Server HDD configuration

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Posted by johny9, 11-28-2011, 08:47 PM
I have a question about server HDD configuration. My current configuration is 1 main SSD (32G) + 2 HDD (1TB X 2 software raid1). Currently, I have my git, php, and ruby program files in SSD and back them up to HDD via cron. Also, big data files are saved in HDD. I kept this configuration for a while but now I came to question myself if SSD is meaningful in this configuration. You see, it might be better to only have 1TBX2 HDD software raid and save all the data into it since data redundancy is kept by software raid. What do you think?
Posted by rik1083, 11-28-2011, 08:59 PM
ssd gives you big speed advantage, u want to lose it? your current setup sounds ok to me as longs as its all backed up like you say?
Posted by Hivelocity-Lee, 11-28-2011, 09:07 PM
Obviously the read/write speeds are the big benefit for using an SSD drive. That being said the failure rate it another Huge benefit, and reason to use an SSD drive. So if your OS is installed on the SSD drive I could see a reason to keep it. Most are finding that using SSD drives for their DB's because of the Read/Write speed. So if you aren't using it for your Databases,(for speed) or your OS isn't already installed on the SSD drive, and being that you are already running a raid 1 configuration for redundancy(though i'm not a fan of software raid) ... then I see no reason for the SSD drive in this case
Posted by shvinod, 11-28-2011, 09:09 PM
But if you are just keeping the program files in SSD, I don't see big speed advantage..
Posted by johny9, 11-28-2011, 09:11 PM
I thought so, too. But when I did some benchmark tests, it seems like SSD is slower than HDD RAID1. -------------------HDD---------------------- #####@######/media$ sudo dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync 16384+0 records in 16384+0 records out 1073741824 bytes (1.1 GB) copied, 9.96438 s, 108 MB/s --------------------------------------- --------------SSD--------------------- #####@#####:/$ sudo dd if=/dev/zero of=test bs=64k count=16k conv=fdatasync 16384+0 records in 16384+0 records out 1073741824 bytes (1.1 GB) copied, 14.448 s, 74.3 MB/s ---------------------------------------------
Posted by johny9, 11-28-2011, 09:13 PM
OS is installed on SSD and big data files and backup is on HDD
Posted by Hivelocity-Lee, 11-28-2011, 09:21 PM
Well here is the thing if you OS is installed on the SSD drive the one benefit is you don't need a Raid for redundancy because the failure rate for SSD is so low... I would keep it, and it would save you from having to reinstall your OS, and just fyi you would have to reconfigure everything if you wanted to use the existing drives and do away with your SSD. I would rather have my OS on an 1 SSD drive than 2 drives configured in a Software Raid. So my point here is you have benefit of the reliability of the SSD drive because it is very unlikely to ever fail
Posted by Hivelocity-Lee, 11-28-2011, 09:23 PM
So in this case forget about the speed, and think about the reliability of the SSD drive never failing... most likely never to fail... you are running a software raid what software are you using to setup this Raid configuration?
Posted by johny9, 11-28-2011, 09:28 PM
mdadm. Just curious. Isn't software RAID 1 of HDD more stable than single SSD?
Posted by johny9, 11-28-2011, 09:40 PM
Again, my point is, 1. benchmark tests show that HDD software RAID1 is faster than SSD. 2. It seems like HDD RAID1 is more stable than SSD. Then why am I using SSD?
Posted by johny9, 11-28-2011, 09:43 PM
And I don't mind spending time to reconfigure my server. Can anyone persuade me that the current setting is better than using only HDD RAID1?
Posted by Hivelocity-Lee, 11-28-2011, 09:57 PM
If you already have your critical data on the drives configured in the Raid configuration, and you can get a reload done fairly easy then doing away with the SSD drive would hurt you at all. So were you planning to do away with a 3rd drive altogether? Or are you planning replacing the SSD drive with a larger SATA drive? The only problem that I could see is if you plan on using only 2 drives(the 2 that are currently configured into a Raid 1 config)... I don't see a way to load the OS on the Raid 1 configuration without breaking the raid config. Maybe I am wrong, but I load servers everyday, however I am not familiar with the Raid software that you are using so maybe it has a way to easily do this.
Posted by Hivelocity-Lee, 11-28-2011, 10:01 PM
So basically in a Raid situation like this. As long as you can backup your data that is currently considered critical(if you have any that is) ... if you can backup the data off of the drives that are currently in a Raid 1 config then it would make it easy to reload the OS onto the drives that would be reconfigured back to a Raid 1 thus doing away with the SSD drive altogether. Now you have your OS loaded on a Raid 1 config with only 2 drives, and all you would need to do is copy the data back over to it.
Posted by johny9, 11-28-2011, 10:05 PM
Yes, I can backup all my data. I am planning to break current RAID setting and configure new one. Would it be better to change my configuration then?
Posted by net, 11-28-2011, 10:14 PM
If you will ask me, I will cancel all the HDD then add 1 more SSD and configure it as software raid1 then get a remote backup :-)
Posted by johny9, 11-28-2011, 10:16 PM
You're right But I am planning to cancel this server soon.
Posted by Hivelocity-Lee, 11-28-2011, 10:20 PM
the problem with adding 1 more SSD drive would be to size limits. Right now he only has a 32gb SSD drive. So if you can find a 1tbx2 SSD drive at a reasonable price then yeah that would be awesome but I don't think so tim. As for configuring your Raid you will need to get all the data off that you need. Then setup a new Raid 1 config. Once that is setup then reload your OS, but partition the drive as needed... You will probably need to partition it for your OS and then different partition/s for your data Hope this helps
Posted by johny9, 11-28-2011, 10:23 PM
It sure did. Thank you!
Posted by Hivelocity-Lee, 11-28-2011, 10:44 PM
Basically in this case the problem with adding a second SSD drive would be the size limitation, and pricing of large SSD drives. Anyway for your Raid config you would basically setup a new Raid 1. So for you Raid you would make sure you have all your data backed up then setup a new raid1 configuration... once that is done you can reload the OS and it will be loaded onto the newly Configured Raid 1. Keep in mind that you may want to partition your hard drive/s for the OS and then a partition for the other files such as program files etc.
Posted by Hivelocity-Lee, 11-28-2011, 10:46 PM
sorry I posted basically the same thing twice... disregard my last post