/50ab/a9d7/27db0e0925c7c1ddf84e/w475h356.jpg1207 /p2a/listing/9e14/9d3b/aff5/30d4e01f896b509e208b/w475h356.jpg1204 /p2a/listing/6665/fdac/9a4d/2982171b2548dec1750c/w475h356.jpg1197 /p2a/listing/e656/d6dc/a359/8e4b2b7cb5b685b3d67f/w475h356.jpg1195 /p2a/listing/5058/97c5/922b/eaceba324bf49e2c188d/w475h356.jpg1194 /p2a/listing/c90b/80a9/5f94/c5f983e45f16f8152420/w475h356.jpg1193 /p2a/listing/a6f2/7634/6bb7/a9e9fd350b62273acb0b/w475h356.jpg1184 /p2a/listing/d0ad/c87f/460b/c774eeb6421b3c8b7336/w475h356.jpg1183 /p2a/listing/6926/a756/bdd7/03bd2c612e17ce8a5723/w475h356.jpg307 /p2a/listing/9f7d/e3c9/0786/5e7f4993881969a2f9d5/original.jpg
Can someone help me trooublshoot this issue, or give me some pointers beyond the generic information MS provides for UNC shares? I've tried all the registry hacks I can find and none of them have helped.
Services\LanmanWorkstation\Parameters\MaxCmds = 16384
Services\InetInfo\Parameters\ActivityPeriod = 6000
Services\InetInfo\Parameters\MemCacheSize = 1024
Services\HTTP\Parameters\UriMaxBytes = 262144
Services\HTTP\Parameters\UriScavengerPeriod = 30
Nov 25, 2007 02:22 PMemail@example.com|LINK
Check the NAS permissions for the account accessing the images. I believe your NAS runs a Linux, not Windows, so it won't respond with the sane errors.
Nov 26, 2007 09:53 AM|jhamoline|LINK
Permissions are fine. The images are served one second and not the next which makes me think it might be load on the fileserver, would you expect IIS to respond that way if the fileserver is not responding correctly or if it was responding slowly?
Dec 10, 2007 08:53 PM|acston|LINK
We are seeing this same problem on a static content server. We see 90+% of our static content with sc-bytes=0. Our scenario is not using a NAS. One possibility we're investigating is http.sys configuration settings affecting the log files. We have not
seen any direct evidence that this is causing a problem. But we're out of other obvious ideas.