DokuWiki

Your Flexstorage storage share will be migrated to our new platform dubbed Rstore. Details are below. Once you have tested the new environment we need to coordinate a final update from Flexstorage to Rstore before you formally switch over.

Our current platform to provide disk storage capacity for users and groups is called Flexstorage. In this model users and groups purchase storage as needed for backup, replication and/or snapshosts. Our next platform will be called Rstore (stands for remote or research storage) and in this model disk space is allocated to users and groups upon request. Both platforms are made up of lots of slow spinning disks and should not be relied on for performance. A storage advisory group will evaluated the requests, possibly twice a year.

You will use your Wesleyan Active Directory (AD) credentials, that is, the username/password combination used to access all other Wesleyan services. There will be two service addresses: rstore0.wesleyan.edu and rstore2.wesleyan.edu. These addresses are each backed with a pair of integrated storage and server modules (rstoresrv[0&1].wesleyan.edu for rstore0 and rstoresrv[2&3].wesleyan.edu for rstore2). The service addresses will point to the primary member of each pair. During a fail over event the secondary will become the primary and handle the traffic for that service address. The failed primary, after being fixed, will then resurface as the secondary member.

There are several ways to access your contents either by logging in or mounting the shares. More information is provided below with specifics for your share.

Each primary/secondary pair contains a /home directory that is kept in sync. This is solely for SSH access. Users /home quotas are very small (10 MB) and should only be used for scripts for example. Each primary/secondary's disk array is carved up in into four data filesystems (/data/1, /data/2, /data3 and /data/4). Shares will be distributed across the four 26 TB data filesystems allowing all shares room for growth.

Replication is duplicating data on primary member to be in sync with data on secondary member. In the event of a fail over, the contents are available on short notice. If a file is corrupt or missing on primary, it will be so on secondary following a replication event. The secondary members within each pair nightly replicate any new data from the primary via a pulling action. The frequency of “pulling” is described as nightly but depending on volume of delta changes can span more than 24 hours. This happens for all four data filesystems within each pair.

Only the shares located on the third data filesystem (/data/3), in addition to replication, will perform snapshots. This happens on both primary and secondary, locally, from for example /data/3/share_name/ to /data/4/snapshots/share_name/, and also happens nightly. Snapshots are point-in-time comparisons of the share contents. Snapshots will be kept for: 6 daily, 4 weekly, 2 monthly. Thus if a file is deleted or corrupt it can be restored. This only happens for shares on /data/3 while we can sustain such disk usage requirements.

Note: Because of replication, large reorganizations of content areas (250+ gb or 10,000+ files) causes a lot of deletions first, then recopying. Please describe in detail what needs to be moved where and we can perform those actions on both primary and secondary members avoiding this.

Note: For very large filesystems whose contents does not change, the replication can take a long time and is typically unnecessary after first copy event. Share owners can control what gets replicated, or not, by staging a file in the top level share folder named rsync.incl or rsync.excl. These files contain lines of absolute paths to the folders to be either excluded or included during replication. For example: /data/1/share_name/projects/2005 (do not use weird characters or spaces). An include file only replicates those folders and an exclude file replicates the whole share but skips the listed folders.

Your content is protected using these methods:

• When the content was transferred from Flexstorage to Rstore the -c option of rsync was used meaning perform a checksum check guaranteeing that both files have the same unique finger print.
• Once copied to Rstore disk arrays the content is protected with redundant array of independent disk technology, in our case RAID 60. This technique keeps multiple copies of data chunks so that failed disks can be repaired. RAID 60 can withstand two simultaneous disk failures.
• RAID cards managing the arrays continually scrub and test the disks for sign of probable near future failure events thus reducing actual failures.
• In the event of a primary catastrophic failure of a member in a pair, the content is available on the secondary member in a state defined by last replication event.
• In an accidental deletion of content in shares in /data/3 (ONLY), there will be snapshots available for restoration (daily, weekly, monthly).
• Both primary/secondary members reside in the same data center but not in the same rack location wise.
• Both primary/secondary members are dual source powered (utility power and enterprise UPS)
• Upon deployment of your share, checksums will be calculated for each file on both primary and secondary members. These “hashdeep” signatures (file size, two different checksums (MD5, SHA-256), and absolute path to file) will be stored in a text file. That text file can be used in an audit to find out if anything about these files has changed and a report can be provided. If this gets automated will need to be assessed in the future.

• Your share's service address: rstore0.wesleyan.edu
• Your share's location: /data/[1-4]
• Your share's name: SHARE_NAME
• Your share's default permissions are:
  • share owner (SHARE_OWNER) rwx, share group (SHARE_GROUP) rwx, others none
  • share members own their own folders and files they create
  • share members have group access to folders and files created
    • This default policy can be changed to a certain extent

• SSH access
  • open any ssh client and connect to service address, you end up in /home/username
  • then change directories (cd /location/to/share) to your share location
  • view contents (ls -l) etc
    • These are not computational servers but running maintenance scripts is allowed
    • If you will be running programs that will take a long time please notify us

• Samba access
• Windows users, map a network drive and use your AD credentials
  • \\service_address.wesleyan.edy\SHARE_NAME
• Max users, mount a samba share
  • smb:service_address.wesleyan.edu/SHARE_NAME *
    Back