I have multiple rclone sync tasks with their own unique filters that do not overlap. Only one instance of each task can run at a time so that I can limit the number of transfers occurring simultaneously. I also don't know how well rclone deals with 2 syncs attempting to upload the same file. The oldest files are transferred first.
The problem that I am running into is that a task may have one large file uploading out of a 3 transfer limit. The final large transfer blocks the syncing of newer files that did not exist when the task started.
Is there a built-in option to have rclone re-check for files that match the filter when it has begun transferring the final files from previous check, or a standard way to handle this scenario while 1) being able to control number of transfers, and 2) not running into problems with overlapping upload attempts?
Related
I am trying to find a way to make rsyslog write logs into multiple files simultaneous, that is received from the same host. For example write to two files, and switch every log line.
I have one host that sends insane amounts of data (600gb a day), and i want write this logs to multiple files instead of one.
This is because of Splunk that read this file for indexing purposes, cant utilize multiple pipelines (aka. multiple CPU threads) on the same file, and this causes an bottleneck.
I was thinking about making rsyslog writing a new file every second, but this does not sound optimal.
Any suggestion is much appreciated :)
I have not been able to find any documentation that describes this ability in rsyslog.
The solution for this is to use part of the subseconds to split the file randomly (using last 2 digits, nano seconds) to 100 files at the same time.
template(name="template_nano_file_format" type="list") {
property(name="$.path")
property(name="fromhost-ip")
constant(value="/")
property(name="$year")
property(name="$month")
property(name="$day")
constant(value="-")
property(name="$hour")
constant(value="-")
property(name="timegenerated" dateFormat="subseconds" regex.expression="..$" regex.type="ERE")
constant(value=".log")
}
Let’s pretend I have a network of 10,000 machines. I want to use all those machines to crawl the web as fast as possible. All pages should be downloaded only once. In addition there must be no single point of failure and we must minimize the number of communication required between machines. How would you accomplish this?
Is there anything more efficient than using consistent hashing to distribute the load across all machines and minimize communication between them?
Use a distributed Map Reduction system like Hadoop to divide the workspace.
If you want to be clever, or doing this in an academic context then try a Nonlinear dimension reduction.
Simplest implementation would probably be to use a hashing function on the name space key e.g. the domain name or URL. Use a Chord to assign each machine a subset of the hash values to process.
One Idea would be to use work queues (directories or DB), assuming you will be working out storage such that it meets your criteria for redundancy.
\retrieve
\retrieve\server1
\retrieve\server...
\retrieve\server10000
\in-process
\complete
1.) All pages to be seeds will be hashed and be placed in the queue using the hash as a file root.
2.) Before putting in the queue you check the complete and in-process queues to make sure you don't re-queue
3.) Each server retrieves a random batch (1-N) files from the retrieve queue and attempts to move it to the private queue
4.) Files that fail the rename process are assumed to have been “claimed” by another process
5.) Files that can be moved are to be processed put a marker in in-process directory to prevent re-queuing.
6.) Download the file and place it into the \Complete queue
7.) Clean file out of the in-process and server directories
8.) Every 1,000 runs check the oldest 10 in-process files by trying to move them from their server queues back into the general retrieve queue. This will help if a server hangs and also should load balance slow servers.
For the Retrieve, in-process and complete servers most file systems hate millions of files in 1 directory, Divide storage into segments based on the characters of the hash \abc\def\123\ would be the directory for file abcdef123FFFFFF…. If you were scaling to billions of downloads.
If you are using a mongo DB instead of a regular file store much of these problems would be avoided and you could benefit from the sharding etc…
In our appliation,we save some images in different folders like:
1
2
3
4
...
500
...
And inside each folder there are large amount of images whose size is (5kb-20kb).
Now we found that when we try to transfer these files,we have to compress them first using the winrar,however it cost toooooo much time!! Also two hours to compress one parent folder.
In fact the images in the application are map images like the google map tiles:
||
So I wonder if there is an good idea to save/transfer these small but large amount files?
Images like that are likely to already be compressed so you will get little gain in bandwidth use (and so transfer speed) from the compression step.
