Messages in this thread | | | Subject | RE: Ext3 vs NTFS performance | Date | Fri, 4 May 2007 12:52:30 -0700 | From | "Cabot, Mason B" <> |
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> > Cabot, Mason B wrote: > > I've been testing the NAS performance of ext3/Openfiler 2.2 against > > NTFS/WinXP and have found that NTFS significantly > outperforms ext3 for > > video workloads. The Windows CIFS client will attempt a poor-man's > > pre-allocation of the file on the server by sending 1-byte writes at > > 128K-byte strides, breaking block allocation on ext3 and leading to > > fragmentation and poor performance. This will happen for many > > applications (including iTunes) as the CIFS client issues these > > pre-allocates under the application layer. > > This is rather hard to believe so I think some more information is in > order. Specifically, how do you know that it is the windows > kernel that > is issuing these writes and not the application? Under what > application > access patterns does it do this? > > This is just rather hard to believe seeing as how, iirc, the CIFS > protocol has commands to extend the file size properly rather > than with > this hack, and unless it is asked to by the application, the > cifs client > should not be trying to extend files. >
Philip:
the best response I can offer is that we have traced the application's file system accesses and seen no such one-byte writes occuring at that level. They are generated somewhere below the application. Additionally, while we have observed iTunes on Windows issuing these one-byte writes, ethereal traces for iTunes on Mac OSX show no such behavior. Because of these observations I think it is reasonable to conclude that the Windows CIFS client is generating the one-byte writes.
thanks, Mason
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