SAS Drive Upgrades

By EXCellR8 ยท 9 replies
Sep 17, 2013
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  1. We have a small PowerEdge 2900 server at the office with 3x 140GB SAS drives and we need more space. I'm trying to figure out how the data is arranged because we only have ~272GB total for file storage. Our needs are minimal we basically just need to store lots of smaller files mostly just a few MB in size. There is basically a single directory that we read/write to on the server.

    I'm basically trying to figure out if getting bigger SAS drives (expensive) vs. simply downsizing to a Xeon-based desktop PC with a set of maybe four 500GB drives, RAID-10, would be better. We do need redundancy at some level but I think performance with regular SATA drives would be just fine for us. There are maybe 5-8 people using opening or saving files to the server at any given time...

  2. jobeard

    jobeard TS Ambassador Posts: 11,177   +990

    RAID is an issue. Expanding Raid-0 or Raid-10 is not just adding one more HD to the enclosure. A RAID-JBOD setup will allow adding more devices without rebuilding the entire RAID.

    There are multiple solutions for redundancy and/or backups.

    Personally, I like staging the redundant data from the SAS device and not the original sources, which reduces the load on the originals and the redundant copies can be sync'd overnight without impact to the active users:

    ( PC users ) === network === SAS
    		  ||		|
    		  ||		sync
    		  ||		|
    		  ||		V
    		  + === Redundant Device
    [edit] oh yea: offsite backups can then be staged from
    Redundant Device - - - > iCloud storage[/edit]
  3. St1ckM4n

    St1ckM4n TS Evangelist Posts: 2,922   +630

    SAS drives are enterprise-grade, SATA is workstation-grade. Your experience will reflect this.

    You probably have your drives set up in RAID5 right now. That's a decent array arrangement. My suggestions:

    1. Buy 3x new SAS drives and a tape drive. Use tape for overnight incremental backups and perhaps off-site.
    2. Buy tape drive, move old data to this. Allows you to use current drives. May not be possible if you still need access to all data.

    At the end of the day, it's your data and your security. The amount of money you spend on a suitable solution will directly impact any problems you may have.
  4. EXCellR8

    EXCellR8 The Conservative Topic Starter Posts: 1,835

    Yea sorry I probably should have clarified that I don't want to add drives, but replace the existing with bigger ones. I do think it is RAID-5 the console shows the 3x 140GB drives and a virtual ~272GB drive... so is that just stating that two are combined and there is one parity drive or something? I was scratching my head over that earlier.

    At this point since our read/write is so minimal, I may just invest in NAS and leave the server alone. Pair a couple of 500GB drives (plenty of space) and just use RAID-1. Done.
  5. St1ckM4n

    St1ckM4n TS Evangelist Posts: 2,922   +630

    Look at wikipedia for RAID definitions.

    Also, what's the application that uses this data? It may not be suitable for NAS.

    You get what you pay for ...
  6. EXCellR8

    EXCellR8 The Conservative Topic Starter Posts: 1,835

    It's mostly CAD drawings and PDF's... there is basically one shared directory on the server that is simply mapped on each workstation. Pretty basic and primitive setup but that's all we need at the moment, just more space.
  7. GhostRyder

    GhostRyder This guy again... Posts: 2,198   +593

    Wait I was reading your article and you say you have 3x140gb SAS drives yet your total file storage is only 272? In the most basic sense, you should have 420gb of space max minus probably 15gb for OS and other junk so I would say either you have a drive problem or the RAID is setup incorrectly.

    With Dell PowerEdge 2900 series servers the machines are a little interesting when setting up raid though I believe Dell should have set it up properly if it came with those three drives installed. You might want to check as to why that other drive is not being detected in the array as that could point to an issue.

    As for whether to swap from SAS to just a machine that has 4 500gb drives (Probably 7200RPM), for your needs, I would just stick with what you have, add more SAS drives to the Array as this way you will have the same setup and wont be sacrificing any of the performance and quality that comes with a SAS setup of drives (You will probably notice a difference). Plus grabbing a few more 140gb drives is not too bad price wise compared to a whole new machine. I would also suggest setting a backup for the machine (You can do that in a different raid config is needed) as that will help save your data in case of an emergency.

    The reason I like a lot of smaller drives in a raid controller versus having a couple big drives on important Data, is that if one big drive fails, you have the bigger potential to have data loss versus losing one small drive from the array. I have seen so many times where an agency at the data center I work will put in a machine with 2 500gb drives in raid and has one fail to lose tons of information. Then I will see one machine that they call me on for having 5 failed drives yet no loss of data because they have 10 drives that are like 80gb in size on the one controller.
  8. EXCellR8

    EXCellR8 The Conservative Topic Starter Posts: 1,835

    Yes I know, that is what caused my confusion when I initially had a look at the machine. It didn't make sense that I only had 272GB usable when all 3 drives were showing online status. Unfortunately I wasn't working here when the machine was set up so I don't really have any specific configuration info. I put in a call to the company who supplied the server but I have yet to hear back. Chances are they will just refer me to Dell anyway.

    What you are saying with drive capacity makes sense, and I wouldn't have an issue with simply adding more drives. It's just the current configuration that raises a little suspicion I need to get to the bottom of that. Also, what is the approximate availability of smaller SAS drives? I'm digging through boxes and I don't seem to have the hot-swap hardware so I would probably need to find that too.
  9. St1ckM4n

    St1ckM4n TS Evangelist Posts: 2,922   +630

    You guys didn't read the wikipedia article, did you? :p

    RAID is not just.... RAID. There's multiple types of RAID implementations. OP probably has RAID5. Storage capacity for this is:

    [​IMG], where [​IMG] is the total number of drives in the array and [​IMG] is the capacity of the smallest drive in the array.

    (3 - 1) x 140 = 2 x 140 = 280GB (raw)
    OP, you can extend your RAID5 array by adding more 140GB disks, but you will need to see how many SAS ports are available on your RAID controller.

    Additionally, the chance of a drive failing is not proven to be higher in 200GB+ capacities, AFAIK. Also, the chance of the array failing is related to the number of disks in the array, not the capacity of disks/array.

    A high-quality NAS will be okay for your purposes of PDF's and CAD files. I'm not sure that will fix anything though, and will just be an additional cost.

    Just make sure you have shadow copy turned on, on the server. And get that tape drive for incremental backups plus off-site storage.
  10. EXCellR8

    EXCellR8 The Conservative Topic Starter Posts: 1,835

    That makes sense; the server is definitely RAID5 then.

    Simply extending the array with more 140GB SAS is the quickest way, but I'm not sure I can even get the drives anymore. Backups are made regularly, maybe even daily, so we can still use the server for that as we are now. I'll ask the rest of my department what they want to go with and ultimately let them choose.

    Thanks for the input!

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