# 1 or 2 harddrives **URL:** \ **Category:** Factual Questions\ **Created:** [August 15, 2009, 7:52pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556 "2009-08-15T19:52:30Z")\ **Posts on this page:** 20\ **Page:** 1
**Author:** ![NadaHappyCamper](https://avatars.discourse-cdn.com/v4/letter/n/278dde/32.png) [@NadaHappyCamper](https://boards.straightdope.com/u/NadaHappyCamper)\ **Post date:** [August 15, 2009, 7:52pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/1 "2009-08-15T19:52:30Z")
I am contemplateing aquireing a new computer, and I see some that have two hard drives. Is there a benefit to having a second hard drive? Is there an anti- benefit to having a second drive? I suppose one drive could be used for operating a home based office, while a another could be used for gaming and entertainment, thats my thinking anywho. What are your thoughts fellow Dopers? ``` Nadahappycamper ``` ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [August 15, 2009, 7:55pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/2 "2009-08-15T19:55:50Z")
The best configuration for the speed of a PC is to have a fast hard, small (but expensive) hard drive running the OS and applications (like a velociraptor or an SSD drive) and a big slower drive to hold data files that don’t need to be fast. But I’m assuming your system simply has 2 identical drives. There can be some benefits - you can easily back up data across the two drives in case one fails. You could stick your OS and swap files on one drive and applications on the other drive, allowing them both to be used simultaneously, increasing the total data rate available. There’s not really any downside. ---
**Author:** ![DWMarch](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/dwmarch/32/1010_2.png) [@DWMarch](https://boards.straightdope.com/u/DWMarch)\ **Post date:** [August 15, 2009, 7:57pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/3 "2009-08-15T19:57:40Z")
I have two drives in my computer right now and it’s how I prefer things. The smaller C: is the drive Windows rests on. The big D: drive is labeled “BACKUP” and holds anything/everything I don’t want to lose if I ever have to reformat or if other disaster strikes. ---
**Author:** ![ftg](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ftg/32/2801_2.png) [@ftg](https://boards.straightdope.com/u/ftg)\ **Post date:** [August 15, 2009, 8:06pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/4 "2009-08-15T20:06:24Z")
Putting the swap file on its own HD was once a standard practice. With huge HD sizes now, you’d of course want to put something else on that drive. ---
**Author:** ![Fake\_Tales\_of\_San\_Francisco](https://avatars.discourse-cdn.com/v4/letter/f/8491ac/32.png) [@Fake\_Tales\_of\_San\_Francisco](https://boards.straightdope.com/u/Fake_Tales_of_San_Francisco)\ **Post date:** [August 15, 2009, 8:06pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/5 "2009-08-15T20:06:31Z")
I don’t know if it’s entirely relevant, but many of the computers you’ll see in the shops don’t actually have 2 hard drives, the single drive is simply partitioned. I think the purpose is to separate Windows from the rest of your data in case anything happens. In my experience, I haven’t found having a partition entirely useful and prefer an external drive to back up important data. ---
**Author:** ![drachillix](https://avatars.discourse-cdn.com/v4/letter/d/48db29/32.png) [@drachillix](https://boards.straightdope.com/u/drachillix)\ **Post date:** [August 15, 2009, 8:44pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/6 "2009-08-15T20:44:16Z")
> [@NadaHappyCamper](#): > > I am contemplateing aquireing a new computer, and I see some that have two hard drives. Is there a benefit to having a second hard drive? Is there an anti- benefit to having a second drive? I suppose one drive could be used for operating a home based office, while a another could be used for gaming and entertainment, thats my thinking anywho. What are your thoughts fellow Dopers? > > ``` > Nadahappycamper > > ``` One of the other options you may run into with a dual drive system is called RAID > **[RAID](https://en.wikipedia.org/wiki/RAID)** > > RAID is an orchestrated approach to computer data storage in which data is written to more than one secondary storage device. Instead of storing all data in a single hard disk drive or solid-state drive, RAID coordinates two or more such devices into a disk array. When the computer writes data to secondary storage, the RAID system distributes the data across the array. There are several possible ways of doing this, and those various configurations are called RAID levels. > RAID levels are distingu... The most popular manifestation there is called RAID-1 (mirror) > [@](#): > > Mirrored set without parity’ or ‘Mirroring’. Provides fault tolerance from disk errors and failure of all but one of the drives. Increased read performance occurs when using a multi-threaded operating system that supports split seeks, as well as a very small performance reduction when writing. Array continues to operate so long as at least one drive is functioning. Using RAID 1 with a separate controller for each disk is sometimes called duplexing. In non geek, this means the hard drives are always identical, if one fails, your computer still runs, and all your data is still there. Replace dead drive, it (mostly) automatically rebuilds the mirroring. This is a type of backup on the fly against hardware issues. This will not save you from a virus or software problems, but it will keep your data intact if a hard drive dies. ---
