Sign in with
Sign up | Sign in
Your question

Need help with picking RAID

Last response: in Storage
Share
July 30, 2009 3:04:57 AM

Internal Drives:
3 x 250GB (232)

External Drives:
1TB
2 x 250GB

-------------

The external drives are used for backup purposes with Acronis.

I see some options but I'd like some opinions on pros and cons.

Option 1:
put OS on 1st internal 250GB
Setup a RAID 0 with the other 2 drives for Data.

Option 2:
Setup a RAID 5 with the three drives.

Maybe there's another option I'm missing.

Thanks in advance.

More about : picking raid

a b G Storage
July 30, 2009 5:36:51 AM

I'd go with Option 1. I always believe that it's best to keep your OS drive RAID-free, so that in case your array breaks down, you'll still be able to use your computer. May I suggest getting a smaller drive and installing the OS on it, so that you can use all three 250GBs? How 'bout a 40GB drive?
a c 415 G Storage
July 30, 2009 6:25:18 AM

I'd actually recommend the opposite to r_manic's suggestion. I'd put the OS on a RAID-1 set and the data on last non-RAID disk.

The OS disk is typically the bottleneck, and you'll get some benefit in concurrent I/Os from RAID 1. It will also protect you from a single drive failure so that you can still use your system.

I personally wouldn't use RAID-5 because of the performance penalty on writes.
Related resources
July 30, 2009 3:12:43 PM

i agree with r_manic, non raid for OS and raid for storage
a c 126 G Storage
July 30, 2009 4:39:18 PM

I also agree with r_manic. :) 

Often what's on the system drive doesn't need backupping. Only the personal folders etc. and those can be synchronised to the RAID0 so you have a backup.

Keeping the OS disk out of the RAID might prevent problems if you run into issues with the RAID.
a c 415 G Storage
July 30, 2009 5:27:31 PM

It's interesting to me that you guys are against using RAID for the OS disk because of reliability issues. Is that because you're expecting him to use RAID 0?

I'd certainly agree that RAID 0 on mechanical disks is a poor choice for the OS disk. But I still think there's merit in using RAID 1...
a c 126 G Storage
July 30, 2009 11:39:57 PM

Well we had that discussion in another thread also. And generally for home users its better to just backup data and not use RAID, than to use RAID1. Without going technical here, look at the forums here. You get topics about people with a broken RAID1 and can't access data on both disks. Sure they can recover their files with the right tools and knowledge, but they may not find that in time and decide to delete everything.

Ergo, it protects against more dangers than RAID-1 alone, but at the same disk space cost. In that respect, a backup is superior to RAID-1. But, if uptime is important (for servers) or consumers who are too lazy to backup or even setup automated synchronisation, RAID-1 would be an easy alternative. But not the most reliable. Filesystem corruption would corrupt both copies; i wouldn't want that. :) 

Performance of RAID-1 is also controversial. Most simple implementations offer no performance benefit, at all! Only in hardware RAID, some more advanced proprietary RAID drivers (Intel could be; i have tested only AMD-platform) and Linux/BSD (actually i only tested BSD in this fashion). BSD offers several 'algoritms' in which to perform read requests,

  1. -b balance Specifies balance algorithm to use, one of:
  2.  
  3. load Read from the component with the
  4. lowest load.
  5.  
  6. prefer Read from the component with the
  7. biggest priority.
  8.  
  9. round-robin Use round-robin algorithm when
  10. choosing component to read.
  11.  
  12. split Split read requests, which are big-
  13. ger than or equal to slice size on N
  14. pieces, where N is the number of
  15. active components. This is the
  16. default balance algorithm.


So this driver can do load-balancing and round-robin, both are probably superior to "split" in terms of IOps and throughput.

I would not have any problem using RAID0's on SSDs though. That wouldn't really impact on the reliability of the array and issues with the RAID drivers are more likely than disk failure. Normally, the system drive doesn't hold much personal info that needs to be backupped: Windows, installed applications and games; you don't need to backup those. But you may want to backup My Documents and the samegame folders, for example.
a c 415 G Storage
July 31, 2009 1:07:45 AM

I guess my point of view is that for most people it's a lot easier to back up and restore a data disk than it is to do the same for an OS disk, so if you're going to protect something with RAID it makes more sense to do it for the OS disk. And, in theory at least, even RAID 1 should give you a bit of a performance boost because of increased concurrency for read operations, so again it makes sense to use that for the OS disk which is normally more of a bottleneck.

I read a post somewhere recently in which an Intel engineer claimed that the ICH10R RAID drivers for Windows issued IOs to the drive with the shortest queue. That would be somewhat similar to a round-robin approach, but with the added bonus that it would balance itself better in a situation where some requests take longer than others.

