Editing Backup (section)

===Storage media===
[[File:DVD, USB flash drive and external hard drive.jpg|thumb|right|From left to right, a [[DVD]] disc in plastic cover, a USB flash drive and an [[external hard drive]]]]
Regardless of the repository model that is used, the data has to be copied onto an archive file data storage medium. The medium used is also referred to as the type of backup destination.

====Magnetic tape====
[[Magnetic tape data storage|Magnetic tape]] was for a long time the most commonly used medium for bulk data storage, backup, archiving, and interchange. It was previously a less expensive option, but this is no longer the case for smaller amounts of data.<ref name=EngenioDiskToDiskVsTape>{{cite web  |date=9 December 2004  |access-date=26 May 2019
   |url=http://www.storagesearch.com/engenio-art2.html  |archive-url=https://web.archive.org/web/20050207082953/http://www.storagesearch.com/engenio-art2.html  |url-status=dead  |archive-date=7 February 2005  |title=Disk to Disk Backup versus Tape – War or Truce? |last1=Gardner |first1=Steve |at=Peaceful coexistence |publisher=Engenio
 }}</ref> Tape is a [[sequential access]] medium, so the rate of continuously writing or reading data can be very fast. While tape media itself has a low cost per space, [[tape drive]]s are typically dozens of times as expensive as [[hard disk drive]]s and [[optical drive]]s.

Many tape formats have been proprietary or specific to certain markets like mainframes or a particular brand of personal computer. By 2014 [[Linear Tape-Open#Market performance|LTO]] had become the primary tape technology.<ref name="SpectraLogicDigitalDataStorageOutlook2017">{{cite web |title=Digital Data Storage Outlook 2017 |url=https://spectralogic.com/wp-content/uploads/white-paper-digital-data-storage-outlook-2017-v3.pdf |website=Spectra |publisher=Spectra Logic |access-date=11 July 2018 |page=7(Solid-State), 10(Magnetic Disk), 14(Tape), 17(Optical) |year=2017}}</ref> The other remaining viable "super" format is the [[IBM 3592]] (also referred to as the TS11xx series). The [[StorageTek tape formats#T10000|Oracle StorageTek T10000]] was discontinued in 2016.<ref name="ForbesKeepingDataLongTime">{{cite web |author=Tom Coughlin  |title=Keeping Data for a Long Time |url=https://www.forbes.com/sites/tomcoughlin/2014/06/29/keeping-data-for-a-long-time/ |website=Forbes |access-date=19 April 2018 |date=29 June 2014 |at=para. Magnetic Tapes(popular formats, storage life), para. Hard Disk Drives(active archive), para. First consider flash memory in archiving(... may not have good media archive life)}}</ref>

