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  • Cost Comparison Hard Disk Drive to Solid State Drive on Price per Gigabyte - dispelling a myth!

    - by tonyrogerson
    It is often said that Hard Disk Drive storage is significantly cheaper per GiByte than Solid State Devices – this is wholly inaccurate within the database space. People need to look at the cost of the complete solution and not just a single component part in isolation to what is really required to meet the business requirement. Buying a single Hitachi Ultrastar 600GB 3.5” SAS 15Krpm hard disk drive will cost approximately £239.60 (http://scan.co.uk, 22nd March 2012) compared to an OCZ 600GB Z-Drive R4 CM84 PCIe costing £2,316.54 (http://scan.co.uk, 22nd March 2012); I’ve not included FusionIO ioDrive because there is no public pricing available for it – something I never understand and personally when companies do this I immediately think what are they hiding, luckily in FusionIO’s case the product is proven though is expensive compared to OCZ enterprise offerings. On the face of it the single 15Krpm hard disk has a price per GB of £0.39, the SSD £3.86; this is what you will see in the press and this is what sales people will use in comparing the two technologies – do not be fooled by this bullshit people! What is the requirement? The requirement is the database will have a static size of 400GB kept static through archiving so growth and trim will balance the database size, the client requires resilience, there will be several hundred call centre staff querying the database where queries will read a small amount of data but there will be no hot spot in the data so the randomness will come across the entire 400GB of the database, estimates predict that the IOps required will be approximately 4,000IOps at peak times, because it’s a call centre system the IO latency is important and must remain below 5ms per IO. The balance between read and write is 70% read, 30% write. The requirement is now defined and we have three of the most important pieces of the puzzle – space required, estimated IOps and maximum latency per IO. Something to consider with regard SQL Server; write activity requires synchronous IO to the storage media specifically the transaction log; that means the write thread will wait until the IO is completed and hardened off until the thread can continue execution, the requirement has stated that 30% of the system activity will be write so we can expect a high amount of synchronous activity. The hardware solution needs to be defined; two possible solutions: hard disk or solid state based; the real question now is how many hard disks are required to achieve the IO throughput, the latency and resilience, ditto for the solid state. Hard Drive solution On a test on an HP DL380, P410i controller using IOMeter against a single 15Krpm 146GB SAS drive, the throughput given on a transfer size of 8KiB against a 40GiB file on a freshly formatted disk where the partition is the only partition on the disk thus the 40GiB file is on the outer edge of the drive so more sectors can be read before head movement is required: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 3,733 IOps at an average latency of 34.06ms (34 MiB/s). The same test was done on the same disk but the test file was 130GiB: For 100% sequential IO at a queue depth of 16 with 8 worker threads 43,537 IOps at an average latency of 2.93ms (340 MiB/s), for 100% random IO at the same queue depth and worker threads 528 IOps at an average latency of 217.49ms (4 MiB/s). From the result it is clear random performance gets worse as the disk fills up – I’m currently writing an article on short stroking which will cover this in detail. Given the work load is random in nature looking at the random performance of the single drive when only 40 GiB of the 146 GB is used gives near the IOps required but the latency is way out. Luckily I have tested 6 x 15Krpm 146GB SAS 15Krpm drives in a RAID 0 using the same test methodology, for the same test above on a 130 GiB for each drive added the performance boost is near linear, for each drive added throughput goes up by 5 MiB/sec, IOps by 700 IOps and latency reducing nearly 50% per drive added (172 ms, 94 ms, 65 ms, 47 ms, 37 ms, 30 ms). This is because the same 130GiB is spread out more as you add drives 130 / 1, 130 / 2, 130 / 3 etc. so implicit short stroking is occurring because there is less file on each drive so less head movement required. The best latency is still 30 ms but we have the IOps required now, but that’s on a 130GiB file and not the 400GiB we need. Some reality check here: a) the drive randomness is more likely to be 50/50 and not a full 100% but the above has highlighted the effect randomness has on the drive and the more a drive fills with data the worse the effect. For argument sake let us assume that for the given workload we need 8 disks to do the job, for resilience reasons we will need 16 because we need to RAID 1+0 them in order to get the throughput and the resilience, RAID 5 would degrade performance. Cost for hard drives: 16 x £239.60 = £3,833.60 For the hard drives we will need disk controllers and a separate external disk array because the likelihood is that the server itself won’t take the drives, a quick spec off DELL for a PowerVault MD1220 which gives the dual pathing with 16 disks 146GB 15Krpm 2.5” disks is priced at £7,438.00, note its probably more once we had two controller cards to sit in the server in, racking etc. Minimum cost taking the DELL quote as an example is therefore: {Cost of Hardware} / {Storage Required} £7,438.60 / 400 = £18.595 per GB £18.59 per GiB is a far cry from the £0.39 we had been told by the salesman and the myth. Yes, the storage array is composed of 16 x 146 disks in RAID 10 (therefore 8 usable) giving an effective usable storage availability of 1168GB but the actual storage requirement is only 400 and the extra disks have had to be purchased to get the  IOps up. Solid State Drive solution A single card significantly exceeds the IOps and latency required, for resilience two will be required. ( £2,316.54 * 2 ) / 400 = £11.58 per GB With the SSD solution only two PCIe sockets are required, no external disk units, no additional controllers, no redundant controllers etc. Conclusion I hope by showing you an example that the myth that hard disk drives are cheaper per GiB than Solid State has now been dispelled - £11.58 per GB for SSD compared to £18.59 for Hard Disk. I’ve not even touched on the running costs, compare the costs of running 18 hard disks, that’s a lot of heat and power compared to two PCIe cards!Just a quick note: I've left a fair amount of information out due to this being a blog! If in doubt, email me :)I'll also deal with the myth that SSD's wear out at a later date as well - that's just way over done still, yes, 5 years ago, but now - no.

