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Evaluation process: How do you plan to evaluate each VTL solution -- from online product literature, by talking with the vendor, or by obtaining a demo unit and trying it out? Devise a scoring and ranking system to apply to each solution you evaluate. |
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Capacity requirements: What are your overall capacity requirements? How long will you keep data on the VTL before moving it to physical tape or deleting (overwriting) it? Can you achieve your capacity requirements by using data compression on a smaller capacity device? The questions may narrow your choices down to just a few VTL options almost immediately. |
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Backup software support: Does your backup software application support the library, tape drives, and cartridges emulated by the VTL? Is your backup software certified to work with the VTL? Does your backup software support copying of virtual tapes to physical tape (commonly referred to as "tape-to-tape copy")? Even though VTLs are meant to seamlessly plug into your backup environment, this largely depends on your backup software application. |
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Hardware or software VTL: Do you want a hardware VTL or a software VTL solution that you can install on commodity hardware? In many cases, when selecting a software-enabled VTL, you must also manage other types of storage (such as Windows File Systems) on the same device which might make storage management more complex when compared to a dedicated VTL appliance. You should also determine whether you prefer to have one vendor support the VTL or are willing to work with several vendors. |
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Network and backup device bandwidth: How many servers will you be backing up to the VTL? Can you achieve sufficient network and backup performance when streaming multiple servers to the VTL? A VTL solution such as the HP VLS1000i can backup up to 12 servers, but maintains optimal backup speeds while backing up to 3-5 servers simultaneously. |
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Support SLA (service level agreement): What kind of support does the vendor offer: web, phone, chat, or a combination? Find out whether the vendor offers a support SLA, their guaranteed response times for support, and whether they offer onsite support or remote support only. |
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Redundancy and spare parts replacement: What kind of redundancy does the VTL offer? Many VTL redundancy features range from RAID 5 all the way to redundant VTLs, controllers, enclosures, and Fibre Channel HBAs (host bus adaptors). When something does fail, how quickly can the vendor ship a replacement, such as a replacement hard drive? |
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Management interface: Which management interfaces are available for the VTL - web (or browser-based), application-based, or command-line? Does the VTL support an out-of-band connection method, such as a serial port, in case the VTL crashes and requires a reboot? |
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Expandability: What is the maximum storage capacity of the VTL and how can it be expanded in the future? Will you need to scale-up (replace hard drives with higher capacity hard drives in the future) or scale-out (add additional storage components to get needed capacity expansion in the future), or both? There may be tradeoffs to consider such as price versus expandability. Typically, lower priced VTLs can be scaled-up, but can not support scale-out features. |
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Connectivity: Does the VTL support Fibre Channel, iSCSI, or both? Make sure the VTL connectivity is compatible with your network or SAN. In the case of Fibre Channel, find out if the Fibre Channel HBA has single or multi-path support. |
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Environmental: Find out how much rack space the VTL consumes and whether it fits in your current rack system, and determine the VTL's power requirements. |
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Budget: What percentage of your IT budget are you willing to devote to your VTL solution and its maintenance? Is there a set amount already mandated by senior IT management? How quickly can you push your chosen solution through the approval process? This can effect your overall delivery date. |
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