Re: [Samba] File corruption with write cache enabled - patch included
> On Thu, Oct 03, 2002 at 12:52:10PM +0200, Rasmus Borup Hansen wrote: > > I recently found out that write caching in samba sometimes leads to > > file corruption (the setup program for Sophos Antivirus generates > > corrupted files when making a "central installation" on a Samba > > share). > > > > This morning I tracked down the place in the Samba code that leads to > > corruption. Here is what happened to me: > > > > "write cache size" is 8192 bytes. A client opens a new file and writes > > byte no. 30959. This byte is cached. Then the program write byte > > no. 61919 which is written directly to the disk, since the cache > > doesn't go that far. The client then writes bytes no. 0 through > > 61920. Since these bytes don't fit into the cache they are written > > directly to the disk. However, the cached byte at position 30959 is > > not discarded. When this byte is later written to the disk, the file > > will get corrupted. > > > > The patch below detects this situation and discards the cached > > byte(s). I guess that some profiling code should also be added at some > > time. The patch is against version 2.2.5. > > > > Perhaps you should warn users of current versions against using write > > caching. > > > > I believe that this bug is the same as bug no. 24502 submitted by > > Henrik Qwinto <[EMAIL PROTECTED]>. > > > > Best regards, and thank you for making Samba, > > Damn good call ! Very good bugfix. I've committed it to all > Samba branches. Thanks a *lot* for this fix ! > > Jeremy. > -- Is this patch included in 2.2.6. > >Perhaps you should warn users of current versions against using write > > caching. Are we talking about oplocked files or has it also something to do with "strict sync". Bo. -- To unsubscribe from this list go to the following URL and read the instructions: http://lists.samba.org/mailman/listinfo/samba
[Samba] How is the Samba people stress testing Samba.
Over the years I have seen a number of strange integrity problems when using Samba servers, and I sometime wonder how Samba is stress tested. As long as a Samba server is used as a normal file server, we very seldom se any problems, but if heavily used, flat file databases are used, some versions of Samba are more stable then others. Even with oplocks disabled and strict locking enabled, we could not always stop the corruption of files. A number of years ago I wrote a DOS program designed to run on multiple client hosts, stress and integrity testing a shared file on a Windows NT 3.51 file servers. In principal the program continuously locks a random part of the testfile (on the server), reads the data and test the data for errors, then writes a new testpattern and removes the lock. Lately I have tried it on different Samba servers with very different results. When I tried to test a Samba 2.2.5 server (SuSE 8.0 Kernel 2.4.19, oplocks disabled, AMD XP1900+, 256MB) with two Win98 clients, the clients could never run more then maybe 6 hours before one of the clients completely lost contact with the Samba server and had to be rebooted. Two bytes in the 250MB testfile was corrupted. If only one client was run, the client still lost contact to the server and had to be rebooted. When the same test was run on a Samba 2.2.6 server (SuSE 8.1 Kernel 2.4.19, oplocks disabled, AMD XP1900+, 256MB, and the same Win98 clients), the clients never lost contact to the server, but I have not yet been able to run the test more the maybe 48 hours without a corruption of the testfile. The reason I'm looking into this problem is that I have 3 users (clients here are two W2K, and one Win98) that run an old DOS shared flatfile database that we have moved from a Win98 machine to Linux, and it has really been a nightmare. First we moved it to the Samba 2.2.5 server, but it did not take more then a couple of hours before the database was corrupted. Then we moved to the 2.2.6 server and things started to look a lot better, but the corruption did not stop, it just took maybe one or two days before we saw corruption. The application has run for more the 4 years on the Win98 machine, and data has never been corrupted. I'm not yet sure, but errors happens even if only one user using the database. I think the database is based on Paradox. I'm thinking of reviewing my old DOS program (if I can find the source code) and see what happens if it's recompiled with a new compiler. I Think the program was compiled with Borland C 3.0. Any suggestions (besides moving back to Win98). Thanks in advanceBo Jacobsen
Re: [Samba] How is the Samba people stress testing Samba.
