Data Storage Flashcards
What happens to storage costs over time?
They decrease
VCF
variable content file
Describes the management of data that may change after initial storage
FCF
fixed content file
Describes storage of data that will not change once stored
How much of the total stored image-related data does VCF make up?
5%
radiology information system (RIS), hospital information system
databases, and the demographic database of the PACS
Examples of VCF that make up the 5% of stored image-related data
How much of the total stored image-related data does FCF make up and what kind of “objects” are they made up of??
95%
DICOM (images, structured reports, and curves)
What is the typical storage for image data?
Storage on the aquisition modality (1+ days), followed by..
Forwarding an image copy from the modality to “Tier 1 storage”
What type of storage is “Tier 1” storage?
on-line
Who typically manages Tier 1 storage?
PACS
How long are images stored in Tier 1 storage?
3-15+ months (dependent upon clinical setting)
Upon receiving an imaging study in the Tier 1 storage system, what does PACS do?
- Verifies the information in the DICOM header against the information in RIS
- Forwards a copy of the study to “Tier 2” Storage
How long will a study remain in “Tier 2” storage?
For the duration of its legal life
Are data tiers the same as storage tiers?
No
How can each storage tier be described?
- On-line storage
- long-term storage
- Disaster Recovery
How many copies of ePHI are required by HIPAA?
Two
What can affect storage requirements for radiologic studies?
– Image size
– Number of images
– Slice thickness
– Protocols
– Sequences
– Modality vendor
What affect do contrast studies have on storage requirements?
They increase storage requirements substantially
What considerations are important when choosing data storage options?
- Outside images imported into PACS
- To consider for growth (facility, new modalities, or increased pt volume)
Depending on the local, state, or
federal statutes, ePHI must be retained in its original form (from
which diagnosis was made) for how long?
5-7 years (or longer)
How long may the ePHI of minors be required to be saved for?
Until the minor is of 21 years (or older depending on when the ePHI was acquired)
What factors affect the retention period of ePHI?
● the type
● the age of the individual
● federal statute
● Varies by state and type of provider
● state’s statute of
limitations
● Mammography has special regulations
How long after a person dies must ePHI be retained?
Generally a minimum of 2 years, but may vary by state
What is the minimum retention period for mammography studies?
5 years
What is the most cost-effective way to manage outdated ePHI?
Retain the PHI permanately
(it is too time consuming, due to complex governing, to make it worthwhile)
What parameters are considered when selecting Storage Media?
Functionality, Response time, Storage capacity, Longevity, Total Cost of Ownership (TCO), Durability, and Compliance Features
TCO
Total Cost of Ownership
the total cost of purchasing and supporting the storage management system and includes hardware, software, maintenance and
licensing fees, personnel, utilities, space, and information migration costs
Optical Media
Used primarily to provide a transportable copy of individual patient study and
as a low-cost, long-term storage, and disaster recovery media
WORM format
Write Once Read Many format
What kind of media is used by most storage today?
Spinning Magnetic Disc (Also known as Hard Drive Disc (HDD))
RAID
Redundant Array of Independent Disks
Prevents one disc failure from causing a loss of data by writing parity data across the array of discs
What is the downside of RAID?
The parity data takes up some storage space; therefore reducing it
Can RAID be used to back data up?
No
DAS
Direct attached storage
What is direct attached storage?
Simplest and least expensive storage technology where computer (server) is
directly attached to storage device such as RAID or tape system
What is the downside of DAS
Decreased storage availability, decreased scalability, inability to automate backup, and minimized planned system downtime
NAS
Network attached storage
What is NAS?
a file-based storage system with management software that is 100%
dedicated to serving files over a network
Why was NAS developed?
to address the inherent weaknesses of a server-based infrastructure
such as DAS
What does NAS eliminate?
the need for the server supporting storage and responding to
read/write responsibilities
What are some benefits of NAS?
simple and cost-effective
improved performance and productivity
data protection features
Ability to consolidate DAS resources
Scalabilty
SAN
storage area network
What is SAN?
a high performance storage network
that transfers data between servers and storage devices, separate from the local area network
How does SAN differ from DAS and NAS?
