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Swap files and partitions on 4 disk RAID 0 array

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March 22, 2009 9:22:01 AM

Dear All,

I have a few questions regarding a RAID array:
- What packet size should I be using for general gaming / media tasks?
- Where should I place my Windows swap file?
- Should it be on the RAID or the 250Gb spindle?
- Should I create partitions - does this improve performance?

I run the following system:
- Vista Ultimate 32bit - upgrade to 64bit planned
- Q6600 B3 @ 2.4GHz
- 4x 1Gb Geil Black Dragon PC8500
- 4x Spinpoint F1 500Gb (RAID 0) - currently blank
- 1x 7200.10 250Gb
- ATi 4870

I intend to use the RAID for all my data and back up to an external system or the 250Gb HDD.

I understand that there is a greater probability of one disk failing in RAID and taking all the data with it. In 15 years of messing with computers I've only ever had one disk actually fail - they generally get upgraded before that point!!

It would be great to know your thoughts.

Many Thanks

Jeremy

March 22, 2009 2:28:19 PM

If you can, put the swap/page file on a different hard disk than the OS... I don't believe partitioning really helps your performance too much but I'd not put all my space in the one partition where the OS sits ...that's just me. I might give Windows 100GB in RAID 0, then mirror or some other flavor of RAID the rest. Again, I'd not put the page file on the same drive/partition as the OS if I had the option.
March 22, 2009 3:22:10 PM

Just to push you a little more why would you partition the OS away from the rest of the data?

Any thoughts on my other questions?

Thanks

Jeremy
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March 22, 2009 8:11:55 PM

That's a good question. I've always been of the thought that when I have the choice I like to keep my data away from the OS. That way if the OS goes south and I've got to rebuild it I don't have to worry about my data being on the same partition/drive.

...of course you have to have a good backup strategy, no matter what, but just for neatness sake and that outlined above, I like to keep my data on a seperate partition/drive than the OS(')
March 22, 2009 8:36:35 PM

Brilliant, thanks halcyon.

Seems like a good plan. Would it be worth partitioning my other HDD for the swap file as well? Data in one partition, another one (20Gb?) for the swap?

What do you think about packet size?

Thanks
Jeremy
March 22, 2009 8:48:11 PM

Well, you certainly don't need too much space for your swap file. If your swafile is going to be ...oh... 2GB, then a 3GB partition for it is more than enough, IMO. TBH, I think you could put your swap file on the same drive as your data. Hopefully, you've got enough RAM so that your rig won't spend a lot of time in the swap file. Now, if you really need to optimize the swap file for performance because you know you're short on RAM and Windows will need to rely on it...then, you may want to put it on a RAID0 array. ...but with RAM so cheap you shouldn't really need to think to much about a swap file.
March 22, 2009 9:00:50 PM

I've got 4Gb of RAM installed, I can't up it easily as it is 4x1Gb sticks.

Is there a way to tell if the system is using more RAM than available and then making use of the swap file?

Jeremy
March 22, 2009 9:35:10 PM

Well, right now you've got Vista 32bit so with 4GB you've got more RAM than the OS can actually see. You can minimize your swap file...or just leave it on automatic. With 4GB and Vista32 its as good as Vista32 is gonna get...but I think you'd notice that Vista64 is faster (at least it is in my experience).
March 23, 2009 8:02:18 AM

I'm currently running Vista 32bit, but I'm heading to 64bit next week - at that point I will get all my RAM. Does that make a difference in terms of swap file?

Do I want to minimise it, attempt to get the computer to use RAM first, or leave it large to avoid lack of RAM issues?

Jeremy
March 23, 2009 9:59:50 AM

I'd say with 4GB of RAM and Vista64, let Windows manage the swapfile still. ...if you ever want to go to >4GB then you can start to reduce the swap file. I.E., with 8GB you could set the swapfile to 0mb and VISTA would still be more than happy, IME.
March 23, 2009 10:28:25 AM

Ok, thanks Halcyon.

