I have heard that large hardisk >= 1TB are not recommended on the server because they can cause synching issues if one fails + their chances of failure is greater over a longer period of time as the hard disk get fuller. Is that assumption correct?

I am specifically asking about RAID 1 configuration (hard disk mirroring) where the same data is written to two hard disks. Is a way I am asking is 300GB better suited than a 2TB from stability and maintenance point of view?

Extra Info

We will using it as our server for website and the databases. Our database size is only 1GB rights and will likely not sky rocket any time soon. We are not using it as file server and no body has access to this server.

My argument for large hard drive is, we will be running daily backup so we can just store it on the same hard drive and not worry about an external hard drive. Also if if there is ever a need for more space, we will have it without any problem.

My college view is external USB drive is much better for daily backup and does not fail easily + large hard drive can cause issues after 6 months or so when hard disk become fuller.

So what is recommended size of hard disk for server so the server remains stable and fast?

  • 3
    Please don't put backups on the same disk as your database, that's like keeping your spare key on the same key-ring as your main key. You're looking to host a small website and purchase a server to host it yourself? While I'm not entirely opposed to the idea, you might be a better candidate for a virtual machine... Try looking into Azure or AWS. – Reaces Jul 30 '15 at 9:23
  • @Reaces our server hosts a local site that is served across our organization only, some 400 employees but only about 20 uses the database – Savage Garden Jul 30 '15 at 9:27

What you have probably heard is that for RAID5 configurations using large disks problems can arise under some circumstances. These problems are not an issue for RAID 1 as the rebuild I/O is less than that of RAID5.

What's the recommended size? - that which will do the job with some elbow room for expansion.

we will be running daily backup so we can just store it on the same hard drive and not worry

Don't do that it's a terrible idea. RAID is for availability not backups. People who rely on RAID as their sole backup regularly lose all their data. You should have some external and preferably offsite backup.

  • Aside from the advise that I shouldn't be saving backup on the same machine, I would really like someone actually comment on hard disk size as well, if it can be an issue at all.I think he was referring to RAID 1 configuration because after failure of one device, when you connect a new one, the synching can take days! – Savage Garden Jul 30 '15 at 9:36
  • No one will make the decision for you, only you know what's right for you and your data and your business. We don't do capacity planning Q&A because there are too many variables and most people are unaware of their real requirements. – Iain Jul 30 '15 at 9:45
  • 2
    That is exactly what Iain addresses in the very answer you're commenting on. If a 1-3TB RAID-1 resync takes days, you're thrashing your HDDs to the point of insensibility; it should take 6-12 hours at the most. RAID-5 resyncs take much longer because of the read-recalculate-write cycle, and the consequent requirement to read everything on every remaining HDD in the array. That said, if you have enough bays to provide the payload you need with fully-mirrored smaller devices (300-600GB), your performance will definitely benefit from the increased number of spindles. – MadHatter Jul 30 '15 at 9:45
  • @MadHatterRAID-0s don't resync ;) – Iain Jul 30 '15 at 9:48
  • @Iain d'oh - I'm a moron. Fixed, thanks. And good morning to you! – MadHatter Jul 30 '15 at 9:49

it is not good idea to store your backup data on the same disk, because if the disk fails someday, you will lost the data. I will suggest you to keep your backups on the separate disk, cloud or tape solution. This way you will prevent lost important data.

As for the disk, I will suggest you to calculate how much disk space you will need with eventual growth of the data and buy something will meet this requirements. There is no point to get 2TB disk, if you plan to use around 500GB and you expect growing around 100-200GB in following year.


Why do you want to put one pair of huge disks in there, when you have a server running a database?

If you want to look at performance, try putting your database on different disks than your OS / web application. Databases are often bottle-necked on I/O.
In stead of purchasing 2x 2TB disks, you could buy 2x 320GB disks for the OS / web app, and 2x 128GB SSD for the database.

And I don't think it needs much repeating but backups are important! Don't put them on the same disk as your database etc.

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