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RSTORE FAQ

Will be adding answers as we go along.

What is it?

Our current platform to provide disk storage capacity for users and groups is called Flexstorage. In this model users and groups would 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 used if performance is required.

How do I access it?

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 adresses: rstore0.wesleyan.edu and rstore2.wesleyan.edu. These targets 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 secondary.

There are several ways to access your contents either by logging in or moounting the shares. See below.

How is is configured?

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

The secondary members within each pair, nightly replicate any new data from the primary via a pulling action. Please note that if a file is missing on primary, the file will be deleted on secondary. The frequency of “pulling” is described as nightly but depending on volume of delta changes can span more than 24 hours, it is continuous. Thus happens for all four data filesystems.

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 /data/3/share_name to /data/4/snapshots/share_name and also happens nightly. Replication is duplicating data on primary member to be in sync with data on secondary member. In the of fail over, the contents are immediately available, but if a file is corrupt or missing, it will be so on both members following a replication event. Snapshots are point-in-time comparisong of the shares contents. This will be done nightly and 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.

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 and we can perform those actions on primary and secondary avoiding this.

Is my content safe?

Your content is protected using these methods:

  • When the data was transferred from source to target the -c option of rsync was used meaning perform a checksum check garateeing that both files have the same unique finger print.
  • Once copied to disk arrays the content is protected with redundant array of independent disk techonlogy, in our case RAID 60. This is a technique to keep multiple copies of data chunks so that failed disks can be repaired. RAID 60 can withstand two simultaneous disk failures.
  • RAID cards manging 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 failure of a member in a pair, the content is available on other member in a state since last replication even.
  • In an accidental deletion of content in shares in /data/3 (ONLY), will there be snapshots available for restoration.
  • Both primary/secondary members reside in the same data center but not in the same racks location wise.

How do I log in, mount?

  • your share is: /data/[1-4]/share_name
  • default share permissions are
    • share owners rwx, share group rwx, others none
    • share members own their own folders created
    • but group members have rwx access to folders and files


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cluster/135.1417640135.txt.gz · Last modified: 2014/12/03 15:55 by hmeij