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Write once read many (WORM) describes a data storage device in which information, once written, cannot be modified. This write protection affords the assurance that the data cannot be tampered with once it is written to the device, excluding the possibility of data loss from human error, computer bugs, or malware.

On ordinary (non-WORM) data storage devices, the number of times data can be modified is limited only by the lifespan of the device, as modification involves physical changes that may cause wear to the device. The "read many" aspect is unremarkable, as modern storage devices permit unlimited reading of data once written.^{[Note 1]}

WORM protects the important files by keeping them safe and intact. It ensures the highest level of integrity and data security by eliminating the risk of important data from being deleted or modified. This way, the WORM helps to preserve the authenticity and safety of recorded data.

History

WORM drives preceded the invention of the CD-R, DVD-R and BD-R. An example was the IBM 3363.^[1] These drives typically used either a 5.1 in (13 cm) or a 12 in (30 cm) disc in a cartridge, with an ablative optical layer that could be written to only once, and were often used in places like libraries that needed to store large amounts of data. Interfaces to connect these to PCs also existed.

Punched cards and paper tape are obsolete WORM media. Although any unpunched area of the medium could be punched after the first write of the medium, doing so was virtually never useful. Read-only memory (ROM) is also a WORM medium. Such memory may contain the instructions to a computer to read the operating system from another storage device such as a hard disk. The non-technical end-user, however, cannot write the ROM even once but considers it part of the unchangeable computing platform.

WORM was utilized for Broker-dealer records within the Financial Industry Regulatory Authority and the U.S. Securities and Exchange Commission.

Current WORM drives

Once written to, the data on a once-writable optical disc can not be modified and the space is reserved.

The CD-R, DVD-R and BD-R optical discs for computers are common WORM devices. On these discs, no region of the disc can be recorded a second time. Through packet writing, which uses the Universal Disk Format (UDF) file system, these discs often use a file system that permits additional files, and even revised versions of a file by the same name, to be recorded in a different region of the disc. To the user, the disc appears to allow additions and revisions until all the disk space is used.

The SD card and microSD card spec allows for multiple forms of write-protection. The most common form, only available when using a full-size SD card, provides a physical write protection switch which allows the user to advise the host card reader to disallow write access. This does not protect the data on the card if the card reader hardware is not built to respect the write protection switch.^[2]

Multiple vendors beginning in the early 2000s developed Magnetic WORM devices. These archival grade storage devices utilize a variation of RAID and magnetic storage technologies to secure data from unauthorized alteration or modification at both the hardware and software levels. As the cost of magnetic (and solid-state) storage has decreased, so has the cost for these archival storage technologies. These technologies are almost always integrated directly into a content/document management system that manages retention schedules and access controls, along with document level history.^[3]^[4]

There are multiple vendors providing Magnetic Storage technologies including NetApp,^[5] EMC Centera,^[6] KOM Networks,^[7] and others. In 2013, GreenTec-USA, Inc. developed WORM hard disk drives in capacities of 3 TB and greater. Prevention of rewrite is done at the physical disk level and cannot be modified or overridden by the attached computer.^[8]^[9]

Research

In recent years^[when?] there has been a renewed interest in WORM based on organic components, such as PEDOT:PSS^[10]^[11] or other polymers such as PVK^[12] or PCz.^[13] Organic WORM devices, considered organic memory, could be used as memory elements for low-power RFID tags.^[14]

Notes

^ Historical exceptions include time-limited discs such as Flexplay, designed for short-term rental of movies; and early non-volatile memory technologies such as magnetic-core memory and bubble memory, from which reading data also erased it.

