6 messages in org.freebsd.freebsd-fslarge disk > 8 TB| From | Sent On | Attachments |
|---|---|---|
| Mark Carlson | Dec 11, 2007 3:20 pm | |
| Ivan Voras | Dec 11, 2007 3:32 pm | |
| Barkley Vowk | Dec 11, 2007 11:53 pm | |
| Dag-Erling Smørgrav | Dec 14, 2007 4:21 am | |
| Ivan Voras | Dec 14, 2007 4:39 am | |
| fluffles.net | Dec 24, 2007 7:45 pm |
| Subject: | large disk > 8 TB | |
|---|---|---|
| From: | fluffles.net (bs...@fluffles.net) | |
| Date: | Dec 24, 2007 7:45:39 pm | |
| List: | org.freebsd.freebsd-fs | |
Ivan Voras wrote:
Barkley Vowk wrote:
It looks like he created a 32bit disk label. He needs to use either the raw device, or gpt partitions I think.
Ie. /dev/mdid1 or /dev/mdid1p1 instead of /dev/mdid1s1
You're right :) I didn't think of checking that - a wrong assumption at my part.
If you are using partitions on a RAID device, you have to make sure you don't end up with a stripe misalignment. If there is misalignment then you end up requiring 2 I/O requests whereas otherwise 1 I/O request would suffice. Naturally this decreases IO performance (less IOps). To avoid a misalignment you have two options:
- not using partitions, but using the raw device like Barkley said - use partitions (GPT or normal) and create one large partition, which starts at offset 1MiB (not MB!) thus 1024*1024 bytes. Note that you probably need to convert this to sectors (512 bytes).
If you do option 2 right, then the partition will start at precisely the start of a new stripe block - thus there is no misalignment. You can use offsets like 64KiB and 128KiB but i prefer to use 1MiB since that will work with all stripesizes (up to 1MiB, which is rarely used).
Merry christmas to all. :)
Regards, Veronica