Backups

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The CS department now hosts user data on ZFS, a filesystem that includes native support for snapshots. We take snapshots of all of our partitions every 6 hours, giving us 4 snapshots every day. These snapshots are stored locally as well as backed up to an offsite location. Users can access the snapshots of their partition, here you can find backups of your home directory.

So for example, if my home directory is /zf15/ktm5j then the snapshots for my partition live in /zf15/.zfs

This can be confusing because not only is this a hidden directory (hidden files/directories start with '.' in Unix) but you cannot see this directory even if you are looking for hidden directories. However this directory does exist and you are able to cd into it.

ktm5j@applecake /net/zf15/ktm5j $ cd /zf15
ktm5j@applecake /zf15 $ ls -a                                                       <--  Note that /zf15/.zfs isn't seen here
.        cd3rg     ems6v   jg5bf       lw3mz         pw4kz   sy4ma     wm5a
..       ci2016    es9bt   jw5g        lx3y          py3nu   tbt8k     yf5mr
aa5yf    cj7an     events  jwd         mfe4n         rb8ge   testuser  ym4gr
acg8z    cmh3g     fls4t   jz8bw       mkw3m         rc7ne   tg8be     yp5fd
ap8hf    cmh5mm    gr5yf   kcg2m       mr5ba         rg3ut   thn2c     yy2ev
ar9ch    cs.admin  gs5eg   kg8h        nae5c         rj4uf   tjt7a     yz5ea
as5cu    cx3wb     hl2uc   klf2bf      nbs4xa        rr2by   tl3xd     yz8bk
as5ec    dcr4f     hl4fb   ktm5j       office_staff  sa9sa   tm9bc     zc4hs
atl9gz   df5ah     hnp9uh  linklab     oj2zf         sd4tx   tpd5bf    zw5sx
backups  dka5ns    hw7ww   lmn7z       ow3fq         sew2ag  tw5zu     zx8sb
bhp6a    eds5h     hz2fq   @LongLink   pgh5a         sks6bu  tw8cb
bjd5v    ejs3s     jcc9s   lost+found  pp2df         sm5fd   txl5gd
bth3fb   ekw7ej    jed4h   lrj8me      pr2sn         sp4et   vvp2da
ktm5j@applecake /zf15 $ cd /zf15/.zfs                                               <--  However we can still enter the .zfs directory
ktm5j@applecake /zf15/.zfs $ ls
shares  snapshot

From here we can look in the snapshot/ directory and we will see the the zf15 snapshots

ktm5j@applecake /zf15/.zfs $ cd snapshot/
ktm5j@applecake /zf15/.zfs/snapshot $ ls
08.01.17-00  08.04.17-00  08.07.17-00  08.10.17-00  08.13.17-00  08.16.17-00
08.01.17-06  08.04.17-06  08.07.17-06  08.10.17-06  08.13.17-06  08.16.17-06
08.01.17-12  08.04.17-12  08.07.17-12  08.10.17-12  08.13.17-12  08.16.17-12
08.01.17-18  08.04.17-18  08.07.17-18  08.10.17-18  08.13.17-18  08.16.17-18
08.02.17-00  08.05.17-00  08.08.17-00  08.11.17-00  08.14.17-00  08.17.17-00
08.02.17-06  08.05.17-06  08.08.17-06  08.11.17-06  08.14.17-06  08.17.17-06
08.02.17-12  08.05.17-12  08.08.17-12  08.11.17-12  08.14.17-12  08.17.17-12
08.02.17-18  08.05.17-18  08.08.17-18  08.11.17-18  08.14.17-18  08.17.17-18
08.03.17-00  08.06.17-00  08.09.17-00  08.12.17-00  08.15.17-00  08.18.17-00
08.03.17-06  08.06.17-06  08.09.17-06  08.12.17-06  08.15.17-06  08.18.17-06
08.03.17-12  08.06.17-12  08.09.17-12  08.12.17-12  08.15.17-12  08.18.17-12
08.03.17-18  08.06.17-18  08.09.17-18  08.12.17-18  08.15.17-18

Each of these directories are snapshots that you can enter to find a "copy" of your partition at a certain date, the last two digits of these date stamps are the hour of the snapshot (eg 06 is 6:00 am, 18 is 6:00 pm). I can cd into /zf15/.zfs/snapshot/08.12.17-12/ktm5j/ and find my home directory as it was at 12:00 pm on 8/12 2017.