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  • Free Mac whole disk encryption

    - by stevekuo
    Are there any free solutions for encrypting the entire boot disk on a Mac? I'm aware of PGP's Whole Disk Encryption, but it's a bit steep at $149. TrueCrypt's System Encryption seems to only work with Windows.

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  • Disk drive disappear in Windows Explorer

    - by Stan
    OS: WinXP SP3 When pressing win+E or open Windows Explorer, under My Computer, usually there are several disk drives. But somehow they just disappeared. If I type c:\ in address bar, then the disk will re-appear in the tree though. How to get them back? Thanks.

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  • Disk usage treemap software for headless Linux

    - by CyberShadow
    There are some programs which can display used disk space using a treemap, such as WinDirStat for Windows and KDirStat for KDE/Linux: I'm looking for something similar, but for a headless Linux box. Alternatively, what are other good ways to visualize used disk space with just SSH access?

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  • PHP crashing on occasion - APC error?

    - by papanel
    Any thoughts on this? We've had this happen twice recently. Basically, every page throws a fatal error, fixed by an apache restart. Here's what's in the log, repeated over and over. [Tue Apr 13 15:18:12 2010] [error] [client 10.0.0.2] PHP Fatal error: Internal Zend error - Missing class information for in /www/sites/ep/vogoo/items.php on line 31 [Tue Apr 13 15:18:12 2010] [error] [client 10.0.0.2] PHP Fatal error: Internal Zend error - Missing class information for in /www/sites/ep/vogoo/items.php on line 31 [Tue Apr 13 15:18:13 2010] [error] [client 10.0.0.2] PHP Fatal error: Internal Zend error - Missing class information for in /www/sites/ep/vogoo/items.php on line 31 Looking around, this may be an issue with APC? http://pecl.php.net/bugs/bug.php?id=16120&edit=1 (We're running 3.0.19, which shows as latest stable on pecl.) Thoughts? I increased the amount of memory apc uses, but the problem just happened again.

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  • Postfix : error: unsupported dictionary type: mysql

    - by flavio.troja
    I've a problem w/ postfix problem: # tail -f /var/log/mail.err Aug 20 17:57:50 myserver postfix/smtpd[8243]: error: unsupported dictionary type: mysql Aug 20 17:57:50 myserver postfix/smtpd[8243]: error: unsupported dictionary type: mysql Aug 20 17:58:05 myserver postfix/smtpd[8244]: error: unsupported dictionary type: mysql Aug 20 17:58:05 myserver postfix/smtpd[8244]: error: unsupported dictionary type: mysql Aug 20 18:00:38 myserver postfix/smtpd[8277]: error: unsupported dictionary type: mysql Aug 20 18:00:38 myserver postfix/smtpd[8277]: error: unsupported dictionary type: mysql Aug 20 18:03:32 myserver postfix/smtpd[8320]: error: unsupported dictionary type: mysql Aug 20 18:03:32 myserver postfix/smtpd[8320]: error: unsupported dictionary type: mysql Aug 20 18:03:33 myserver postfix/trivial-rewrite[8322]: error: unsupported dictionary type: mysql Aug 20 18:03:33 myserver postfix/trivial-rewrite[8322]: error: unsupported dictionary type: mysql idea?

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  • PLesk Error: pmm-ras error (Error code = -6): during restore.. /tmp folder to increase?

    - by eric
    I had to re-install plesk on a centos 6 system after a crash. The full backup file is 11 gb. but at the beginning of the backup reinstall I get the error Error: pmm-ras error (Error code = -6): argh ! my disk organization is like this Filesystem Size Used Avail Use% Mounted on /dev/xvda1 3.7G 801M 2.9G 22% / /dev/mapper/vg00-usr 14G 1.5G 12G 12% /usr /dev/mapper/vg00-var 155G 14G 134G 10% /var /dev/mapper/vg00-home 3.9G 136M 3.6G 4% /home none 1000M 7.5M 993M 1% /tmp I suppose I have to increase my /tmp folder to accept the backup size,but I don't know how-to. I'm on 1&1 cloud server Thanks for your help. You can imagine the emergency of this situation...