If the compression process is taking along time where your CPU is busy then try instead just creating a plain tar file (which joins all the files into one archive without applying any compression). I don't know about winrar but most other compression tools (like 7zip) can generate a tar file, so I'm guessing winrar can too.
If you regularly transfer the whole set of files but only small numbers are added/changed each time, you might want to look into other transfer methods like rsync. You don't describe either of your environments so I can't tell if this is likely to be available to you, but if it is rsync does an excellent job of only transferring changes (speeding up the transfer significantly) and it also always uses one connection so you don't get hit by the per file latency of FTP and other protocols - one file follows the previous one down the same connection as if the parts being transferred had been tared together so you don't need that extra step to pack the files at one and (and unpack them at the other).
Those images are already compressed. However, to increase transfer speed, you might try using rar in 'archive' mode. This does the same thing as tar: concatenates all the files together into one big file. Don't use any compression in your archive format.
Maybe you can use a fast compression library like Snappy. However, it can only compress a single file, and you surely don't want to transfer each file separately. I'd create an uncompressed TAR archive for that.
So, I am in this little predicament where I am stuck watching a few ftp folders to see if they have new files added to them. If they do, it needs to throw an event with the file name. Thereby telling something else to download that file.
This is a pretty simple object to make, I was just curious if anyone knew how expensive this operation would be?
I plan on using the command NLIST because I don't need file size information, and there will be no sub-directories in the folder. Each file in the folder will have exactly 25 characters in its name.
There could be anywhere from 10 to 'maybe' a couple thousand (max around 2000) files per folder (usually on the lower end, 100-300, but currently growing).
The files are anywhere from 250kb to a very VERY unlikely 10mb (usually within the 250kb to 4mb range).
There possibly could be up to a few hundred folders (in which case I could change the watch frequency depending on number of folders), but currently there are only a few (6-10ish).
There also would be multiple logins for the ftp server, different logins would have access to different folders.
I am not asking for an implementation, just if anyone has some first or second hand knowledge about FTP, how could this affect my network.
I am not opposed to putting in file retention times or change the frequency in which I check for new files.
Do you have any control over the remote servers? FTP isn't really optimized for this, and you could probably do a lot better with some sort of dedicated mini-server. You could use file system monitoring on the remote side and just send out the filenames when they arrive rather than continuously polling. You'd only need to have one connection open too, rather than the two that FTP requires.
I have an app that I'm writing that takes files in a specific directory that have been uploaded via SFTP and moves them to S3.
I have a problem where my cron job starts uploading a file when it's not completely uploaded. I have thought of every way to try and wait until the file is complete, but I have no way of knowing (that I know of).
I'm hoping that the collective genius of SO would be able to shed some light on this!
There are a number of ways to handle this:
Change the upload process to upload the data file itself (e.g., data.txt) followed by a sentinel file (e.g., data.txt.sentinel). Then wait for the sentinel before processing the data file and deleting them both. Data files older then N days with no corresponding sentinel - just delete them. This is only good if you can change the uploader.
If you can evaluate the content of the file to check completeness, this is another way. For example, if you're only uploading HTML files, you could check that it ends with </html>. Not always possible unless you can control what's being uploaded.
The not-been-modified-for-a-while method. Basically, if the file hasn't been modified for N minutes, you can assume the upload has been finished. This may still result in the processing of incomplete files where the transfer has failed partway through.
All these methods have their advantages and drawbacks and you will have to decide which is the best for you. We try to opt for number 1 where we can influence the uploading side.
And remember that N is configurable in the above scenarios. You need to balance the possibility that a too-small N will result in you processing an incomplete file in option 3 but too large a value of N will delay the processing of said file.
Is there any way you can add a step after the SFTP transfer? The idea is to SFTP the files to a temporary directory, then once that's done have the same client execute (via SSH) a script to mv the files over to the directory the cron job is looking at. mv is atomic on many local Unix filesystems, so the cron job will only either see the old file or the new one.
Of course, if you can execute a script after the SFTP transfer you can just have the script do the transfer to S3, without the cron job ;)
We are using pure-ftpd for a very similar process. Rather then having a cron job do the uploads, we use the upload script option of pure-ftp, which triggers a script every time an upload is complete. You might consider using a similar mechanism if it is available with your ftp server.