X-Git-Url: https://pere.pagekite.me/gitweb/homepage.git/blobdiff_plain/e1e1e0bd163714f4e39c5d0c7bdeb282d61b6de3..d3a7ce86b16da092e58f0cb614bdd6fc6be5513c:/blog/index.html diff --git a/blog/index.html b/blog/index.html index 50cf807a1d..d2e9ca02f0 100644 --- a/blog/index.html +++ b/blog/index.html @@ -19,6 +19,174 @@ +
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Lenker for 2014-08-03
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3rd August 2014
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Lenge siden jeg har hatt tid til å publisere lenker til skriverier +jeg har hatt glede og nytte av av å lese. Her er en liten norsk +lenkesamling.

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+ + + Tags: lenker, norsk, opphavsrett, personvern. + + +
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Debian Edu interview: Bernd Zeitzen
31st July 2014
@@ -712,294 +880,6 @@ jobb.

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S3QL, a locally mounted cloud file system - nice free software
-
9th April 2014
-

For a while now, I have been looking for a sensible offsite backup -solution for use at home. My requirements are simple, it must be -cheap and locally encrypted (in other words, I keep the encryption -keys, the storage provider do not have access to my private files). -One idea me and my friends had many years ago, before the cloud -storage providers showed up, was to use Google mail as storage, -writing a Linux block device storing blocks as emails in the mail -service provided by Google, and thus get heaps of free space. On top -of this one can add encryption, RAID and volume management to have -lots of (fairly slow, I admit that) cheap and encrypted storage. But -I never found time to implement such system. But the last few weeks I -have looked at a system called -S3QL, a locally -mounted network backed file system with the features I need.

- -

S3QL is a fuse file system with a local cache and cloud storage, -handling several different storage providers, any with Amazon S3, -Google Drive or OpenStack API. There are heaps of such storage -providers. S3QL can also use a local directory as storage, which -combined with sshfs allow for file storage on any ssh server. S3QL -include support for encryption, compression, de-duplication, snapshots -and immutable file systems, allowing me to mount the remote storage as -a local mount point, look at and use the files as if they were local, -while the content is stored in the cloud as well. This allow me to -have a backup that should survive fire. The file system can not be -shared between several machines at the same time, as only one can -mount it at the time, but any machine with the encryption key and -access to the storage service can mount it if it is unmounted.

- -

It is simple to use. I'm using it on Debian Wheezy, where the -package is included already. So to get started, run apt-get -install s3ql. Next, pick a storage provider. I ended up picking -Greenqloud, after reading their nice recipe on -how -to use S3QL with their Amazon S3 service, because I trust the laws -in Iceland more than those in USA when it come to keeping my personal -data safe and private, and thus would rather spend money on a company -in Iceland. Another nice recipe is available from the article -S3QL -Filesystem for HPC Storage by Jeff Layton in the HPC section of -Admin magazine. When the provider is picked, figure out how to get -the API key needed to connect to the storage API. With Greencloud, -the key did not show up until I had added payment details to my -account.

- -

Armed with the API access details, it is time to create the file -system. First, create a new bucket in the cloud. This bucket is the -file system storage area. I picked a bucket name reflecting the -machine that was going to store data there, but any name will do. -I'll refer to it as bucket-name below. In addition, one need -the API login and password, and a locally created password. Store it -all in ~root/.s3ql/authinfo2 like this: - -

-[s3c]
-storage-url: s3c://s.greenqloud.com:443/bucket-name
-backend-login: API-login
-backend-password: API-password
-fs-passphrase: local-password
-

- -

I create my local passphrase using pwget 50 or similar, -but any sensible way to create a fairly random password should do it. -Armed with these details, it is now time to run mkfs, entering the API -details and password to create it:

- -

-# mkdir -m 700 /var/lib/s3ql-cache
-# mkfs.s3ql --cachedir /var/lib/s3ql-cache --authfile /root/.s3ql/authinfo2 \
-  --ssl s3c://s.greenqloud.com:443/bucket-name
-Enter backend login: 
-Enter backend password: 
-Before using S3QL, make sure to read the user's guide, especially
-the 'Important Rules to Avoid Loosing Data' section.
-Enter encryption password: 
-Confirm encryption password: 
-Generating random encryption key...
-Creating metadata tables...
-Dumping metadata...
-..objects..
-..blocks..
-..inodes..
-..inode_blocks..
-..symlink_targets..
-..names..
-..contents..
-..ext_attributes..
-Compressing and uploading metadata...
-Wrote 0.00 MB of compressed metadata.
-#

- -

The next step is mounting the file system to make the storage available. - -

-# mount.s3ql --cachedir /var/lib/s3ql-cache --authfile /root/.s3ql/authinfo2 \
-  --ssl --allow-root s3c://s.greenqloud.com:443/bucket-name /s3ql
-Using 4 upload threads.
-Downloading and decompressing metadata...
-Reading metadata...
-..objects..
-..blocks..
-..inodes..
-..inode_blocks..
-..symlink_targets..
-..names..
-..contents..
-..ext_attributes..
-Mounting filesystem...
-# df -h /s3ql
-Filesystem                              Size  Used Avail Use% Mounted on
-s3c://s.greenqloud.com:443/bucket-name  1.0T     0  1.0T   0% /s3ql
-#
-

- -

The file system is now ready for use. I use rsync to store my -backups in it, and as the metadata used by rsync is downloaded at -mount time, no network traffic (and storage cost) is triggered by -running rsync. To unmount, one should not use the normal umount -command, as this will not flush the cache to the cloud storage, but -instead running the umount.s3ql command like this: - -

