From 2c70cd4f3e3b40bcf2fb80dc8751adfebb2bae77 Mon Sep 17 00:00:00 2001 From: zooko <> Date: Tue, 10 Jun 2008 23:32:12 +0000 Subject: [PATCH] replace with link to docs/known_issues.txt (for now) [Imported from Trac: page KnownIssues, version 4] --- KnownIssues.md | 154 +------------------------------------------------ 1 file changed, 1 insertion(+), 153 deletions(-) diff --git a/KnownIssues.md b/KnownIssues.md index 09d27fc..25ef13d 100644 --- a/KnownIssues.md +++ b/KnownIssues.md @@ -1,153 +1 @@ -# Known Issues - -Below is a list of known issues in recent releases of Tahoe, and how to manage -them. - - -## issues in Tahoe v1.1.0, released 2008-06-10 - -### issue 1: server out of space when writing mutable file - -If a v1.0 or v1.1.0 storage server runs out of disk space then its attempts to -write data to the local filesystem will fail. For immutable files, this will -not lead to any problem (the attempt to upload that share to that server will -fail, the partially uploaded share will be deleted from the storage server's -"incoming shares" directory, and the client will move on to using another -storage server instead). - -If the write was an attempt to modify an existing mutable file, however, a -problem will result: when the attempt to write the new share fails due to -insufficient disk space, then it will be aborted and the old share will be left -in place. If enough such old shares are left, then a subsequent read may get -those old shares and see the file in its earlier state, which is a "rollback" -failure. With the default parameters (3-of-10), six old shares will be enough -to potentially lead to a rollback failure. - -#### how to manage it - -Make sure your Tahoe storage servers don't run out of disk space. This means -refusing storage requests before the disk fills up. There are a couple of ways -to do that with v1.1. - -First, there is a configuration option named "sizelimit" which will cause the -storage server to do a "du" style recursive examination of its directories at -startup, and then if the sum of the size of files found therein is greater than -the "sizelimit" number, it will reject requests by clients to write new -immutable shares. - -However, that can take a long time (something on the order of a minute of -examination of the filesystem for each 10 GB of data stored in the Tahoe -server), and the Tahoe server will be unavailable to clients during that time. - -Another option is to set the "readonly_storage" configuration option on the -storage server before startup. This will cause the storage server to reject -all requests to upload new immutable shares. - -Note that neither of these configurations affect mutable shares: even if -sizelimit is configured and the storage server currently has greater space used -than allowed, or even if readonly_storage is configured, servers will continue -to accept new mutable shares and will continue to accept requests to overwrite -existing mutable shares. - -Mutable files are typically used only for directories, and are usually much -smaller than immutable files, so if you use one of these configurations to stop -the influx of immutable files while there is still sufficient disk space to -receive an influx of (much smaller) mutable files, you may be able to avoid the -potential for "rollback" failure. - -A future version of Tahoe will include a fix for this issue. Here is -[the mailing list -discussion](http://allmydata.org/pipermail/tahoe-dev/2008-May/000630.html) about how that future version will work. - - -## issues in Tahoe v1.1.0 and v1.0.0 - -### issue 2: pyOpenSSL and/or Twisted defect resulting false alarms in the unit tests - -The combination of Twisted v8.1.0 and pyOpenSSL v0.7 causes the Tahoe v1.1 unit -tests to fail, even though the behavior of Tahoe itself which is being tested is -correct. - -#### how to manage it - -If you are using Twisted v8.1.0 and pyOpenSSL v0.7, then please ignore XYZ in -XYZ. Downgrading to an older version of Twisted or pyOpenSSL will cause those -false alarms to stop happening. - - -## issues in Tahoe v1.0.0, released 2008-03-25 - -(Tahoe v1.0 was superceded by v1.1 which was released 2008-06-10.) - -### issue 3: server out of space when writing mutable file - -In addition to the problems caused by insufficient disk space described above, -v1.0 clients which are writing mutable files when the servers fail to write to -their filesystem are likely to think the write succeeded, when it in fact -failed. This can cause data loss. - -#### how to manage it - -Upgrade client to v1.1, or make sure that servers are always able to write to -their local filesystem (including that there is space available) as described in -"issue 1" above. - - -### issue 4: server out of space when writing immutable file - -Tahoe v1.0 clients are using v1.0 servers which are unable to write to their -filesystem during an immutable upload will correctly detect the first failure, -but if they retry the upload without restarting the client, or if another client -attempts to upload the same file, the second upload may appear to succeed when -it hasn't, which can lead to data loss. - -#### how to manage it - -Upgrading either or both of the client and the server to v1.1 will fix this -issue. Also it can be avoided by ensuring that the servers are always able to -write to their local filesystem (including that there is space available) as -described in "issue 1" above. - - -### issue 5: large directories or mutable files in a specific range of sizes - -If a client attempts to upload a large mutable file with a size greater than -about 3,139,000 and less than or equal to 3,500,000 bytes then it will fail but -appear to succeed, which can lead to data loss. - -(Mutable files larger than 3,500,000 are refused outright). The symptom of the -failure is very high memory usage (3 GB of memory) and 100% CPU for about 5 -minutes, before it appears to succeed, although it hasn't. - -Directories are stored in mutable files, and a directory of approximately 9000 -entries may fall into this range of mutable file sizes (depending on the size of -the filenames or other metadata associated with the entries). - -#### how to manage it - -This was fixed in v1.1, under ticket #379. If the client is upgraded to v1.1, -then it will fail cleanly instead of falsely appearing to succeed when it tries -to write a file whose size is in this range. If the server is also upgraded to -v1.1, then writes of mutable files whose size is in this range will succeed. -(If the server is upgraded to v1.1 but the client is still v1.0 then the client -will still suffer this failure.) - - -### issue 6: pycryptopp defect resulting in data corruption - -Versions of pycryptopp earlier than pycryptopp-0.5.0 had a defect which, when -compiled with some compilers, would cause AES-256 encryption and decryption to -be computed incorrectly. This could cause data corruption. Tahoe v1.0 -required, and came with a bundled copy of, pycryptopp v0.3. - -#### how to manage it - -You can detect whether pycryptopp-0.3 has this failure when it is compiled by -your compiler. Run the unit tests that come with pycryptopp-0.3: unpack the -"pycryptopp-0.3.tar" file that comes in the Tahoe v1.0 `misc/dependencies` -directory, cd into the resulting `pycryptopp-0.3.0` directory, and execute -`python ./setup.py test`. If the tests pass, then your compiler does not -trigger this failure. - -Tahoe v1.1 requires, and comes with a bundled copy of, pycryptopp v0.5.1, which -does not have this defect. +Please see source:docs/known_issues.txt. \ No newline at end of file