Expand RAID 10 on Adaptec controllers

[fawrell]

Hi.

We have one old HP server with Adaptec 2200S controller and we want expand one RAID 10 array. But after reading this

http://ask.adaptec.com/scripts/adaptec_tic.cfg/php.exe/enduser/std_adp.php?p_faqid=15127&p_created=1179180656&p_sid=RQ1cc3*i&p_accessibility=0&p_redirect=&p_lva=3835&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MjIsMjImcF9wcm9kcz0wJnBfY2F0cz0wJnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1leHBhbmQgYXJyYXk*&p_li=&p_topview=1

I found out, that RAID 10 can not be expanded. So I searched more and found out here

http://ask.adaptec.com/scripts/adaptec_tic.cfg/php.exe/enduser/std_adp.php?p_faqid=15128&p_created=1179187954&p_sid=RQ1cc3*i&p_accessibility=0&p_redirect=&p_lva=3835&p_sp=cF9zcmNoPTEmcF9zb3J0X2J5PSZwX2dyaWRzb3J0PSZwX3Jvd19jbnQ9MjIsMjImcF9wcm9kcz0wJnBfY2F0cz0wJnBfcHY9JnBfY3Y9JnBfc2VhcmNoX3R5cGU9YW5zd2Vycy5zZWFyY2hfbmwmcF9wYWdlPTEmcF9zZWFyY2hfdGV4dD1leHBhbmQgYXJyYXk*&p_li=&p_topview=1

that I can migrate RAID 1 to RAID 10 adding AT LEAST two drives. So the new array can have 4, 6 ... drives. So why I can't expand RAID 10 array by adding 2 drives, but I can migrate RAID 1 to RAID 10 array by adding 2 and more drives?

[TTr]

Are you sure you can not do what you want? The table in the second URL shows conversions from one raid type to another, you are not converting raid type, you are adding capacity to the same raid type. This operation requires re-striping of the existing raid10 to more disks. This very same operation is taking place in other conversions in that url. Bottom line is you should try it if you have the disks available and as always back up before you start the raid expansion.

[fawrell]

No I'm not sure if I can not do what I want ;-) . Unfortunately I can't try it, because I don't have disks available. I'm just reading the docs before I will do it. And the first url tells me, that I can't expand raid 10, but the second tells me, that I can migrate/convert raid 1 into raid 10 by adding at least two additional drives. Both array expansion and array migration/conversion is done by almost the same way. So why the difference?

[TTr]

So theoretically you could convert your existing array to raid5 add disks and convert back to raid10 right? As I said before the URLs talk about raid type conversion NOT expansion. If you need to add space, you have to buy disks, whether you add them to the existing raid10 or create a new raid1.