12H Autoraid

[Nobody's Hero]

If I have a 12H autoraid, and I binf all free space to lun zero and create one large filesystem. Do I still need to define a hot spare? I thought the 12H does all that spare config on its own.

[A. Clay Stephenson · Accepted solution]

You don't assign a disk as a dedicated hot spare. You either enable (-h on) or disable (-h off) active spare via with arraymgr command. With active spare enabled, the amount of free space is decreased but the array then has enough space to automatically rebuild after a failed disk. With active spare disabled, no data will be lost because the redundancy still accounts for all the data bits but if another disk should fail before you replace the first failed disk then data will be lost.

Man arraymgr for details. I can tell you that assigning every bit of the available free space as LUN's has a very significant negative performance impact for these old gals.

[Torsten.]

If you are allocating all the space to a LUN, the performance will be poor and your autoraid is a raid5 array only.

see this thread for performance tuning

http://forums1.itrc.hp.com/service/forums/questionanswer.do?threadId=140045

(around 50% for LUN usage, multiple LUNs, filesystem striping via different hw-pathes)

or search for "autoraid performance".