References

^ "IBM 3363 optical WORM drive". November 21, 1987 – via Computer History Museum Archive.
^ "Simplified Specifications - SD Association, version 3.10, Part 1, Physical Layer, section 4.3.6" Write Protect Management"". www.sdcard.org. Retrieved 2019-04-11.
^ http://www.aiim.org/documents/standards/ARP1-2009.pdf ^{[dead link‍]}
^ "Analysis, Selection, and Implementation of Electronic Document Management Systems (EDMS)" (PDF). Association for Information and Image Management. 2009. Archived (PDF) from the original on 2009-12-29.
^ "SnapLock: WORM Compliance – Data Compliance". NetApp.
^ EMC Centers emc.com
^ "Products Overview". Archived from the original on 2012-02-17.
^ "GreenTec-USA, Inc. WORM Read Only Disk Drives" http://www.greentec-usa.com
^ "Best Practices to Secure Data from Modification: Eliminating the Risk to Online Content" http://greentec-usa.com/wp/GreenTec-WORM-Whitepaper.pdf
^ Möller, Sven; Perlov, Craig; Jackson, Warren; Taussig, Carl; Forrest, Stephen R. (2003). "A polymer/Semiconductor write-once read-many-times memory". Nature. 426 (6963): 166–169. Bibcode:2003Natur.426..166M. doi:10.1038/nature02070. PMID 14614502. S2CID 4337352.
^ Smith, Shawn; Forrest, Stephen R. (14 June 2004). "Smith and Forrest "A low switching voltage organic-on-inorganic heterojunction memory element utilizing a conductive polymer fuse on a doped silicon substrate"". Applied Physics Letters. 84 (24): 5019–5021. doi:10.1063/1.1763632. Retrieved 21 November 2024.
^ Lin, Jian; Ma, Dongge (3 September 2008). "Lin and Ma "Realization of write-once-read-many-times memory devices based on poly(N-vinylcarbazole) by thermally annealing"". Applied Physics Letters. 93 (9). doi:10.1063/1.2975157. Retrieved 21 November 2024.
^ Teo, E. Y. H.; Zhang, C.; Lim, S. L.; Kang, E.; Chan, D. S. H.; Zhu, C. (May 2009). "An Organic-Based Diode–Memory Device With Rectifying Property for Crossbar Memory Array Applications". IEEE Electron Device Letters. 30 (5): 487–489. Bibcode:2009IEDL...30..487Y. doi:10.1109/LED.2009.2017387. ISSN 0741-3106. S2CID 19858062.
^ "Holst Centre reports major step towards organic RFID"

[1] Historical exceptions include time-limited discs such as Flexplay, designed for short-term rental of movies; and early non-volatile memory technologies such as magnetic-core memory and bubble memory, from which reading data also erased it.

[2] "IBM 3363 optical WORM drive". November 21, 1987 – via Computer History Museum Archive.

[3] "Simplified Specifications - SD Association, version 3.10, Part 1, Physical Layer, section 4.3.6" Write Protect Management"". www.sdcard.org. Retrieved 2019-04-11.

[4] ttp://www.aiim.org/documents/standards/ARP1-2009.pdf ^{[dead link‍]}

[5] "Analysis, Selection, and Implementation of Electronic Document Management Systems (EDMS)" (PDF). Association for Information and Image Management. 2009. Archived (PDF) from the original on 2009-12-29.

[6] "SnapLock: WORM Compliance – Data Compliance". NetApp.

[7] EMC Centers emc.com

[8] "Products Overview". Archived from the original on 2012-02-17.

[9] "GreenTec-USA, Inc. WORM Read Only Disk Drives" http://www.greentec-usa.com

[10] "Best Practices to Secure Data from Modification: Eliminating the Risk to Online Content" http://greentec-usa.com/wp/GreenTec-WORM-Whitepaper.pdf

[11] Möller, Sven; Perlov, Craig; Jackson, Warren; Taussig, Carl; Forrest, Stephen R. (2003). "A polymer/Semiconductor write-once read-many-times memory". Nature. 426 (6963): 166–169. Bibcode:2003Natur.426..166M. doi:10.1038/nature02070. PMID 14614502. S2CID 4337352.

[12] Smith, Shawn; Forrest, Stephen R. (14 June 2004). "Smith and Forrest "A low switching voltage organic-on-inorganic heterojunction memory element utilizing a conductive polymer fuse on a doped silicon substrate"". Applied Physics Letters. 84 (24): 5019–5021. doi:10.1063/1.1763632. Retrieved 21 November 2024.

[13] Lin, Jian; Ma, Dongge (3 September 2008). "Lin and Ma "Realization of write-once-read-many-times memory devices based on poly(N-vinylcarbazole) by thermally annealing"". Applied Physics Letters. 93 (9). doi:10.1063/1.2975157. Retrieved 21 November 2024.