SAN moves data at the block level rather than at the file level
as does DAS and NAS
(ideal for moving data in large quantities)
Since the SAN operates on a block level and workstations operate at the file level, the PACS or other application must provide a what?
a block level to file level conversion
How is a SAN better than DAS and NAS?
- Performance
- 24/7 data availability
- Reliability, with a high degree of fault tolerance
- Scalability
- Data protection
- Storage virtualization
FC
Fiber Channel
What is a FC?
a gigabit-speed network technology used primarily for storage networking
What does the special cabling in FC do?
It enables FC to move large volumes of data without the distance
and bandwidth limitations of SCSI
What does a Hybrid SAN/NaSs do?
– Adds file interface to SAN
– Supports NAS standards
– Leverages a common storage infrastructure
iSCSI
Internet Small Computer System Interface
How does iSCSI differ from FC?
it uses IP networks rather than fiber channel to transmit data
Which is less costly, iSCSI or FC?
iSCSI, because FC requires special-purpose cabling; meanwhile iSCSI can run on existing network infrastructure
What kind of data storage and retrieval is made possible by iSCSI?
remote and independent storage
systems because IP networks such as LANs, WANs, and the Internet are
widely available
What are some key characteristics of cloud-based storage?
● Cloud storage is service based
● It is scalable and elastic
● It is shared
● Is metered by use.
● Applies the standards of Internet technologies
ASP
Application Service Provider
What are some characteristics of ASP?
– These ASP contracts can be structured as a SaaS or an IaaS model.
– Contract imposes a charge per study and/or a fxed monthly recurring charge.
– May be penalties for exceeding contracted study volumes.
VNA
Vendor Neutral Archive
What are some reasons to compress medical images?
Decrease transmission times
for medical images
– Decrease storage requirements
for medical images
– Decrease bandwidth requirements for the transmission of
medical images
– Reduce cost for storage management and infrastructure
What is lossless compression?
Digital data compression in which all the original data information is preserved and can be completely reconstituted
RLE
Run length encoding
How does RLE decrease image size?
Uses the redundancy within the image
Replaces sequences of the same data values within a file
by a count number and a single value
Lossy Compression
Methods of digital compression in
which the original information cannot
be completely reconstituted
What is the primary use for lossy compression?
for web distribution of images to the enterprise for
review purposes rather than primary interpretation
What is the primary justification for compressing FCF DICOM objects?
reducing
the time to transmit an image from one location to another
How does compressing FCF DICOM objects affect storage requirements?
it reduces them while also reducing cost and improving productivity
How must lossless compressed studies be stored?
In lossless compressed format
What is the problem with proprietary compression formats?
Will negatively impact interoperability of images and data migration
Can lock you into your current PACS vendor
Which of the following is an advantage of departmental storage over enterprise
storage?
(a) Vendor independence and best-of-breed purchasing
(b) Reduced cost of hardware and licensing fees
(c) Ease of providing redundancy
(d) Ease of initial setup
D
Regarding datacenters, which of the following is true?
(a) Tier 4 is the highest Tier rating for datacenters.
(b) The IT Department is responsible for specifying the characteristics of the
resources and the availability requirements.
(c) Power and cooling represent a small cost fraction of datacenter costs.
(d) 24/7 information availability is desirable, but not necessary.
B
Which of the following is not a form of network storage?
(a) RAID
(b) SAN
(c) NAS
(d) VNA
(e) Cloud
E
A Tier 4 datacenter with a guaranteed availability of 99.995% allows for how
much downtime per year?
(a) None
(b) 5.25 minutes/year
(c) 26.28 minutes/year
(d) 52.56 minutes/year
D
