If this is your first visit, be sure to check out the FAQ by clicking the link above. You may have to register before you can post: click the register link above to proceed. To start viewing messages, select the forum that you want to visit from the selection below. |
|
|
Thread Tools | Display Modes |
#1
|
|||
|
|||
Raid suggestions?
Hello,
We have just bought Dell MD1000, together with 15 SAS 15K hard disks. This server will be connected to 6 web servers which provide a centralized storage using NFS. This server is important as if it down, other web servers didn't work so I need to consider if which Raid configuration is better choice? Assume it is 80% rad, 20% write, and average file size is around 30-50KB. Total capactity is important so we don't consider RAID 10. Should I set RAID50 for my server? Or Raid6? Thanks. |
#2
|
|||
|
|||
Raid suggestions?
howa wrote:
Hello, We have just bought Dell MD1000, together with 15 SAS 15K hard disks. This server will be connected to 6 web servers which provide a centralized storage using NFS. This server is important as if it down, other web servers didn't work so I need to consider if which Raid configuration is better choice? Assume it is 80% rad, 20% write, and average file size is around 30-50KB. Total capactity is important so we don't consider RAID 10. Should I set RAID50 for my server? Or Raid6? Well, you could back up and reconsider your purchase decision, since you could quite possibly get higher capacity, better performance, and better availability at lower cost using (more) SATA drives in RAID-10. Assuming that's not an option, then if availability is as important as you suggest RAID-6 might be best - especially if the hardware will shut down the RAID-5 array if a disk fails and it encounters a bad sector while rebuilding (I've never understood why arrays would do this rather than just report the bad sector and continue, just as would happen with an individual disk, but many apparently do). - bill |
#3
|
|||
|
|||
Raid suggestions?
Hello,
On Apr 24, 8:06*pm, Bill Todd wrote: howa wrote: Assuming that's not an option, then if availability is as important as you suggest RAID-6 might be best - especially if the hardware will shut down the RAID-5 array if a disk fails and it encounters a bad sector while rebuilding (I've never understood why arrays would do this rather than just report the bad sector and continue, just as would happen with an individual disk, but many apparently do). - bill Well, how about Raid 50? I read some of the posts in this group and seems people don't like it very much? |
#4
|
|||
|
|||
Raid suggestions?
howa wrote:
Hello, On Apr 24, 8:06 pm, Bill Todd wrote: howa wrote: Assuming that's not an option, then if availability is as important as you suggest RAID-6 might be best - especially if the hardware will shut down the RAID-5 array if a disk fails and it encounters a bad sector while rebuilding (I've never understood why arrays would do this rather than just report the bad sector and continue, just as would happen with an individual disk, but many apparently do). - bill Well, how about Raid 50? RAID-50 shares the basic failure characteristics of RAID-5: it's just 2 or more RAID-5 arrays bound together with RAID-0-style striping on top. This does lower (but not dramatically) the probability that a bad sector will be found during a rebuild after a disk fails (or that a second disk in the same RAID-5 group will fail before the rebuild completes) - and if either occurs your system still becomes unavailable (unless the array can tolerate finding a bad sector during rebuild). RAID-50 also tends to mitigate the performance hit that the system takes before a failed disk has been replaced and rebuilt. IMO RAID-50 is a good solution if the array logic will permit a rebuild to complete even if a bad sector is encountered, because that's by far the major threat with today's disk sizes: as long as there aren't too many disks in each group the likelihood of a second whole-disk failure within that group before a rebuild completes is pretty small, and RAID-50 lets you limit the RAID-5 group sizes to a reasonable value (say, under 10) that still gives you good space efficiency. Of course, that will still leave you with a potentially unavailable file (unless the bad sector happens to be in free space), so you'll need to find out where it is and then rewrite the file (e.g., from a backup copy) to make it fully-accessible again. - bill |
Thread Tools | |
Display Modes | |
|
|
Similar Threads | ||||
Thread | Thread Starter | Forum | Replies | Last Post |
REQ: Suggestions for AMD RAID Motherboard | [email protected] | Homebuilt PC's | 5 | July 11th 07 08:52 AM |
RAID Motherboard Suggestions | spodosaurus | Homebuilt PC's | 1 | August 26th 05 03:56 PM |
AMD based RAID 1 Motherboard Suggestions | Nigel Smith | Homebuilt PC's | 0 | March 19th 05 09:31 AM |
RAID suggestions? | Noozer | General | 5 | July 2nd 04 05:57 AM |
Suggestions please - RAID on accounts server | bluboxthief | Storage & Hardrives | 0 | May 5th 04 02:48 PM |