[14] Teo, E. Y. H.; Zhang, C.; Lim, S. L.; Kang, E.; Chan, D. S. H.; Zhu, C. (May 2009). "An Organic-Based Diode–Memory Device With Rectifying Property for Crossbar Memory Array Applications". IEEE Electron Device Letters. 30 (5): 487–489. Bibcode:2009IEDL...30..487Y. doi:10.1109/LED.2009.2017387. ISSN 0741-3106. S2CID 19858062.

[15] "Holst Centre reports major step towards organic RFID"

[Note 1]

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[2]

[3]

[4]

[5]

[6]

[7]

[8]

[9]

[10]

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+{{Short description|Type of data storage device}}
-'''Write once read many''' ('''WORM''') describes a [[data storage device]] in which information, once written, cannot be modified. This [[write protection]] affords the assurance that the [[data]] cannot be tampered with once it is written to the device.
+'''Write once read many''' ('''WORM''') describes a [[data storage device]] in which information, once written, cannot be modified. This [[write protection]] affords the assurance that the [[data]] cannot be tampered with once it is written to the device, excluding the possibility of [[data loss]] from [[human error]], [[computer bugs]], or [[malware]].
-On ordinary (non-WORM) data storage devices, the number of times data can be modified is limited only by the lifespan of the device, as modification involves physical changes that may cause wear to the device. The "read many" aspect is unremarkable, as modern storage devices permit unlimited reading of data once written.<ref group="Note">Historical exceptions include time-limited discs such as [[Flexplay]], designed for short-term rental of movies; and early [[non-volatile memory]] technologies such as [[magnetic-core memory]]  and [[bubble memory]], from which reading data also erased it.</ref>
+On ordinary (non-WORM) data storage devices, the number of times data can be modified is limited only by the lifespan of the device, as modification involves physical changes that may cause wear to the device. The "read many" aspect is unremarkable, as modern storage devices permit unlimited reading of data once written.<ref group="Note">Historical exceptions include time-limited discs such as [[Flexplay]], designed for short-term rental of movies; and early [[non-volatile memory]] technologies such as [[magnetic-core memory]] and [[bubble memory]], from which reading data also erased it.</ref>
 WORM protects the important files by keeping them safe and intact. It ensures the highest level of integrity and data security by eliminating the risk of important data from being deleted or modified. This way, the WORM helps to preserve the authenticity and safety of recorded data.
 ==History==
+{{See also|Magneto-optical drive}}
-WORM drives preceded the invention of the [[CD-R]] and [[DVD recordable|DVD-R]]. An example was the IBM 3363.<ref>[http://www.computerhistory.org/collections/accession/102671161 IBM 3363 Optical WORM drive]</ref> These drives typically used a {{convert|12|in|cm|abbr=on}} disk in a cartridge, with an [[Ablation|ablative]] optical layer that could be written to only once, and were often used in places like libraries that needed to store large amounts of data. Interfaces to connect these to PCs also existed.
+WORM drives preceded the invention of the [[CD-R]], [[DVD recordable|DVD-R]] and [[Blu-ray Disc recordable|BD-R]]. An example was the IBM 3363.<ref>{{Cite web|url=https://www.computerhistory.org/collections/catalog/102671161|title=IBM 3363 optical WORM drive|date=November 21, 1987|via=Computer History Museum Archive}}</ref> These drives typically used either a {{convert|5.1|in|cm|abbr=on}} or a {{convert|12|in|cm|abbr=on}} disc in a cartridge, with an [[Ablation|ablative]] optical layer that could be written to only once, and were often used in places like libraries that needed to store large amounts of data. Interfaces to connect these to PCs also existed.
