I picked up an old Dell Poweredge 4200 today and it comes with a 6 disk array built into chassis, hot swappable drives, redundant power supplys the whole works. Now I am going to be running redhat on this server (if that matters) and had a question about RAID 5. The drives in the array currently are like this 5 4.3gig and 1 9 gig. If one of those fails can I use either a 9 gig or a 4.3 gig to replace it (and will it rebuild correctly) also how much of a problem is it to upgrade an array one disk at a time. I plan on buying 18.2 Gig drives but because money is tight I will be buying one at a time. Can you easily remove a 4gig drive then insert the 18 gig in its place and still not miss a beat? Any advice/tips/tricks are welcome. Thanks.
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Question about SCSI Raid5
- Thread starter Flagg
- Start date
tiebird321
[H]ard|Gawd
- Joined
- Jun 6, 2004
- Messages
- 1,062
when you build the initial array you set the size per drive
you cannot adjust this once it is set
you can put bigger drives on, but it will be wasted because its still using the smaller drive size
aka
if you start with 5 4.3's forever will the array be 16gb in size
although it may seam cool to be running the 5 drives
running a single 40gb 7.2k will actualy be faster in every application except for mult-ithreaded database apps
here is what would work pretty well for the system
2 4.3's mirrored for Boot
1 4.3 gb Swap
2 4.3gb mirrored for programs
1 9gb for user accounts aka home directory
you cannot adjust this once it is set
you can put bigger drives on, but it will be wasted because its still using the smaller drive size
aka
if you start with 5 4.3's forever will the array be 16gb in size
although it may seam cool to be running the 5 drives
running a single 40gb 7.2k will actualy be faster in every application except for mult-ithreaded database apps
here is what would work pretty well for the system
2 4.3's mirrored for Boot
1 4.3 gb Swap
2 4.3gb mirrored for programs
1 9gb for user accounts aka home directory
Any drive you add will match the size of the smallest drive, and you'd need to support dynamic expansion So if you go from 5x4.5 to 5x4.5+1x9 in the array you will have 18 for the old size and 22.5 for the new, but THAT's only if your controller supports dynamic expansion if it doesn't, you'd have to break the entire array and rebuild it with the new number of drives.
As the others said, there will be no harm in replacing a 4Gb with an 18Gb drive. Every time you do that, the array will have to rebuild before you pull another 4Gb drive.
Do you know what PERC is in that machine? I've found that unless they have the BBU attached they won't let you expand the array, even if they support it.
$25 18Gb SCA drives.
Do you know what PERC is in that machine? I've found that unless they have the BBU attached they won't let you expand the array, even if they support it.
$25 18Gb SCA drives.
The PERC card is the old PERC II model. Or AMI Megaraid 428 i think. Its the base model so it probably doesnt support the dynamic expansion. Thanks for the link to the $25 SCA drives ill have to check that out. I also never thought about "splitting" the array into different parts. Can you actually have 2 or 3 difrent array within one enclosure? Does having the swap partition on the array speed up the system overall? Sorry i f the questiions are a little noobish but I am new to RAID, and am jjust trying to see what im getting into.
Absolutely.Flagg said:Can you actually have 2 or 3 difrent array within one enclosure?
If the enclosure only has 1 channel going into it, the arrays might be fighting for bus bandwidth, but you probably won't notice.
The newer PE's can come with something called a split backplane, where 3 drives will be on one channel, 3 on another. So yo can dedicate an entire u160/320 cable to each.
Moving the swap partition/file onto a second array will speed things up, but if that array goes down it's going to take the machine with it.