====Hard disk====
The use of [[hard disk]] storage has increased over time as it has become progressively cheaper. Hard disks are usually easy to use, widely available, and can be accessed quickly.<ref name="SpectraLogicDigitalDataStorageOutlook2017" /> However, hard disk backups are [[Hard disk drive#Magnetic recording|close-tolerance mechanical devices]] and may be more easily damaged than tapes, especially while being transported.<ref name="PCWorldHardCoreDataPreservation">{{cite web |last1=Jacobi |first1=John L. |title=Hard-core data preservation: The best media and methods for archiving your data |url=https://www.pcworld.com/article/2984597/storage/hard-core-data-preservation-the-best-media-and-methods-for-archiving-your-data.html |website=PC World |access-date=19 April 2018 |date=29 February 2016 |at=sec. External Hard Drives(on the shelf, magnetic properties, mechanical stresses, vulnerable to shocks), Tape, Online storage}}</ref> In the mid-2000s, several drive manufacturers began to produce portable drives employing [[Hard disk drive failure#Unloading|ramp loading and accelerometer]] technology (sometimes termed a "shock sensor"),<ref name="HGSTRampLoadUnload">{{cite web |title=Ramp Load/Unload Technology in Hard Disk Drives |url=https://www.hgst.com/sites/default/files/resources/LoadUnload_white_paper_FINAL.pdf |website=HGST |publisher=Western Digital |access-date=29 June 2018 |page=3(sec. Enhanced Shock Tolerance) |date=November 2007}}</ref><ref name="ToshibaCanvio3.0PortableHDD">{{cite web |title=Toshiba Portable Hard Drive (Canvio® 3.0) |url=https://www.toshibadata.com.sg/Product-Canvio-Portable-Hard-Drive.aspx |website=Toshiba Data Dynamics Singapore |publisher=Toshiba Data Dynamics Pte Ltd |access-date=16 June 2018 |year=2018 |at=sec. Overview(Internal shock sensor and ramp loading technology)}}</ref> and by 2010 the industry average in drop tests for drives with that technology showed drives remaining intact and working after a 36-inch non-operating drop onto industrial carpeting.<ref name="IomegaDropShock">{{cite web |title=Iomega Drop Guard ™ Technology |url=https://www.doc-developpement-durable.org/file/Projets-informatiques/Drop%20Guard-disque-dur-tres-solide.pdf |website=Hard Drive Storage Solutions |publisher=Iomega Corp. |access-date=12 July 2018 |pages=2(What is Drop Shock Technology?, What is Drop Guard Technology? (... features special internal cushioning .... 40% above the industry average)), 3(*NOTE) |date=20 September 2010}}</ref> Some manufacturers also offer 'ruggedized' portable hard drives, which include a shock-absorbing case around the hard disk, and [[MIL-STD-810#Applicability to "ruggedized" consumer products|claim]] a range of higher drop specifications.<ref name="IomegaDropShock" /><ref name=PCMagBest>
{{cite web |author=John Burek
   |title=The Best Rugged Hard Drives and SSDs
   |url=https://www.pcmag.com/roundup/361072/the-best-rugged-hard-drives-and-ssds
   |website=[[PC Magazine]] |publisher=Ziff Davis |access-date=4 August 2018
   |at=What Exactly Makes a Drive Rugged?(When a drive is encased ... you're mostly at the mercy of the drive vendor to tell you the rated maximum drop distance for the drive) |date=15 May 2018}}</ref><ref name="WirecutterBestPortableHardDrive2017Don'tBuy">{{cite web
   |author=Justin Krajeski  |author2=Kimber Streams 
   |title=The Best Portable Hard Drive
   |url=http://thewirecutter.com/reviews/best-portable-hard-drive/#dont-buy-a-rugged-portable-hard-drive
   |work=[[The New York Times]] |access-date=4 August 2018
   |archive-url=https://web.archive.org/web/20170331161821/http://thewirecutter.com/reviews/best-portable-hard-drive/#dont-buy-a-rugged-portable-hard-drive  |url-status=dead  |archive-date=31 March 2017 |date=20 March 2017}}</ref> Over a period of years the stability of hard disk backups is shorter than that of tape backups.<ref name="ForbesKeepingDataLongTime" /><ref name="IronMountainBestLong-TermDataArchiveSolutions">{{cite web |title=Best Long-Term Data Archive Solutions |url=http://www.ironmountain.com/resources/general-articles/b/best-long-term-data-archive-solutions |website=Iron Mountain |publisher=Iron Mountain Inc. |access-date=19 April 2018 |year=2018 |at=sec. More Reliable(average mean time between failure ... rates, best practice for migrating data)}}</ref><ref name="PCWorldHardCoreDataPreservation" />