-[[Punched card]]s and [[paper tape]] are obsolete WORM media.  Although any unpunched area of the medium could be punched after the first write of the medium, doing so was virtually never useful.  [[Read-only memory]] (ROM) is also a WORM medium.  Such memory may contain the instructions to a computer to read the [[operating system]] from another storage device such as a [[hard disk]].  The non-technical end-user, however, cannot write the ROM even once but considers it part of the unchangeable [[computing platform]].
+[[Punched card]]s and [[paper tape]] are obsolete WORM media. Although any unpunched area of the medium could be punched after the first write of the medium, doing so was virtually never useful. [[Read-only memory]] (ROM) is also a WORM medium. Such memory may contain the instructions to a computer to read the [[operating system]] from another storage device such as a [[hard disk]]. The non-technical end-user, however, cannot write the ROM even once but considers it part of the unchangeable [[computing platform]].
 WORM was utilized for [[Broker-dealer]] records within the [[Financial Industry Regulatory Authority]] and the [[U.S. Securities and Exchange Commission]].
 ==Current WORM drives==
+[[File:DVD-R.jpg|thumb|Once written to, the data on a once-writable optical disc can not be modified and the space is reserved.]]
-The [[CD-R]] and [[DVD-R]] optical disks for [[computer]]s were common WORM devices.  On these disks, no region of the disk can be recorded a second time.  However, these disks often use a [[file system]] based on [[ISO 9660]] that permits additional [[Computer file|files]], and even revised versions of a file by the same name, to be recorded in a different region of the disk.  To the user of the disk, the disk appears to allow additions and revisions until all the disk space is used.
+The [[CD-R]], [[DVD-R]] and [[BD-R]] [[optical disc]]s for [[computer]]s are common WORM devices. On these discs, no region of the disc can be recorded a second time. Through [[packet writing]], which uses the [[Universal Disk Format]] (UDF) file system, these discs often use a [[file system]] that permits additional [[Computer file|files]], and even revised versions of a file by the same name, to be recorded in a different region of the disc. To the user, the disc appears to allow additions and revisions until all the disk space is used.
-The [[SD card]] and microSD card spec allows for multiple forms of write-protection. The most common form, only available when using a full-size SD card, provides a "mechanical write protect switch" which allows the user to advise the host computer that the user wants the device to be treated as read-only. This does not protect the data on the card if the host is compromised.<ref>{{Cite web|url=https://www.sdcard.org/downloads/pls/index.html|title=Simplified Specifications - SD Association, version 3.10 , Part 1, Physical Layer, section 4.3.6" Write Protect Management"|website=www.sdcard.org|access-date=2019-04-11}}</ref> Another option is to set the WORM function into the firmware of the memory card so it will always run on WORM card mode by default. By using this option, it will not require to trigger an external software trigger to enable the WORM card function.<ref>{{Cite web|url=https://www.flexxon.com/write-once-read-many-worm-sd-microsd-cards/|title=Flexxon {{!}} SD & MicroSD Write-Once-Read-Many WORM Card|website=Flexxon|language=en-US|access-date=2019-07-22}}</ref>
+The [[SD card]] and microSD card spec allows for multiple forms of write-protection. The most common form, only available when using a full-size SD card, provides a physical write protection switch which allows the user to advise the host card reader to disallow write access. This does not protect the data on the card if the card reader hardware is not built to respect the write protection switch.<ref>{{Cite web|url=https://www.sdcard.org/downloads/pls/index.html|title=Simplified Specifications - SD Association, version 3.10, Part 1, Physical Layer, section 4.3.6" Write Protect Management"|website=www.sdcard.org|access-date=2019-04-11}}</ref>