**Author:** ![ZipperJJ](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/zipperjj/32/211_2.png) [@ZipperJJ](https://boards.straightdope.com/u/ZipperJJ)\ **Post date:** [August 16, 2009, 3:49am UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/7 "2009-08-16T03:49:20Z")
I had to fix a computer last month that had a dying hard drive. I opened it up to find it had a second, identical 120GB un-formatted HDD inside. It was like opening up a kidney transplant recipient and finding an extra working kidney hiding behind the spleen. Score! You could always keep the second hard drive for a surprise 🙂 ---
**Author:** ![Bad\_Astronaut](https://avatars.discourse-cdn.com/v4/letter/b/e19adc/32.png) [@Bad\_Astronaut](https://boards.straightdope.com/u/Bad_Astronaut)\ **Post date:** [August 16, 2009, 7:14am UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/8 "2009-08-16T07:14:45Z")
There is one potential downside - two hard drives are noisier than one. Of course if you have a run-of-the-mill PC the hard drive noise will be insignificant compared to the vaccum-cleaner like noise from the fans. However, for people interested in quiet (or silent) computers, everything other than the hard drive is surprisingly easy to silence. In my PC I have one hard drive mounted in an elastic suspension system so as not to transmit as much vibration to the case and it’s by far the loudest component. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [August 16, 2009, 12:00pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/9 "2009-08-16T12:00:17Z")
One thing to consider is two hard drives consume more power than one. ---
**Author:** ![SenorBeef](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/senorbeef/32/2220_2.png) [@SenorBeef](https://boards.straightdope.com/u/SenorBeef)\ **Post date:** [August 16, 2009, 12:07pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/10 "2009-08-16T12:07:47Z")
The power usage by hard drives is very small, IIRC less than 10 watts. ---
**Author:** ![asterion](https://avatars.discourse-cdn.com/v4/letter/a/4da419/32.png) [@asterion](https://boards.straightdope.com/u/asterion)\ **Post date:** [August 16, 2009, 12:08pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/11 "2009-08-16T12:08:43Z")
I am currently running 4 hard drives in my desktop. The case actually has a place for an 80 mm fan just for the hard drive rack. Now, I am doing it somewhat wrong in that the OS is on the smallest but oldest and slowest hard drive. The major problem is that I think I’m out of SATA spots on my motherboard (the other three hard drives and the DVD burner are all SATA) while that little 40 gig drive is using EIDE along with the DVD-ROM drive, the CD-RW, and the Zip drive. This is not the greatest solution, but something that just evolved as I upgraded this computer. When I finally build myself a new one with the latest hardware (I’m 4 years behind on the CPU, am still using AGP instead of PCI-E for video, and so on) I’ll probably just get two new drives, a lightning-fast 80 gig or so for the OS and a 2 TB monster for everything else and partition it however I want. I bought two identical 320-gig drives with the intention of making a RAID-1. I eventually gave up on that because every time the computer was shut down improperly it spent the next two hours (I really think it was about this long) rebuilding the array before loading the OS. So, my setup is: 1. A 40-gig Maxtor hard drive from about 2001 using EIDE. Slow data transfer, slow read/write, slow access, small cache. I could easily upgrade it for under $50 if I’m happy with 7200 rpm, under $200 if I decided to go crazy and go to 15,000 rpm. 2. A 160-gig Western Digital using SATA. This is where, as a general rule, all programs are installed. Doing this helps whenever I have to reinstall the OS and then all the software since generally saved games and such don’t get overwritten when the program is reinstalled. Plus, it’s all in one place so I don’t have to go looking for an obscure program I need once a year or so. 3. A 320-gig Western Digital using SATA. This one is the big data holder. It’s got my music, movies, documents, disc images, and other things. 4. A 320-gig Wester Digital using SATA. This one is pretty much empty. Right now, it’s got the backup of my data from my laptop, my reinstall kit (just all the programs and drivers I need to get the computer up and running quickly after a format and reinstall), and is used for moving files across the network. This isn’t the best solution by any means. When I build a new one I’ll probably just go with one small but superfast drive and a 2 TB or so monster that I’ll partition. ---
**Author:** ![Kinthalis](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/kinthalis/32/16084_2.png) [@Kinthalis](https://boards.straightdope.com/u/Kinthalis)\ **Post date:** [August 16, 2009, 1:35pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/12 "2009-08-16T13:35:16Z")
RAID is the way to go for multi-drive systems. For a standard PC my recommendaiton matches **drachillix’s**. RAID 1 will mirror your drives. This essentially\* makes it impossible for you to loose your precious data. Not only that, but read speeds will increase, making the loading of programs and data snappier. Write speeds take a small hit, but usually it’s nothing you will notice much. - - IMPORTANT: RAID 1 will not protect you from things like mistakenly deleting your files, a system failure that affects BOTH drives at the same time, or obviously, things like fire and theft. It’s always a good idea to have another remote backup of important data elsewhere. ---
