NAS vs Backup Appliance (or LTO): Choosing a Backup Target in Malta

What does a backup target have to survive?

A backup target has to survive whatever destroys the live data. That can be a dead server, a deleted folder, ransomware run with an administrator’s password, or a fire in the building. A NAS, a purpose-built backup appliance and an LTO library each cover part of that list, so start from the event that would hurt your business most.

Modern ransomware looks for snapshots and backups and deletes them before encrypting anything, often with stolen admin credentials, as we describe in our high-availability and air-gapped backup case study. A backup target that any domain administrator can reach and wipe gives little protection against that.

Restore time comes next. If the accounts server fails on a Monday morning, does it have to be running again by lunch, or can it wait a day? Disk restores quickly; tape restores slowly. How long the copies must be kept is set by contracts and regulators, and our guide to LTO for compliance retention covers that side.

Is an immutable backup the same as an offline one?

No. An immutable backup cannot be changed or deleted for a set period, even by an administrator, but it still sits on a powered box on your network. An offline backup cannot be reached from the network at all. Someone who holds your admin password cannot delete an immutable copy, but can wait until its lock expires.

On a Synology NAS, immutable snapshots and the shared folders they belong to cannot be deleted during the protection period you set. DSM keeps up to 1,024 snapshots per shared folder, depending on the model (Synology Snapshot Replication specifications). Quantum DXi appliances offer Secure Snapshots with a set number of days before deletion; once snapshots are scheduled, the feature cannot be disabled globally (Quantum DXi9000 series user guide).

Synology’s ActiveProtect appliances add isolation on top. In its blog post on purpose-built backup appliances, Synology describes backup servers that are cut off from the network when nobody needs them, up to shutting the hardware down at set times. An LTO cartridge on a shelf is offline with no setting involved.

A 14-day lock does not help if the intrusion is found on day 20, so set the protection period from how long an attack could go unnoticed, and keep one copy offline as well.

When is a Synology NAS the right backup target?

Choose a Synology NAS as the backup target when you have a few servers and PCs and want fast restores from disk at the lowest cost. Someone in-house, or a partner, has to set up and watch the backup jobs. Run it as a dedicated backup box, with immutable snapshots switched on.

Our compliance-grade backup case study shows that setup for the professional services office mentioned above. We deployed a Synology RS822RP+, a 4-bay 1U rack NAS. The RP stands for a redundant, second power supply, so the unit keeps running if one supply fails.

Immutable WriteOnce snapshots protect the folders that need them, with retention mapped to the firm’s requirements. Data scrubbing runs at least quarterly to catch silent corruption, we tested restores at handover, and an Eaton UPS gives the NAS a clean shutdown in a power cut.

Synology’s Active Backup for Business is licence-free on the NAS and backs up PCs, servers and virtual machines. Hyper Backup then sends a copy to a second NAS or to Synology C2 cloud storage. The 4-bay RS822+ has been succeeded by the RS826+ and RS826RP+. The short-depth RS1226+ suits a wall cabinet in a branch, and the 16-bay RS2825RP+ adds redundant power for larger estates. Our guide to the Synology product range covers the rest of the line-up.

Customers with compliance duties or sensitive data usually choose SHR-2 or RAID 6 on the backup NAS, so two drives can fail without losing the volume. Whoever administers a NAS can usually change its backup settings, and a NAS that also serves files shares its risk with the file server. Keep the backup NAS for backup only, give it its own admin account with two-factor sign-in, and keep at least one copy somewhere it cannot reach.

When does a purpose-built backup appliance make more sense?

A purpose-built backup appliance is a backup server built only to hold backups. Its drives, deduplication, immutable copies and restore tools are supplied and supported as one unit. Pick one over a NAS when whole servers must come back quickly, when nobody in-house runs backups, or when an auditor wants evidence that backups cannot be altered.

Synology ActiveProtect DP series

Synology sizes its ActiveProtect DP series by a “suggested backup source”, from 5 TB on the DP320 tower to 83.5 TB on the 2U DP7400. The 1U DP5200 suggests 21.5 TB and the 2U ActiveProtect DP7200 56 TB. ActiveProtect includes the backup software, and Synology states that you do not need to buy multiple licences to use specific features. It deduplicates at the source and on the server (Synology ActiveProtect).

Restore is where an ActiveProtect appliance differs most from a NAS. A failed server can run as a virtual machine on the appliance itself while the hardware is repaired: Synology suggests two concurrent restored VMs on the DP5200 and four on the DP7200, more with added memory. A built-in sandbox lets you rehearse a disaster recovery without touching production. Synology’s blog post on purpose-built backup appliances adds that the people who run the servers cannot change the backup configuration, and that access can be limited to authorised IP addresses.

Quantum DXi for the backup software you already run

Quantum DXi is a target for your existing backup software, for a business that wants a faster, smaller place to write its backups. DXi deduplicates by up to 70:1 in Quantum’s field data, offers Secure Snapshots, and replicates to a second DXi, to tape or to the cloud.

actiData Ti-NAS RT Gen2, a NAS with an LTO drive inside

The actiData Ti-NAS RT Gen2 puts a six-bay RAID NAS (120 TB gross) and an LTO tape drive in one 2U chassis. Backups land on disk for fast restores, then copy to tape inside the box, so the tape copy adds no traffic to your network. It runs the backup software of your choice. A site that already has a NAS is better served by a separate drive from the actiData LTO range.

A backup appliance is still an online box in your building. Immutable copies on ActiveProtect survive a stolen password within the lock period, and DXi Secure Snapshots add a deletion lock. But a fire or flood in the server room takes the appliance with the servers, so it still needs a copy that leaves the building. ActiveProtect and DXi are meant for backup only, so they are bought in addition to the NAS that serves files.