-Multiple vendors beginning in the early 2000s developed Magnetic WORM devices. These archival grade storage devices utilize a variation of RAID and magnetic storage technologies to secure data from unauthorized alteration or modification at both the hardware and software levels. As the cost of magnetic (and solid-state) storage has decreased, so has the cost for these archival storage technologies. These technologies are almost always integrated directly into a content/document management system that manages retention schedules and access controls, along with document level history.<ref>http://www.aiim.org/documents/standards/ARP1-2009.pdf</ref><ref>{{cite web|last=|first=|date=2009|title=Analysis, Selection, and Implementation of Electronic Document Management Systems (EDMS)|url=http://www.aiim.org/documents/standards/ARP1-2009.pdf|url-status=live|archive-url=https://web.archive.org/web/20091229175151/http://www.aiim.org/documents/standards/ARP1-2009.pdf|archive-date=2009-12-29|access-date=|website=Association for Information and Image Management}}</ref>
+Multiple vendors beginning in the early 2000s developed Magnetic WORM devices. These archival grade storage devices utilize a variation of RAID and magnetic storage technologies to secure data from unauthorized alteration or modification at both the hardware and software levels. As the cost of magnetic (and solid-state) storage has decreased, so has the cost for these archival storage technologies. These technologies are almost always integrated directly into a content/document management system that manages retention schedules and access controls, along with document level history.<ref>http://www.aiim.org/documents/standards/ARP1-2009.pdf {{Dead link|date=February 2022}}</ref><ref>{{cite web|last=|first=|date=2009|title=Analysis, Selection, and Implementation of Electronic Document Management Systems (EDMS)|url=http://www.aiim.org/documents/standards/ARP1-2009.pdf|url-status=live|archive-url=https://web.archive.org/web/20091229175151/http://www.aiim.org/documents/standards/ARP1-2009.pdf|archive-date=2009-12-29|access-date=|website=Association for Information and Image Management}}</ref>
-There are multiple vendors providing Magnetic Storage technologies including NetApp,<ref>{{Cite web | url=http://www.netapp.com/us/products/protection-software/snaplock.aspx |title = SnapLock: WORM Compliance – Data Compliance |website=NetApp}}</ref> EMC Centera,<ref>http://www.emc.com/collateral/hardware/data-sheet/c931-emc-centera-cas-ds.pdf</ref> KOM Networks,<ref>https://www.komnetworks.com/products.html</ref> and others. In 2013, GreenTec-USA, Inc. developed WORM hard disk drives in capacities of 3&nbsp;TB and greater.  Prevention of rewrite is done at the physical disk level and cannot be modified or overridden by the attached computer.<ref>"GreenTec-USA, Inc. WORM Read Only Disk Drives" http://www.greentec-usa.com</ref><ref>"Best Practices to Secure Data from Modification: Eliminating the Risk to Online Content" http://greentec-usa.com/wp/GreenTec-WORM-Whitepaper.pdf</ref>
+There are multiple vendors providing Magnetic Storage technologies including NetApp,<ref>{{Cite web | url=http://www.netapp.com/us/products/protection-software/snaplock.aspx |title = SnapLock: WORM Compliance – Data Compliance |website=NetApp}}</ref> EMC Centera,<ref>[http://www.emc.com/collateral/hardware/data-sheet/c931-emc-centera-cas-ds.pdf EMC Centers] emc.com</ref> KOM Networks,<ref>{{cite web |url=https://www.komnetworks.com/products.html |url-status=dead |archive-url=https://web.archive.org/web/20120217203447/http://www.komnetworks.com/products.html |archive-date=2012-02-17 |title=Products Overview}}</ref> and others. In 2013, GreenTec-USA, Inc. developed WORM hard disk drives in capacities of 3&nbsp;TB and greater. Prevention of rewrite is done at the physical disk level and cannot be modified or overridden by the attached computer.<ref>"GreenTec-USA, Inc. WORM Read Only Disk Drives" http://www.greentec-usa.com</ref><ref>"Best Practices to Secure Data from Modification: Eliminating the Risk to Online Content" http://greentec-usa.com/wp/GreenTec-WORM-Whitepaper.pdf</ref>
-softWORM is a new generation of WORM solutions based on providing durability features through cryptographic techniques and algorithms implemented in the software. The representative of this solution class is the S<sup>3</sup>DOC<ref>{{Cite web | url=https://s3doc.com |title = S3DOC: software Durable Medium solution | website = BCHAIN PARTNER}}</ref>