-# umount.s3ql /s3ql
-# 
-

- -

There is a fsck command available to check the file system and -correct any problems detected. This can be used if the local server -crashes while the file system is mounted, to reset the "already -mounted" flag. This is what it look like when processing a working -file system:

- -

-# fsck.s3ql --force --ssl s3c://s.greenqloud.com:443/bucket-name
-Using cached metadata.
-File system seems clean, checking anyway.
-Checking DB integrity...
-Creating temporary extra indices...
-Checking lost+found...
-Checking cached objects...
-Checking names (refcounts)...
-Checking contents (names)...
-Checking contents (inodes)...
-Checking contents (parent inodes)...
-Checking objects (reference counts)...
-Checking objects (backend)...
-..processed 5000 objects so far..
-..processed 10000 objects so far..
-..processed 15000 objects so far..
-Checking objects (sizes)...
-Checking blocks (referenced objects)...
-Checking blocks (refcounts)...
-Checking inode-block mapping (blocks)...
-Checking inode-block mapping (inodes)...
-Checking inodes (refcounts)...
-Checking inodes (sizes)...
-Checking extended attributes (names)...
-Checking extended attributes (inodes)...
-Checking symlinks (inodes)...
-Checking directory reachability...
-Checking unix conventions...
-Checking referential integrity...
-Dropping temporary indices...
-Backing up old metadata...
-Dumping metadata...
-..objects..
-..blocks..
-..inodes..
-..inode_blocks..
-..symlink_targets..
-..names..
-..contents..
-..ext_attributes..
-Compressing and uploading metadata...
-Wrote 0.89 MB of compressed metadata.
-# 
-

- -

Thanks to the cache, working on files that fit in the cache is very -quick, about the same speed as local file access. Uploading large -amount of data is to me limited by the bandwidth out of and into my -house. Uploading 685 MiB with a 100 MiB cache gave me 305 kiB/s, -which is very close to my upload speed, and downloading the same -Debian installation ISO gave me 610 kiB/s, close to my download speed. -Both were measured using dd. So for me, the bottleneck is my -network, not the file system code. I do not know what a good cache -size would be, but suspect that the cache should e larger than your -working set.

- -

I mentioned that only one machine can mount the file system at the -time. If another machine try, it is told that the file system is -busy:

- -

-# mount.s3ql --cachedir /var/lib/s3ql-cache --authfile /root/.s3ql/authinfo2 \
-  --ssl --allow-root s3c://s.greenqloud.com:443/bucket-name /s3ql
-Using 8 upload threads.
-Backend reports that fs is still mounted elsewhere, aborting.
-#
-

- -

The file content is uploaded when the cache is full, while the -metadata is uploaded once every 24 hour by default. To ensure the -file system content is flushed to the cloud, one can either umount the -file system, or ask S3QL to flush the cache and metadata using -s3qlctrl: - -

-# s3qlctrl upload-meta /s3ql
-# s3qlctrl flushcache /s3ql
-# 
-

- -

If you are curious about how much space your data uses in the -cloud, and how much compression and deduplication cut down on the -storage usage, you can use s3qlstat on the mounted file system to get -a report:

- -

-# s3qlstat /s3ql
-Directory entries:    9141
-Inodes:               9143
-Data blocks:          8851
-Total data size:      22049.38 MB
-After de-duplication: 21955.46 MB (99.57% of total)
-After compression:    21877.28 MB (99.22% of total, 99.64% of de-duplicated)
-Database size:        2.39 MB (uncompressed)
-(some values do not take into account not-yet-uploaded dirty blocks in cache)
-#
-

- -

I mentioned earlier that there are several possible suppliers of -storage. I did not try to locate them all, but am aware of at least -Greenqloud, -Google Drive, -Amazon S3 web serivces, -Rackspace and -Crowncloud. The latter even -accept payment in Bitcoin. Pick one that suit your need. Some of -them provide several GiB of free storage, but the prize models are -quite different and you will have to figure out what suits you -best.

- -

While researching this blog post, I had a look at research papers -and posters discussing the S3QL file system. There are several, which -told me that the file system is getting a critical check by the -science community and increased my confidence in using it. One nice -poster is titled -"An -Innovative Parallel Cloud Storage System using OpenStack’s SwiftObject -Store and Transformative Parallel I/O Approach" by Hsing-Bung -Chen, Benjamin McClelland, David Sherrill, Alfred Torrez, Parks Fields -and Pamela Smith. Please have a look.

- -

Given my problems with different file systems earlier, I decided to -check out the mounted S3QL file system to see if it would be usable as -a home directory (in other word, that it provided POSIX semantics when -it come to locking and umask handling etc). Running -my -test code to check file system semantics, I was happy to discover that -no error was found. So the file system can be used for home -directories, if one chooses to do so.

- -

If you do not want a locally file system, and want something that -work without the Linux fuse file system, I would like to mention the -Tarsnap service, which also -provide locally encrypted backup using a command line client. It have -a nicer access control system, where one can split out read and write -access, allowing some systems to write to the backup and others to -only read from it.

- -

As usual, if you use Bitcoin and want to show your support of my -activities, please send Bitcoin donations to my address -15oWEoG9dUPovwmUL9KWAnYRtNJEkP1u1b.

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- - - Tags: debian, english, personvern, sikkerhet. - - -
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