> Bo:> > I'm in the "testing and proof" stage of converting from Windows NT 4 to> Linux/SAMBA and I'm very interested in any "stress testing" that you (or> anyone else) could point me to. If you get your DOS Program working,> would you mind sharing it?> > The other thing that interests me in your post is the corruption of a> Paradox database. I'm also trying to convert of a buddy of mine to the> SAMBA scene at his wife's Veterinarian clinic. They use a Paradox> database for just about ALL of their record keeping and billing. Last> week we setup a test server with Red Hat 8 and Samba 2.2.5 and got nearly> 4 times the performance over Windows 2000 running the database on the same> hardware. The problem is that they *pound* on the database 8-12 hours a> day 6 days a week. I I'm looking at corruption 4-48 into production, I'm> not going to have a buddy for very long Have been able to learn> anything more on this front?> > I'm going back out the clinic tonight to do some more testing and I'll> report anything that happens while I'm there.> > Kevin> > I understand your worry. I'm right now considering going back to Win98 as we have to figure out, where exactly the problem lies. I have tried with different kernels 2.4.16 through 2.4.19 but have not yet been able to solve this issue. If I were you I would be very careful about moving the database as things are right now. I suggest that you at least run a very lengthy concurrent paradox stress test (from multiply workstations) before moving. You could have a copy of my DOS testprogram, but it's in Danish and I have never translated it to English. The program was written as we had problems with database corruption when moving a financial database from Netware to Windows NT3.5. The reason I posted the original message is that I'm really interested in knowing how Samba has been stress tested. Bo
Fw: [Samba] How is the Samba people stress testing Samba.
> > I'm in the "testing and proof" stage of converting from Windows NT 4 to> Linux/SAMBA and I'm very interested in any "stress testing" that you (or> anyone else) could point me to. If you get your DOS Program working,> would you mind sharing it?> > The other thing that interests me in your post is the corruption of a> Paradox database. I'm also trying to convert of a buddy of mine to the> SAMBA scene at his wife's Veterinarian clinic. They use a Paradox> database for just about ALL of their record keeping and billing. Last> week we setup a test server with Red Hat 8 and Samba 2.2.5 and got nearly> 4 times the performance over Windows 2000 running the database on the same> hardware. The problem is that they *pound* on the database 8-12 hours a> day 6 days a week. I I'm looking at corruption 4-48 into production, I'm> not going to have a buddy for very long Have been able to learn> anything more on this front?> > I'm going back out the clinic tonight to do some more testing and I'll> report anything that happens while I'm there.> > Kevin> > I understand your worry. I'm right now considering going back to Win98 as we have to figure out, where exactly the problem lies. I have tried with different kernels 2.4.16 through 2.4.19 but have not yet been able to solve this issue. If I were you I would be very careful about moving the database as things are right now. I suggest that you at least run a very lengthy concurrent paradox stress test (from multiply workstations) before moving. You could have a copy of my DOS testprogram, but it's in Danish and I have never translated it to English. The program was written as we had problems with database corruption when moving a financial database from Netware to Windows NT3.5. The reason I posted the original message is that I'm really interested in knowing how Samba has been stress tested. Bo
[Samba] Where is the WINS info saved.
Is Samba using a file where it saves WINS info on machines. At times it could be useful to see what machine info Samba has gathered. Than in Advance Bo Jacobsen
[Samba] My W2k client generates internal errors / panic in samba ?
socket options = SO_KEEPALIVE IPTOS_LOWDELAY TCP_NODELAY
veto files = /*.eml/*.nws/riched20.dll/*.{*}/
character set = ISO8859-15
client code page = 850
# strict locking = yes
oplocks = false
logon script = brugere.bat
wins support = yes
----
Any idears
Thanks in advance
Bo Jacobsen
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