Computer Architecture, Appendix D

1. Computer Architecture, Appendix D

Storage Systems

Computer Architecture, A Quantitative Approach, Fifth Edition,

John L. Hennessy and David A. Patterson, 2011.

---

-- When We are No More: How Digital Memory Will Shape Our Future, by Abby Smith Rumsey, 2016.
Excerpt: When distracted ... we fail to build the vital repertoire of knowledge and experience that may be of use to us in the future. And it is the future that is at stake. For memory is not about the past. It is about the future.

2. Access Time Gap

DRAM latency is about 100,000 times less than disk, but costs 30 to 150 times more per gigabyte.

Disk: 600 GB, $400, 200 MB/sec

DRAM: 4 GB, $200, 16,000 MB/sec (80 times faster than disk)

Bandwidth per GB: 12,000 times higher for DRAM

Bandwidth per dollar: 160 times higher

3. Access Time Gap - update

B. Warabak, Dec. 2016

4. Upload or Ship It?

Should You Upload or Ship Big Data to the Cloud?, Sachin Date, CACM, July 2016.

equation (1) (missing from the paper):

  TimeTransit_hours = 16;  TimeOverhead = 48;  SpeedIn_MB = 160;  SpeedOut_MB = 160;

  % ship it
  %
  TransferTime_hours =   VolumeContent_MB / (3600 * SpeedIn_MB)  + TimeTransit_hours
                       + VolumeContent_MB / (3600 * SpeedOut_MB) + TimeOverhead;

  % upload @ 100 Mbps
  %
  UploadTime_hours = VolumeContent_MB / (3600 * (100/8));

5. Upload or Ship It - Zoom

6. Genomic Data

Computational Biology in the 21st Century, Bonnie Berger, Noah M. Daniels, and Y. William Yu, CACM, August 2016.

7. RAID

8. RAID Levels 4, 5, 6

https://en.wikipedia.org/wiki/Standard_RAID_levels

9. RAID Level 6 Example

10. Linux mdadm Example

# df
Filesystem     1K-blocks     Used Available Use% Mounted on
/dev/md1        32858920  4738524  27785324  15% /
tmpfs            4024308      336   4023972   1% /dev/shm
/dev/md2        70429036 50379700  16465084  76% /home
/dev/sde1       70430128 57635932   9209892  87% /a
/dev/sdf1       61403764 23268544  35009432  40% /media/SD10
# mdadm --misc --detail /dev/md1
/dev/md1:
        Version : 1.0
  Creation Time : Sun May 27 17:03:43 2012
     Raid Level : raid1
     Array Size : 33516472 (31.96 GiB 34.32 GB)
  Used Dev Size : 33516472 (31.96 GiB 34.32 GB)
   Raid Devices : 2
  Total Devices : 2
    Persistence : Superblock is persistent

  Intent Bitmap : Internal

    Update Time : Tue Aug  9 09:34:48 2016
          State : clean
 Active Devices : 2
Working Devices : 2
 Failed Devices : 0
  Spare Devices : 0

           Name : vecr.ece.villanova.edu:1  (local to host vecr.ece.villanova.edu)
           UUID : 3ee16fb8:8ae32795:73708c46:69d25403
         Events : 6382

    Number   Major   Minor   RaidDevice State
       0       8        2        0      active sync   /dev/sda2
       1       8       18        1      active sync   /dev/sdb2
#