Do you have any info about packet sizes for the RAID array. Whether I should be using 8k, 16k or 128k etc.

Jeremy
March 23, 2009 11:06:12 AM

For RAID0 128K is common, for RAID1 64K is common...IME (gotta add that :p  )
March 23, 2009 11:32:38 AM

That's excellent, I've already set it up with 128K.

Jeremy
March 24, 2009 8:40:36 PM

A couple of points;

1. Disk use partitioning - A lot of people like having the OS and the Data on seperate disks (there are ongoing disputes over whether the regular applications go on the OS disk, the Data disk or a third one - I vote for the OS one). Basically, the purpose is twofold: a. It allows you to use a relatively small but fast disk for the time critical stuff, which is mainly the software, while the data can go on a big but not so fast disk. b. It makes backups easier on the assumption that you can always re-install the OS and applications but the data is gone for good if it gets lost. This last one is a little dubious because of the way Windows stores setup information in the Registry and all sorts of (undocumented) other places.

2. If you do go with the small, fast disk for OS and Applications approach, the page file should be on that disk simply because it is fast UNLESS it is an SSD... you don't want anything that gets written to frequently on an SSD if you can avoid it.

3. The official pagefile advice is garbage. Basically, the advice is that you should have twice as much pagefile as real memory. In practice, it is almost the exact opposite... on a 32bit OS subtract your real memory from 4GB and the answer is what your pagefile should be. On a 64bit OS, I suspect that using 8GB as the base is probably reasonable unless you know you need more.

4. ALWAYS use a fixed pagefile size (even if it is zero). Otherwise, Windows will gradually increase the size as needed and it will be a fragmentation nightmare. If you use a fixed size (same minimum and maximum) the file gets created once and stays in a single chunk.
March 24, 2009 9:17:13 PM

Thanks for the info Siggy, really helpful.

In terms of my set up, I have a large RAID which will be faster than the single 250Gb disk.

Which suggests that I would place all my time-critical stuff onto the large RAID - OS + programs. But given that I would also like to get at my data quickly too, could I not put all of it onto the RAID and then make sure to backup well? Or is there some more subtle problem with this approach?

I would like an SSD for my OS - but not if it costs me £400!!

Currently I'm on a 32bit OS with 4Gb of RAM and a 5.4Gb page file? Should I be reducing this?

Jeremy
a c 352 G Storage
March 24, 2009 9:51:27 PM

Additional rational on partitioning. With a large hard drive it is best to partition it. Generally your first partition is for OS and programs - Keep it small, BUT big enougth for future programs. This keeps operating system/program files on the outer edge of the platers where angular velocity is highest. Fragmentation is reduced by seperating Data (More frequency of change/additions) from OS/Programs. As Siggy99 stated a fixed Swap file has advantage, Perrsonally I setup a small logical drive for it - Hate having it stuck in the middle of other junk - Just me no real advantage.
Also BU's are generally easier, Just BU drive X
March 24, 2009 10:02:23 PM

"Small, but big enough for programs" - a how long is a piece of string statement if ever I saw one!!
With Vista (20Gb?), multiple games (8Gb each), large Adobe programs list (15Gb), Solid Works and AutoCad I'm probably looking 200-300Gb? Is that reasonable?

Do I then create a seperate partition, presumably after the OS section for the swap file? Maybe 10Gb?

Then leave the rest for data? Possibly add another partition for a Linux OS as well, or would that go with Vista?

Thanks for the help RetiredChief - good info. Although I'm a bit confused about BU's?
a c 352 G Storage
March 25, 2009 2:48:25 AM

For "string" info. I have 2 pairs of HDD's in raid0. 1 Pair has Vista, the other pair XP
Drive 0:
C: Vista + Programs – 60 Gigs, using 37 Gigs
D: Data1 540 Gig for Vista & XP data/files
Drive 1
E: XP and Programs - 45 Gig, using 25 Gigs
F: Swap file – 10 Gigs
G: Data2, Movies/pictures ( again shared vista/XP)

THE only thing you have to remember is Drive letters can change, if I boot Vista then Vista is C: - But if I boot XP XP becomes C: and the other drive letters change. I use names instead of letters so not to confusing.

