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152

This is going to be a function of your workload and the class of drive you purchase... In my server deployments, I have not had a properly-spec'd SSD fail. That's across many different types of drives, applications and workloads. Remember, not all SSDs are the same!! So what does "properly-spec'd" mean? If your question is about SSD use in enterprise ...


54

Every laptop at my work has either a SSDs or Hybrid since 2009. My SSD experience in summary: What I'll call "1st Generation" drives, sold around 2009 mostly: In the first year about 1/4 died, almost all from Syndrome of Sudden Death (SSD - It's funny, laugh). This was very noticeable to end users, and annoying, but the drastic speed difference made this ...


35

I hate to say "don't use SATA" in critical production environments, but I've seen this situation quite often. SATA drives are not generally meant for the duty cycle you describe, although you did spec drives specifically rated for 24x7 operation in your setup. My experience has been that SATA drives can fail in unpredictable ways, often times affecting the ...


26

In the SATA specification this is referred to as hot plug and hot removal and they are two separate events. While the electrical and communication layers support both hot plug and hot removal, check that your drive controller, operating system, and drivers support them. Note that all of the below ONLY applies to host and devices (ie, drive controllers and ...


24

SAS=SCSI=manageability, especially under load and also better prefailure diagnostics and tuning capability. Spendy and low capacity/£$€. SATA=value, capacity and adequate performance for many loads but be aware that 99%+ of SATA drives aren't designed to work 24/7/365 under duress. Also putting them under busy server workloads can dramatically affect their ...


20

A few items to help clarify SAS technology... SATA drives can connect to SAS ports. SAS drives cannot connect to SATA ports. Server-class hardware typically uses an embedded RAID controller or a separate RAID controller PCIe device. Most RAID controllers and SAS HBAs will use SAS connections (multilane or 4-lane SAS ports). Internally, these systems will ...


16

That drive isn't really compatible with Windows XP as it uses a larger 4K sector size - it should explain the performance problems. There's a special alignment tool from WD for Advanced Format drives you need to use or set the correct jumper if it's only going to host one partition. It's really time to upgrade from Windows XP as this kind of workaround ...


15

How can a single disk bring down the array? The answer is that it shouldn't, but it kind of depends on what is causing the outage. If the disk were to die in a way that behaved, it shouldn't take it down. But it's possible that it's failing in an "edge case" way that the controller can't handle. Are you naive to think this shouldn't happen? No, I don't ...


15

The conversion of a SCSI chassis DL380 G4 to the SAS chassis is possible, but not at all practical. It requires a bezel change, backplane modification, a new drive cage, a Smart Array P600 RAID controller (or SAS/SATA HBA) and will be severely crippled in performance. In addition, it can only accommodate 2.5" small-form-factor 1st generation SAS and SATA ...


15

In my experience, the real problem are the dying controllers, not the flash memory itself. I've installed around 10 Samsung SSDs (830, 840 [not pro]) and none of them has made any problems so far. The total opposite are drives with Sandforce controllers, i had several problems with OCZ agility drives, especially freezes in irregular time intervals, where the ...


14

In addition to the problems above, you may have additional issue running these drives in RAID configuration due to the lack of TLER. (If you are considering a model without.) This quote references desktops and the RAID Edition drives but I imagine the same to be true in the 2.5" line if you substitute in "notebook" and "enterprise" or "SAS" where ...


14

Marketing. 7.2K drives are slower and easier to produce, and with higher error thresholds which improves yields (and capacity). However, in terms of I/O operations each discrete disk can support, the 7.2K drives are markedly less performant than their faster brethren. Therefore they get the 'Nearline' moniker, as they'll hit I/O saturation much faster than ...


14

There are two separate parts to your question. Simplifying a bit, a disk consists of the hardware and the controller. Usually when people say "SAS" or "SATA" they are referring to the controller. In principle SAS is a more sophisticated protocol, though in practice for servers with up to say 8 disks there probably isn't much difference between them. Re the ...


14

Generally speaking, in direct answer to your question, I am not aware of any major brands of SATA drives that the drive itself has had bugs relative to proper operation with write caching enabled. That is, from a drive perspective only, the drive does what it is supposed to do from a caching perspective. I would also note that even when write caching is ...