External hard disks can be connected via local interfaces like [[SCSI]], [[USB]], [[FireWire]], or [[eSATA]], or via longer-distance technologies like [[Ethernet]], [[iSCSI]], or [[Fibre Channel]]. Some disk-based backup systems, via [[Virtual tape library|Virtual Tape Libraries]] or otherwise, support data deduplication, which can reduce the amount of disk storage capacity consumed by daily and weekly backup data.<ref name="KissellTakeControlBackingUp">{{cite book |last1=Kissell |first1=Joe |title=Take Control of Backing Up Your Mac |date=2011 |publisher=TidBITS Publishing Inc. |location=Ithaca NY |isbn=978-1-61542-394-1 |page=41(Deduplication) |url=https://books.google.com/books?id=ANe3k_7bnAcC&q=retrospect+deduplication&pg=PT41 |access-date=17 September 2019}}</ref><ref>{{Cite web |url=http://www.dcig.com/2009/07/symantec-shows-backup-exec-a-l.html |title=Symantec Shows Backup Exec a Little Dedupe Love; Lays out Source Side Deduplication Roadmap – DCIG |website=DCIG |date=7 July 2009 |access-date=26 February 2016 |archive-url=https://web.archive.org/web/20160304212819/http://www.dcig.com/2009/07/symantec-shows-backup-exec-a-l.html |archive-date=4 March 2016 |url-status=live |df=dmy-all}}</ref><ref name="NetBackupDeduplicationGuide">{{cite web |title=Veritas NetBackup™ Deduplication Guide |url=https://www.veritas.com/content/support/en_US/doc/ka6j00000000ADEAA2 |website=Veritas |publisher=Veritas Technologies LLC |access-date=26 July 2018 |year=2016}}</ref>

====Optical storage====
[[File:Water running on CD-RW - label side.jpg|thumb|Optical discs are not vulnerable to water, making them likely to survive a flood disaster.]]
{{See also|Optical media preservation}}
[[Optical storage]] uses lasers to store and retrieve data. Recordable [[CD]]s, DVDs, and [[Blu-ray Disc]]s are commonly used with personal computers and are generally cheap. The capacities and speeds of these discs have typically been lower than hard disks or tapes. Advances in optical media may shrink that gap in the future.<ref name="WanOptical14">{{cite journal
   |title=Optical storage: An emerging option in long-term digital preservation
   |journal=Frontiers of Optoelectronics
   |author1=S. Wan |author2=Q. Cao |author3=C. Xie |volume=7 |issue=4 |pages=486–492 |year=2014
   |doi=10.1007/s12200-014-0442-2|s2cid=60816607
 }}</ref><ref>{{cite journal
|title=High-capacity optical long data memory based on enhanced Young's modulus in nanoplasmonic hybrid glass composites
|journal=Nature Communications
|author1=Q. Zhang |author2=Z. Xia |author3=Y.-B. Cheng |author4=M. Gu
|volume=9 |issue=1
|pages=1183 |year=2018 |doi=10.1038/s41467-018-03589-y|pmid=29568055
|bibcode=2018NatCo...9.1183Z
|pmc=5864957 }}</ref>

Potential future data losses caused by gradual [[disc rot|media degradation]] can be [[Predictive failure analysis|predicted]] by  [[optical disc#Surface error scanning|measuring the rate of correctable minor data errors]], of which consecutively too many increase the risk of uncorrectable sectors. Support for error scanning varies among [[optical drive]] vendors.<ref>{{cite web |last1=Bärwaldt |first1=Erik |title=Full Control » Linux Magazine |url=https://www.linux-magazine.com/Issues/2014/169/QPxTool |website=Linux Magazine |date=2014}}</ref>

Many optical disc formats are [[Write Once Read Many|WORM]] type, which makes them useful for archival purposes since the data cannot be changed in any way, including by user error and by malware such as [[ransomware]]. Moreover, optical discs are [[fault tolerance|not vulnerable]] to [[head crash]]es, magnetism, imminent water ingress or [[Voltage spike|power surge]]s; and, a fault of the drive typically just halts the spinning.