4 500 gig = 2Terabytes, so ya 10%= 200 Gigs. For Operating system + programs High but OK(160 Gig usable - remember always leave about 10 -> 20 % of a HDD free.)

Don't really game, but do use schematic capture/drawing package and will be loading an o'scope (WaveStar for digital o'scope) program

Ref Backups (BU). I only Back-up my data/files that I create. They all reside on one logical drive, I just High lite and copy to one of 4 Usb/firewire external drives. Operating system and programs are all on CD/DVD's altho you could clone the "C drive"
a c 154 G Storage
March 25, 2009 3:02:45 AM

There seem to be many opinions on raid-0 and partitioning.

My take is to keep it simple.

Partition only if you have a real need to, like several os'es.

Forget about raid-0 unless your workload consists mostly of processing large sequential files.
The os depends on many small random writes, so where you may do better in one area, you will lose in another.

Vista with 8gb is going to keep most of what it needs in ram. Consider the merits of 16 or 24gb of ram. With that amount of ram, vista can keep your entire game in ram also. Just use sleep between sessions instead of powering off and rebooting.

In the spirit full disclosure, I do use raid-0 with two SSD's. I wanted the simplicity of one large "C" drive, and the arm positioning penalty of a hard drive is not there.
March 25, 2009 8:03:40 AM

Ok, so I won't be running anything other than Vista (and maybe Linux) so how about this:

C: Vista + Linux + Programs (200Gb)
D: Swap file (10Gb) - can I hide it?
E: All other data (~1.6Tb)
Spare (~200Gb)

F: 250Gb backup drive

Does that sound reasonable?

With regards to RAM:
- I have 4 RAM slots with 1Gb in each, so 16/24Gb would be difficult (and expensive), would mean replacing the whole lot.
- And I have Geil Black Dragon PC8500, which I'm a little bit attached to!

I'm slightly confused as to why RAID 0 would be less useful than JBOD. The throughput is going to be higher, which can't be a bad thing.

Thanks again for your input

Jeremy
a c 154 G Storage
March 25, 2009 1:28:31 PM

You may be disappointed in the real world(vs. synthetic benchmark) performance benefit of raid-0.
Read this:
http://faq.storagereview.com/tiki-index.php?page=Single...


Keep the 4gb you have. The 16gb was a thought experiment.
However, 8gb is very doable. You can get 4gb kits(2x2gb) of DDR2-800 ram for $20 after rebate.
People will pay a premium for 8500 ram which really does not help performance much. It's value is mainly for overclocking.

Here are some tests for gaming with 6gb vs. 3gb:
http://www.corsair.com/_appnotes/AN811_Gaming_Performan...
a c 352 G Storage
March 25, 2009 2:32:40 PM

First off, concur with geofelt that real world gains for raid0 are normally small. I use Raid0 and am happy with it. Also down stream and with 64 bit Vista, 8 gigs might be beneficial.

My take if you are planing on having two operating system IS NOT to put them on the same drive and requiring a Software boot manager - There are no advantages, ony disadvantages. What I would do if you want Raid0:

Only use 3 of your 500 Gig Drives in a raid array:
Raid array drives 0,1,2 for 1.5 Tbytes
C: 200 Gigs for Vista & programs
D: 1.3 Tbytes for Data/files you create
Drive 3 (500 Gig)
E: 60 to 100 gigs for 2nd operating system (ie playing with Linux)
** see note
F: 8 gigs -> 10 for swap file ( Your call )
G: Remainder of drive for temp/bU
Drive 4
H: or x: All BU, or what ever: (Note I would be tempted - Make that would) remove this drive and place in a USB enclosure

Note: When doing this drive, disconnect your Raid0 drives. Install drive 3 and install your 2nd operating system. It will come up as drive C: when completed reconnect your Vista drive(s). Vista will come up as drive C and linux will now come up as drive E
!