SAS Drive and Controller Help

[Ste_Harve]

Right i've got a LSI Megaraid SAS 8308ELP with has 5x Fujitsu MAX3174RC's hanging off it in raid 5. One of the drives has failed and I can't find anyone selling these drives. HP sell a refirmwareded version but it shows up as a different size in the bios so won't add it into the raid. The Fujitsu's come in at 140272.0mb and the HP firmwared one is 139815.omb or similar. Does anyone have any ideas as to what other drive we could put in it?

[Michael]

So long as the drive itself is the same spec - RPM, cache etc... you can insert a physically larger drive - a 200GB drive for example. The RAID array would only see 140272.0mb of it and the rest unfortunately would be wasted, but it would work.

[Ste_Harve]

I thought that, but wanted to make sure. Would it have to be the same interface? IE SAS3gbp/s or would a SAS 6gbp/s drive work in it?

[Michael]

Good question - I am presuming the rules for SAS are the same as SATA.

 

They're all compatible with each other, so if you installed a SATA III drive in a SATA II port, it would work at SATA II speeds. I would check with your supplier, but I believe it is the same with SAS.

[Naughty_Nigel]

Good question - I am presuming the rules for SAS are the same as SATA.

 

They're all compatible with each other, so if you installed a SATA III drive in a SATA II port, it would work at SATA II speeds. I would check with your supplier, but I believe it is the same with SAS.

 

It should work [using mixed SATA II and SATA III], as each drive has its own port in SATA; but your array will only be as fast as the slowest drive.

 

Regarding the use of different sized drives; you can create an array using any mixture of drive sizes, but again, the array can only be as big as your smallest drive, and as fast as your slowest drive!

 

Depending on what space you have left over, you can use redundant space to create a simple volume, or (if you have space on two drives), a mirrored volume.

 

When disk space was more expensive and slower than it is now, we often used a simple volume for the OS, on the grounds that we could easily re-install it; but data is more important and more diffucult to replace, so there is good reason to configure an array sch as Raid 5EE which provides redundancy, and will rebuild itself quickly in the event of a drive failure.

 

I have, in the past, also created a clone of the OS disk on a spare hard drive, so that if things go wrong, it is simply a matter of swapping drives to get going again.

 

NN

[Arthur]

The Fujitsu's come in at 140272MB and the HP firmwared one is 139815MB or similar.

Another option is to "cut" the drive using MHDD. This would enable you to resize the Fujitsu drive to exactly 139,815MBs and be transparent to both the OS and RAID controller.

 

hddguru.com/software/2005.10.02-MHDD/mhdd_manual.en.html#hpa