When should backups go to an LTO tape library?

An LTO tape library is the backup target for a copy that must be physically offline, kept for years, or both. A cartridge out of the drive cannot be reached over the network, which makes tape the usual last copy behind a NAS or appliance.

A tape restore is bounded by drive speed and the number of drives. actiData rates its half-height LTO-9 drive at up to 300 MB/s native (actiData actiTape 1U Professional), about 1.1 TB an hour. Treat that as a ceiling. Archiware, which makes the P5 backup software, finds that real jobs fall short of the datasheet: an LTO-9 drive rated at 400 MB/s writes nearer 300 to 370 MB/s in good conditions, and around 250 MB/s when it reads from a NAS over 10 GbE (Archiware). Restoring 20 TB through one half-height drive therefore takes at least 18.5 hours, before any time to load and position cartridges. A library with several drives restores in parallel. The actiData Kodiak 3416 holds 40 cartridges and up to three drives in a 3U base module, 720 TB native with LTO-9. actiData rates the library at 3.2 TB an hour native, and it grows with expansion modules.

A new LTO-9 cartridge calibrates itself the first time it is loaded, typically for 35 to 52 minutes and up to two hours (Quantum LTO-9 FAQ). Load and calibrate new media before the first backup window.

Work with native speeds and capacities, not the compressed figures on the box. Photos, video, ZIP archives and encrypted files barely compress, so the 2.5:1 ratio behind the compressed numbers rarely appears in a real backup.

What slows an LTO drive down?

An LTO drive writes only as fast as data reaches it. When the feed slows, the drive slows the tape to match, but only down to a floor: about 180 MB/s native for LTO-9 and 112 MB/s for LTO-8, by IBM’s figures as quoted by Archiware. Below that floor the tape stops, winds back a little and starts again each time the buffer refills, which tape people call shoe-shining. The backup still finishes, but slowly, and the stop-start wears the drive heads and the cartridges faster.

A NAS on a 1 GbE link delivers about 100 to 110 MB/s in practice, well under the LTO-9 floor. So we feed tape from local disk or over 10 GbE: the backup lands on the NAS or appliance first, and the tape copy is made from there. The actiData Ti-NAS RT Gen2 does that inside one box.

Many small files slow a job at the source rather than on the tape, because the backup server has to open and read each file in turn. If the tapes are written in LTFS, so that any computer can open them, bundle small files into one archive first; LTFS suits large files such as video originals and image sets.

Restores are often slower than backups, and the tape is rarely the reason. The disk you restore to sets the pace: a RAID 6 volume writes more slowly than it reads, and writing back hundreds of thousands of small files hits the disks’ limit. Backups that interleave several jobs on one tape save time at night and cost time at restore. Test a restore to the real destination, not only a backup.

LTO generations are only partly compatible. An LTO-9 drive reads and writes LTO-8 and LTO-9 only, and an LTO-10 drive reads and writes LTO-10 only (LTO Program). Moving to a new generation later means keeping a drive for the old tapes or migrating the archive, and we offer tape archive migration onto disk.

Restoring one deleted file from tape means loading a cartridge and winding to the data, which takes far longer than fetching it from disk. A library has moving parts that need servicing, and a tape set that has never been test-restored has not been proven. For the choice between a standalone drive, an autoloader and a library, see our LTO buyer’s guide.

How do a NAS, a backup appliance and an LTO library compare?

A NAS gives the fastest restores for the money, an appliance brings whole servers back with the least work, and a tape library is the only one of the three that is offline by default. Where each falls short decides how you combine them.

When is a simpler backup target enough?

A simpler backup target may be enough for an office with a few terabytes and a handful of PCs. A backup-only Synology NAS running Active Backup for Business can cover it, as long as one copy also leaves the building. The smallest ActiveProtect appliance, the DP320, has a suggested backup source of 5 TB, so for a small office the question is whether its restore features are worth a second box.

A standalone actiData actiTape drive is enough for tape when one server’s backup fits on a single cartridge and someone reliably changes the tape.

No backup target protects a business on its own. A single box in the same building as the servers fails with the building, and a backup that has never been restored is untested, so plan a second copy and a restore test whichever target you choose.

Does the backup target need a UPS?

Yes. A backup target that loses power mid-job leaves a half-written backup, and a NAS that drops with its volumes mounted may need a consistency check before it can be trusted. An Eaton UPS gives the target enough minutes to finish or stop cleanly and tells it when to shut down.

A Synology NAS can be set to shut down safely when a connected Eaton UPS reports low battery. To shut several boxes down in order, the UPS needs the Eaton Network-M3 card, included on Eaton 5PX Gen2 Netpack models and optional on the 9SX Gen2. Dual power supplies, as on the RS822RP+, the Ti-NAS RT Gen2 and the Kodiak 3416, cover a failed supply inside the box and do nothing for a mains cut. Our UPS sizing guide works out the runtime.

How Sirap sets up a backup target in Malta

We size a backup target from the restore you need: how much data, how fast it must come back, and how long each version must be kept. The daily change rate matters too, because it sets how much new data each backup writes and, with retention, how much capacity the target needs. We quote from your data volume and restore time.

We then choose the NAS, appliance or library, and usually a second target for the copy that leaves the building. That copy might be Hyper Backup to a second NAS that we manage, Synology C2 cloud storage, or LTO cartridges in rotation.

At installation we set the RAID level, the immutable snapshot periods and the backup admin accounts, connect the UPS shutdown, check that the tape drive is fed fast enough to keep streaming, and test a restore at handover. On Synology and Eaton equipment, a SirapCare service contract extends the warranty to five years and adds preventive maintenance, priority response and a loan unit in an emergency.

Before you buy anything, time a full restore of your largest server from the backups you have today. That number tells you which target you need.