 ==Research==
-In recent years there has been a renewed interest in WORM based on organic components, such as [[PEDOT:PSS]]<ref>{{Cite journal |doi = 10.1038/nature02070|pmid = 14614502|title = A polymer/Semiconductor write-once read-many-times memory|journal = Nature|volume = 426|issue = 6963|pages = 166–169|year = 2003|last1 = Möller|first1 = Sven|last2 = Perlov|first2 = Craig|last3 = Jackson|first3 = Warren|last4 = Taussig|first4 = Carl|last5 = Forrest|first5 = Stephen R.|bibcode = 2003Natur.426..166M}}</ref><ref>[http://apl.aip.org/resource/1/applab/v84/i24/p5019_s1 Smith and Forrest "A low switching voltage organic-on-inorganic heterojunction memory element utilizing a conductive polymer fuse on a doped silicon substrate"]</ref> or other polymers such as PVK<ref>[http://apl.aip.org/resource/1/applab/v93/i9/p093505_s1 Lin and Ma "Realization of write-once-read-many-times memory devices based on poly(N-vinylcarbazole) by thermally annealing"]</ref> or PCz.<ref>{{Cite journal|last=Teo|first=E. Y. H.|last2=Zhang|first2=C.|last3=Lim|first3=S. L.|last4=Kang|first4=E.|last5=Chan|first5=D. S. H.|last6=Zhu|first6=C.|date=May 2009|title=An Organic-Based Diode–Memory Device With Rectifying Property for Crossbar Memory Array Applications|journal=IEEE Electron Device Letters|volume=30|issue=5|pages=487–489|doi=10.1109/LED.2009.2017387|issn=0741-3106|bibcode=2009IEDL...30..487Y}}</ref> Organic WORM devices, considered organic memory, could be used as memory elements for low-power [[RFID]] tags.<ref>[http://www2.imec.be/be_en/press/imec-news/archive-2009/holst-centre-reports-major-step-towards-organic-rfid.html "Holst Centre reports major step towards organic RFID"]</ref>
+In recent years{{When|date=August 2023}} there has been a renewed interest in WORM based on organic components, such as [[PEDOT:PSS]]<ref>{{Cite journal |doi = 10.1038/nature02070|pmid = 14614502|title = A polymer/Semiconductor write-once read-many-times memory|journal = Nature|volume = 426|issue = 6963|pages = 166–169|year = 2003|last1 = Möller|first1 = Sven|last2 = Perlov|first2 = Craig|last3 = Jackson|first3 = Warren|last4 = Taussig|first4 = Carl|last5 = Forrest|first5 = Stephen R.|bibcode = 2003Natur.426..166M|s2cid = 4337352}}</ref><ref>{{Cite journal |title=Smith and Forrest "A low switching voltage organic-on-inorganic heterojunction memory element utilizing a conductive polymer fuse on a doped silicon substrate" |url=https://pubs.aip.org/aip/apl/article-abstract/84/24/5019/508686/A-low-switching-voltage-organic-on-inorganic?redirectedFrom=fulltext |access-date=21 November 2024 |journal=Applied Physics Letters| date=14 June 2004 | volume=84 | issue=24 | pages=5019–5021 | doi=10.1063/1.1763632 | last1=Smith | first1=Shawn | last2=Forrest | first2=Stephen R. }}</ref> or other polymers such as PVK<ref>{{Cite journal |title=Lin and Ma "Realization of write-once-read-many-times memory devices based on poly(N-vinylcarbazole) by thermally annealing" |url=https://pubs.aip.org/aip/apl/article-abstract/93/9/093505/765130/Realization-of-write-once-read-many-times-memory?redirectedFrom=fulltext |access-date=21 November 2024 |journal=Applied Physics Letters| date=3 September 2008 | volume=93 | issue=9 | doi=10.1063/1.2975157 | last1=Lin | first1=Jian | last2=Ma | first2=Dongge }}</ref> or PCz.<ref>{{Cite journal|last1=Teo|first1=E. Y. H.|last2=Zhang|first2=C.|last3=Lim|first3=S. L.|last4=Kang|first4=E.|last5=Chan|first5=D. S. H.|last6=Zhu|first6=C.|date=May 2009|title=An Organic-Based Diode–Memory Device With Rectifying Property for Crossbar Memory Array Applications|journal=[[IEEE Electron Device Letters]]|volume=30|issue=5|pages=487–489|doi=10.1109/LED.2009.2017387|issn=0741-3106|bibcode=2009IEDL...30..487Y|s2cid=19858062 }}</ref> Organic WORM devices, considered organic memory, could be used as memory elements for low-power [[RFID]] tags.<ref>[http://www2.imec.be/be_en/press/imec-news/archive-2009/holst-centre-reports-major-step-towards-organic-rfid.html "Holst Centre reports major step towards organic RFID"]</ref>
+== See also ==
+* [[Append-only]]
 == Notes ==