**Author:** ![SlickRoenick](https://avatars.discourse-cdn.com/v4/letter/s/e68b1a/32.png) [@SlickRoenick](https://boards.straightdope.com/u/SlickRoenick)\ **Post date:** [August 16, 2009, 2:01pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/13 "2009-08-16T14:01:11Z")
> [@DWMarch](#): > > The big D: drive is labeled “BACKUP” and holds anything/everything I don’t want to lose if I ever have to reformat or if other disaster strikes. A disaster can still wipe out your D drive. “Backup” usually means “2nd copy” ---
**Author:** ![Sunspace](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/sunspace/32/1250_2.png) [@Sunspace](https://boards.straightdope.com/u/Sunspace)\ **Post date:** [August 16, 2009, 2:49pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/14 "2009-08-16T14:49:50Z")
Another reason for two hard drives for your data is if you are dealing with large amounts of data, like video. You read from one drive, process the data, and write to the other drive. This works best if your OS and programs are on yet another drive. ---
**Author:** ![Harmonious\_Discord](https://avatars.discourse-cdn.com/v4/letter/h/74df32/32.png) [@Harmonious\_Discord](https://boards.straightdope.com/u/Harmonious_Discord)\ **Post date:** [August 16, 2009, 3:20pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/15 "2009-08-16T15:20:41Z")
> [@SenorBeef](#): > > The power usage by hard drives is very small, IIRC less than 10 watts. I knew someone would say that. It’s still less power consumed and it adds up. Stick with an external drive for back ups you only run when needed. ---
**Author:** ![Musicat](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/musicat/32/20189_2.png) [@Musicat](https://boards.straightdope.com/u/Musicat)\ **Post date:** [August 16, 2009, 3:35pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/16 "2009-08-16T15:35:25Z")
There are many operations where two drives (not two partitions on one drive) provide a speed improvement. A simple copy operation with one drive means the head moves to the source, copies a data slice to RAM, moves to the destination and copies from RAM to the disk, then updates the destination directory. That’s a lot of head movement if it has to be performed all on one drive. In contrast, with two drives, the head doesn’t need to move as much (assuming a defragged drive and contiguous files) from one source block to another, and the destination head moves less, too. Since head movements are the slowest part of disk reading/writing, it can make a difference. ---
**Author:** ![GusNSpot](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/gusnspot/32/436_2.png) [@GusNSpot](https://boards.straightdope.com/u/GusNSpot)\ **Post date:** [August 16, 2009, 5:36pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/17 "2009-08-16T17:36:09Z")
I agree and disagree with everything said!!! I gave up giving advice because everyone’s needs, conditions, $$$$, willingness to do this or that, etc., is all so different. What are the biggest dangers your particular situation has? What is important to you? $$$$ availability? And on and on… Just do something… In this day and age, I do not have much Sympathy or Empathy for those that loose everything because of a lack of taking even the most basic steps at protection of their important data. _::: And get off of my LAWN !!! ::::_ ---
**Author:** ![LSLGuy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lslguy/32/5813_2.png) [@LSLGuy](https://boards.straightdope.com/u/LSLGuy)\ **Post date:** [August 16, 2009, 6:43pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/18 "2009-08-16T18:43:59Z")
Are you sure you don’t mean ::: And get off of my **LAN**!!! :::: ---
**Author:** ![Superfluous\_Parentheses](https://avatars.discourse-cdn.com/v4/letter/s/8edcca/32.png) [@Superfluous\_Parentheses](https://boards.straightdope.com/u/Superfluous_Parentheses)\ **Post date:** [August 16, 2009, 6:55pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/19 "2009-08-16T18:55:13Z")
Using 2 (or more) drives you can spread out read/writes over multiple drives, which can speed up operations, or you can mirror data so you’ve got a hot copy ready when one drive fails. If you use more than 2 drives, you can have both. Note that pure striping (that is, spreading data over multiple drives without duplicating) will **increase** the chances of your data getting lost, assuming every drive has the same chance of failing. Once you get into largish arrays (say, 24 drives or more) you **will** get drive failures fairly often. ---
**Author:** ![Ruminator](https://avatars.discourse-cdn.com/v4/letter/r/b9bd4f/32.png) [@Ruminator](https://boards.straightdope.com/u/Ruminator)\ **Post date:** [August 16, 2009, 8:11pm UTC](https://boards.straightdope.com/t/1-or-2-harddrives/506556/20 "2009-08-16T20:11:24Z")
> [@NadaHappyCamper](#): > > I suppose one drive could be used for operating a home based office, while a another could be used for gaming and entertainment, thats my thinking anywho. Don’t think of the drives as “work” vs “home”. Instead, think of the separation as “Windows” vs “my data”. The first drive as C: drive that holds the operating system (Windows). The 2nd drive holds “data” such documents, photos, etc. I respectfully disagree with the others and don’t recommend messing around with RAID unless it’s an external drive enclosure (such as NAS) with built-in RAID. [Next page](https://boards.straightdope.com/t/1-or-2-harddrives/506556.md?page=2)