13

This has been covered here... See the related links on the right pane of this question. Right now, the market conditions are such that you should try to use SAS disks everywhere you can. Enterprise SAS disks are your fastest and most resilient rotating media available at 10,000 and 15,000 RPM. Performance-optimized Nearline or Midline SAS are usually ...


13

It works. SATA discs are compatible with SAS. I have tons of them in SAS backplanes. Work like a charm.


13

As ewwhite points out they'll physically fit into the servers with the correct disk caddies but you don't have to look far online to read the tales of woe that people run into when using non-HP disks with HP controllers as HP-branded disks have specific firmware on them that extend the functionality, reliability and in some cases performance of their disks. ...


12

The idea with ZFS is to let it known as much as possible how is disks are behaving. Then, from worst to better: Hardware raid (ZFS has absolutely no clue about the real hardware), JBOD mode (The issue being more about any potential expander: less bandwidth), HBA mode being the ideal (ZFS know everything about the disks) As ZFS is quite paranoid about ...


12

The biggest difference? Failure-rate. Those 'enterprise' drives are warrantied for 5 years, whereas the cheaper ones are probably warrantied for less. Also look into the spec-sheets for them and look at their duty-cycles. The Enterprise drives are designed to run for 5 years straight, where the 'desktop' drives are designed to run 8 hours a day for 5 ...


11

The designers of SATA intended for backwards and forwards compatibility, however, there are some SATA 1 controllers that don't support SATA 2 drives. For this reason, some HD manufacturers added a SATA1/2 mode jumper so that the drives would work with the affected controllers. See this section of the Wikipedia article for relevant chipset info. From that ...


10

Great answer by 1138 but one other aspect of note is that midline driveS usually do not have a '24/365' duty-cycle, this is often hard to spot in the specs but it means that if you drive the disks long and hard they'll fail FAR more frequently than you'd think. As an example we had a ~200 disk array full of 1TB MDLs and saw a >20% failure rate in the first ...


10

Interesting question. dmesg should have something like this if it's a SATA drive: dmesg | grep -i SATA [ 3.972803] ata3: SATA max UDMA/133 cmd 0xe800 ctl 0xe400 bmdma 0xd800 irq 18 [ 3.972807] ata4: SATA max UDMA/133 cmd 0xe000 ctl 0xdc00 bmdma 0xd808 irq 18 I then grep'ed the dmesg output for "ata3" and found the serial number: dmesg | grep ...


10

Normally nothing has changed between the cables between SATA I,II and III. From the official SATA-IO document: The same cables and connectors used for current SATA implementations can be used to connect SATA 6Gb/s devices. SATA-IO recommends utilizing quality components to ensure data integrity and robust operation at the fast 6Gb/s transfer rate. ...


9

Yes, you can. (It's tacky, but it will work) Here's a very good reason not to... But if you choose to move forward... You'll need to place the drive in an HP drive carrier/caddy/tray. This is what secures the disk in the hard drive bay and provides hotplug connections to power and the SATA/SAS connection. This interfaces with the SAS SFF-8482 connector ...


9

You need a SAS expander and/or a server with a disk backplane that has an embedded expander... Please see: RAID card w/1x mini-SAS connector : how do I physically connect 16 disks? and How exactly does a SAS SFF-8087 breakout cable work? + RAID/connection questions


9

The "SATA = 7.2K RPM, SAS = 10/15K RPM" mind-set is strong, and (in my opinion anyway) where most of the "SAS is faster than SATA" thinking comes from. There are some slight differences between SAS and SATA drives, notably in their on-board caching algorithms (NCQ vs. TCQ). However, the performance difference of equivalently specced hard-drives will be ...


9

IOPs is the difference your looking for in the "speed". The simple way to explain the difference is that SATA is half duplex and SAS is full duplex. SATA drives are dumb and have to communicate with the controller for operations. SAS drives are smart and only requests and returns use the bus. Depending on your usage case, spending more may not gain ...


8

I believe that Womble's comment to Peter Schofield is the best observation here...these aren't true SAS disks. No doubt you're being sold "nearline SAS", which is where they take a SATA disk and put a SAS interface on it. The drive mechanics are identical to the SATA version; only the interconnect has changed. When you plug a nearline SAS drive into a ...



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