I certainly hear where you're coming from in terms of the "hassles" of RAID. I don't actually use it on my system, either. IMHO you're asking for trouble if you set up a system with RAID and then don't take the time to actually test your recovery procedures - and given my experience with drive failures (which is to say, the lack of them) I really haven't seen it as something worth doing on my home system.
July 31, 2009 1:39:35 AM

Out of all the options I was leaning towards RAID 5 the most since I've used that alot with the DBA stuff I do. I wanted the stability of having one drive fail and still have an operational system until I can replace it.

I understand that there can be a performance issue with going the RAID 5 route and I believe I read on here that putting the OS on a RAID 5 really is slow.

I'm not doing any gaming since I have young children. It's mainly video editing, photo editing, music and database testing for work and continuing education
a b G Storage
July 31, 2009 2:11:20 AM

Occam's Razor: the simplest solution is always the best solution.

(1) choose THE fastest HDD you have and call it "primary";

(2) install your OS on a 30-50GB partition on "primary";
after all software is installed, DEFRAG the OS partition BUT
do NOT DEFRAG your OS partition if it's on an SSD;

(3) format the rest of "primary" as a data partition;

(4) combine at least 2 x 250GB in a RAID 0 for speedy data backups;

(5) after formatting that RAID 0, use the freeware CONTIG program
to create a contiguous swap file "pagefile.sys" using the lowest
possible sector addresses to effect "short armature strokes";
you'll need to change attributes too: attrib pagefile.sys +A+S+H

(6) move your OS swap file to that new "pagefile.sys";

(7) bulk up on RAM so you can create a ramdisk
e.g. RamDisk Plus from www.superspeed.com ;

(8) move all browser caches to that ramdisk;

(9) when you create drive images of your OS partition,
write the drive image file to your RAID 0 (for speed),
then copy that drive image file back to the data
partition on your "primary" HDD (for redundancy).


We use a configuration much like the above,
and it is very fast and reliable, overall.

FYI: the latest enterprise-class HDDs
with perpendicular magnetic recording
are much faster, in general, because
the raw data is passing under the
read/write heads much faster than
with horizontal magnetic recording e.g.:

http://www.newegg.com/Product/Product.aspx?Item=N82E168...


MRFS
July 31, 2009 2:30:50 AM

sminlal said:
I guess my point of view is that for most people it's a lot easier to back up and restore a data disk than it is to do the same for an OS disk, so if you're going to protect something with RAID it makes more sense to do it for the OS disk. And, in theory at least, even RAID 1 should give you a bit of a performance boost because of increased concurrency for read operations, so again it makes sense to use that for the OS disk which is normally more of a bottleneck.

I read a post somewhere recently in which an Intel engineer claimed that the ICH10R RAID drivers for Windows issued IOs to the drive with the shortest queue. That would be somewhat similar to a round-robin approach, but with the added bonus that it would balance itself better in a situation where some requests take longer than others.

I certainly hear where you're coming from in terms of the "hassles" of RAID. I don't actually use it on my system, either. IMHO you're asking for trouble if you set up a system with RAID and then don't take the time to actually test your recovery procedures - and given my experience with drive failures (which is to say, the lack of them) I really haven't seen it as something worth doing on my home system.



And I've been having trouble alot lately where I've had to rebuild my OS several times. Granted, I was running x64 vista the first time, and the second time had a split drive with one partition running x64 vista and Windows 7 RC.

Part of me would still like to have a multiple-boot system where I could possibly run more than one OS without going the VM route...but chances are I'd be better going the VM route with VMWare Virtual Server so that I can run as many as I need too.

I'm starting to wonder now if I may not be better off sticking with 3 X 250 GB hard drives and just leave it at that.

Purely from a video editing aspect, would I benefit most from a RAID 0 on the OS since I'm just using windows movie maker for now and it would be part of the OS?
a c 415 G Storage
July 31, 2009 6:49:28 AM

jason7655 said:
Part of me would still like to have a multiple-boot system where I could possibly run more than one OS without going the VM route...but chances are I'd be better going the VM route with VMWare Virtual Server so that I can run as many as I need too.
If you've got the hardware for it then virtual machines are very nice because you can have them running concurrently. I'm a big multitasker and I'd hate to have to shut down my primary system in order to access a different system.

jason7655 said:
Purely from a video editing aspect, would I benefit most from a RAID 0 on the OS since I'm just using windows movie maker for now and it would be part of the OS?
Using RAID 0 on the disk that has the software installed on it would probably help it to load faster, but it won't make much (if any) difference while you're actually using it. The way to improve the running performance would be to make sure that it's work files are on the fastest drive you have.

Of course you'll get the very best performance if you have lots and lots of RAM so as to minimize the need for the software to use its work files in the first place.
!