Oracle has pulled a Scrooge on us, voiding our November order for 320 TB of Thors - before they were discontinued. We didn't make it in time. Now we need to explore options and plans for our disk storage. Also to get us through this particular crunch - we have some 55 TB free at the time of writing, and owe 128 TB to KIPAC and BABAR!
Possible elements of the plan:
- clean up existing space
- explore replacing disks in existing fileservers with 2 TB ones
- find a new vendor(s)
- change storage model
Clean up
We have 1.05 PB of space in xrootd now. Some 640 TB of that is taken up by L1, and 90% of that space is occupied by recon, svac and cal tuples.
[Tom]
Data current as of 12/8/2010.
Current xroot holdings:
Total Space |
1.043 TB |
35 servers (wain006 removed) |
xrootd overhead |
0.021 TB |
(disk 'buffer' space) |
Available Space |
1.022 TB |
|
Current usage:
<ac:structured-macro ac:name="unmigrated-wiki-markup" ac:schema-version="1" ac:macro-id="933b4d85-f359-4c8d-a232-6931b1163315"><ac:plain-text-body><![CDATA[ |
path |
size [TB] |
#files |
]]></ac:plain-text-body></ac:structured-macro> |
|---|---|---|---|---|
/glast/Data |
785 |
807914 |
||
/glast/Data/Flight |
767 |
792024 |
||
/glast/Data/Flight/Level1/ |
713 |
535635 |
||
/glast/mc |
82 |
11343707 |
||
/glast/mc/ServiceChallenge/ |
56 |
6649775 |
||
/glast/Scratch |
51 |
358511 |
||
/glast/Data/Flight/Reprocess/ |
50 |
226757 |
||
/glast/level0 |
13 |
2020329 |
||
/glast/bt |
4 |
760384 |
||
/glast/test |
2 |
2852 |
||
/glast/scratch |
1 |
51412 |
||
/glast/mvmd5 |
0 |
738 |
||
/glast/admin |
0 |
108 |
||
/glast/ASP |
0 |
19072 |
Replacing Existing Disks
New Vendors
Two obvious candidates are in use at the Lab now: DDN by LCLS, and Dell el cheapo by ATLAS.
DDN
Dell
These are $160/TB, but low density.
Change Storage Model
The idea is to use HPSS as a storage layer to transparently retrieve xrootd files on demand. Wilko thinks the system can push 30-50 TB/day from tape. This is comparable to the rate needed for a merit reprocessing and so is thought not to be a major impediment. In this model, we would remove the big files from disk after making 2 tape copies. They would be retrieved back into a disk buffer when needed. So we would have a relatively fixed disk buffer, and a growing tape presence.