Optical media is [[modularity|modular]]; the storage controller is not tied to media itself like with hard drives or flash storage (→[[flash memory controller]]), allowing it to be removed and accessed through a different drive. However, recordable media may degrade earlier under long-term exposure to light.<ref>{{cite web |title=5. Conditions That Affect CDs and DVDs • CLIR |url=https://www.clir.org/pubs/reports/pub121/sec5/ |website=CLIR}}</ref>

Some optical storage systems allow for cataloged data backups without human contact with the discs, allowing for longer data integrity. A French study in 2008 indicated that the lifespan of typically-sold [[CD-R#Lifespan|CD-Rs]] was 2–10 years,<ref name=INA_CD-R_Study>{{cite web
   |url=http://www.ina.fr/video/3571726001/20-heures-emission-du-3-mars-2008.fr.html
   |title= Journal de 20 Heures |access-date=3 March 2008
   |at=approximately minute 30 of the TV news broadcast
   |work= Institut national de l'audiovisuel
   |author1=Gérard Poirier   |author2=Foued Berahou
   |date=3 March 2008}}</ref> but one manufacturer later estimated the longevity of its CD-Rs with a gold-sputtered layer to be as high as 100 years.<ref>{{cite web
   |url=http://delkin.com/i-5937134-archival-gold-cd-r-300-year-disc-binder-of-10-discs-with-scratch-armor-surface.html
   |title=Archival Gold CD-R "300 Year Disc" Binder of 10 Discs with Scratch Armor Surface
   |archive-date=27 September 2013 |archive-url=https://web.archive.org/web/20130927170900/http://delkin.com/i-5937134-archival-gold-cd-r-300-year-disc-binder-of-10-discs-with-scratch-armor-surface.html
   |website=Delkin Devices |publisher=Delkin Devices Inc.}}</ref> Sony's [[proprietary format|proprietary]] [[Optical Disc Archive]]<ref name="SpectraLogicDigitalDataStorageOutlook2017" /> can in 2016 reach a read rate of 250&nbsp;MB/s.<ref name="SonyOpticalDiscArchiveGen2">{{cite web |title=Optical Disc Archive Generation 2 |url=https://pro.sony/s3/cms-static-content/file/49/1237494482649.pdf |website=Optical Disc Archive |publisher=Sony |access-date=15 August 2019 |page=12(World’s First 8-Channel Optical Drive Unit) |date=April 2016}}</ref>

====Solid-state drive====
[[Solid-state drives]] (SSDs) use [[integrated circuit]] assemblies to store data. [[Flash memory]], [[thumb drive]]s, [[USB flash drive]]s, [[CompactFlash]], [[SmartMedia]], [[Memory Stick]]s, and [[Secure Digital card]] devices are relatively expensive for their low capacity, but convenient for backing up relatively low data volumes. A solid-state drive does not contain any movable parts, making it less susceptible to physical damage, and can have huge throughput of around 500&nbsp;Mbit/s up to 6&nbsp;Gbit/s. Available SSDs have become more capacious and cheaper.<ref>{{cite journal
   |title=Solid-State Drives (SSDs) |journal=Proceedings of the IEEE
   |author1=R. Micheloni |author2=P. Olivo
   |volume=105 |issue=9 |pages=1586–88 |year=2017
   |doi=10.1109/JPROC.2017.2727228 }}</ref><ref name=PCMagBest/> Flash memory backups are stable for fewer years than hard disk backups.<ref name="ForbesKeepingDataLongTime" />

====Remote backup service====
[[Remote backup service]]s or cloud backups involve service providers storing data offsite. This has been used to protect against events such as fires, floods, or earthquakes which could destroy locally stored backups.<ref name="DellRemoteBackup">{{cite web
   |url=https://www.emc.com/corporate/glossary/remote-backup.htm
   |title=Remote Backup |work=EMC Glossary |publisher=Dell, Inc
   |access-date=8 May 2018
   |quote=Effective remote backup requires that production data be regularly backed up to a location far enough away from the primary location so that both locations would not be affected by the same disruptive event.}}</ref> Cloud-based backup (through services like or similar to [[Google Drive]], and [[Microsoft OneDrive]]) provides a layer of data protection.<ref name="PCWorldHardCoreDataPreservation" /> However, the users must trust the provider to maintain the privacy and integrity of their data, with confidentiality enhanced by the use of [[encryption]]. Because speed and availability are limited by a user's online connection,<ref name="PCWorldHardCoreDataPreservation" /> users with large amounts of data may need to use cloud seeding and large-scale recovery.