HW RAID and Hotswapping

I think you guys need to re-read the OP. He was asking if you should use hardware raid, or if the hardware part isn't necessary. He then implies that you'll get more downtime for a drive replacement with hardware raid than software raid, and if that's worth it.

For this and many other reasons, I don't recommend hardware raid in general, as it really only provides real benefits in exceptional circumstances. It's one more part to fail, heat up, use power, or cause incompatibilities and software issues, first of all. And secondly, under linux, the software raid has gotten to the stage where there's little or no performance benefit by going hardware raid these days. And, as you said, many raid cards don't support proper hot swapping. I know for some of the cards I've used, you have to completely shut down the system to see a drive change. That said, if you're sloppy about how you configure your bios and system, software raid can suffer the same problem, but at least if you configure it correctly you can get hot swap without too many issues.

For what it's worth, if I were replacing a disk on a raid, I would shut down the server first even if I didn't have to. The last thing you want is to accidentally remove the wrong drive on a running system, but if it's shut down, and you catch your mistake, no harm no foul. To me, being safe than sorry is more useful than avoiding a few minutes of downtime when replacing a failed disk.

If you are using Hardware RAID 1 one on the server and if the primary disk fails/crashes or is due for replacement, then the secondary drive can be connected to the server to make the server function again. Having RAID prevents you from data loss when its mission critical. This process takes a maximum of 30 minutes. Drives used in RAID setup are hotswappable drives. Main advantage of having RAID is that you have a full copy of server's data on the secondary drive. This will make sure that you have atleast one copy left.

Note : RAID won't work if your OS gets corrupted.

Quote:

Originally Posted by huisaydyw

When looking for a server, should I look for one specifically with HW RAID? How do you guys feel about servers having to go down for maintenance when needed to replace failed disks? I mean sure, disks don't fail too often but when they do, the replacement will still warrant a downtime of 30 minutes - 12 hours depending on the host.

I wonder how hosts like Lin0d3 deal with it.

It depends on your requirements. If uptime is critical for you and you can afford it, you'd better go with HW RAID.

Quote:

Originally Posted by huisaydyw

When looking for a server, should I look for one specifically with HW RAID? How do you guys feel about servers having to go down for maintenance when needed to replace failed disks? I mean sure, disks don't fail too often but when they do, the replacement will still warrant a downtime of 30 minutes - 12 hours depending on the host.

I wonder how hosts like Lin0d3 deal with it.

RAID + HOT SWAP drives is one of the most important things for your server reliability

Having a RAID will definitely benefit you. With help of RAID, same data is stored in different places. There are different levels of RAID like RAID 0, RAID 1, RAID 5 etc. The prime advantage of having RAID is that it increases reliability. RAID acts like mirroring and so the changes done in the data are replicated instantly and stored in a different disk or location depending on the RAID level.

Quote:

Originally Posted by HostingSRV

RAID should almost always be used and any reputable web hosting company will have it.

Absoluteley agree. Additionally it will have cache (256MB for example) which could make big difference in IO speed for small read-write operations.

RAID should almost always be used and any reputable web hosting company will have it.

RAID should almost always be used and any reputable web hosting company will have it.