SAS drive worh it for raid 5

[MikeG]

I was about to upgrade my OS to use 4 15K SAS drives in raid 5 with one drive as spare. I want to use raid 5 for data protection and have a spare drive just in case a drive goes bad. I can get 15K SAS drives for the same price as a SSD thing is the raid 5 does not support trim on my raid controller (Marvell Raid controller on a Lenovo D20) thats why I am going with 15K drives also they come in 300 & 600 gig sizes and are more affordable than an ssd. Will this be as fast as a single ssd? Whats the performance compaired to an ssd. Would 2 SSDs in raid 1 be better? Give me your input.
Mike

 

[hotcrandel]

I was about to upgrade my OS to use 4 15K SAS drives in raid 5 with one drive as spare. I want to use raid 5 for data protection and have a spare drive just in case a drive goes bad.

Backups are better. RAID5 != data protection, it is for uptime and capacity.

I can get 15K SAS drives for the same price as a SSD thing is the raid 5 does not support trim on my raid controller (Marvell Raid controller on a Lenovo D20) thats why I am going with 15K drives also they come in 300 & 600 gig sizes and are more affordable than an ssd.

Does your workstation have onboard intel ports? They may support TRIM in RAID configurations.

Will this be as fast as a single ssd?

Maybe in sequential reads, but otherwise very much no.

Whats the performance compaired to an ssd.

Depends on the controller, but probably not at all close. The Latency difference in SSD's even vs fast spindles is magnitudes of difference.

Would 2 SSDs in raid 1 be better? Give me your input.
Mike

Yes, but the performance wouldn't be better than a single SSD. In general good brand SSD's I'd think are more reliable than mechanical disks.

I'd suggest a single large SSD and backups to a slow HDD (possibly two). Add regular HDD if you need additional storage.

 

[bao__zhe]

I can get 15K SAS drives for the same price as a SSD

If this is the case then i see no reason to go for SAS, even for 15K SAS. SSD without TRIM is still faster and more reliable than SAS - the only exception might be sequential access, as @hotcrandel pointed out.