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  • Installing Windows 7 upgrade version on a clean disk

    - by BobMarley
    Is it possible to install the much cheaper Windows 7 upgrade version on a clean disk? What information will I need? 1) Will the Windows 7 installer ask me for my XP license key? or 2) Will the Windows 7 installer only run if it can detect an existing XP installation? Furthermore, what will happen if my disk crashes and I need to reinstall in the future? Will I need my XP license key again?

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  • Using SSD as disk cache

    - by casualcoder
    Is there software for Linux to use an SSD as disk cache? I believe that Sun does something like this with ZFS, though not sure. A quick search provides nothing suitable. The goal would be to put frequently requested files on the SSD on-the-fly. Since the SSD has more capacity than RAM for less money and better performance than hard disk, this should provide an efficient performance boost.

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  • Hard disk number in boot.ini?

    - by MA1
    Hi All Need help to remove a confusion. Suppose we have two hard disk. Referring to boot.ini, In case of MULTI and SCSI syntax: which parameter exactly tells us hard disk number? Regards,

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  • How to measure disk-performance under Windows?

    - by Alphager
    I'm trying to find out why my application is very slow on a certain machine (runs fine everywhere else). I think i have traced the performance-problems to hard-disk reads and writes and i think it's simply the very slow disk. What tool could i use to measure hd read and write performance under Windows 2003 in a non-destructive way (the partitions on the drives have to remain intact)?

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  • Hard disk with trustworthy SMART support

    - by Paggas
    Which hard disk drive do you suggest with trustworthy SMART diagnostics? That is, a hard disk that can truthfully report sector reallocations and other pre-failure indicators. I'm asking this because I have seen quite a few hard disks with SMART support fail with no warning in the SMART diagnostics, so a hard drive that can report such problems with some degree of reliability would be much appreciated :)

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  • RunDLL error Hard Disk Drive

    - by stanleyenriquez
    I can't open my hard disk drive. The error box says "RUnDLL, there was a problem starting ~$WCFLPM.FAT32 The specified module could not be found". My HDD has a virus before. My hard disk contains a shortcut and the shortcut contains all files. I don't want to format it just yet because it contains quite many files. I tried troubleshooting it but none of the solutions in the internet helped.

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  • When to use a RAM-Disk?

    - by Ice
    Hi, I know that RAM-Disk are fast, faster than any Disk but they lose their contents on a shutdown of the operating system. The capacity is limited to the RAM. Is there a usefull implementation on a new 64-Bit windows 2008 server? Peace Ice

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  • mac external-hard-disk "software update"

    - by Pietro
    When I make a software update, the files are downloaded on my MacBook's internal hard disk. How can I set a different hard disk as default? I suppose the files related to the software update are compressed packages that have to be saved, opened and decompressed. I would like to use the internal HD just to update MacOS, without storing any temporary files. Thank you! Pietro MacBook Pro 2009, 256 GB SSD, MacOSX 10.6.4

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  • hp proliant dl360 disk diagnostic issue

    - by user1039384
    We recently got two used drives (15000) and installed on our HP proliant dl360 G5 server. Created RAID1 and used HP SmartStart CD to perform diagnostics. Interestingly, the Diagnostic tab immidiately fails on Logical drive testing saying the Disk1 should be replaced, while the Test tab successfully runs all the complete tests on both disks and does not find any issue. At the meantime, when booting to esxi 5, vSphere periodically shows the Disk1 as Unknown and Logical drive in recovery process. This happens every 5-10 minutes. Here is the log from HP SmartScan diagnostic: 1 - Device, Test: Logical Drive 1, Storage Controller in Slot 0 1 - Description: The controller has reported a critical error in the drive error log. 1 - Recommended Repair: This drive should be replaced. 1 - Failed Count: 44 1 - Error code: F157 There is also another error log record (see below): 2 - Device, Test: test_components/libstorage.so ID 2 - Description: An unexpected exception occurred while performing an operation. Exception message: CISS_StatusHandler::evaluate: commandStatus = 4 (INVALID); hexdump of CISS_ErrorInfo: 00000000: __ __ 04 __ 20 __ __ __ __ __ __ __ __ __ __ __ .... ... ........ 00000010: __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ........ ........ 00000020: __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ __ ........ ........ Device: Hard Drive 2, Storage Controller in Slot 0 Property name: Bad Target Count 2 - Recommended Repair: Reboot or restart Insight Diagnostics. Retry the test. If the problem persists, upgrade to the latest version of Insight Diagnostics. 2 - Failed Count: 48 2 - Error Code: F62 Note that rebooting didn't help and I was running the latest diagnostic software version. Anyone has a clue? Is this a real disk issue? BTW, the controller is Smart Array E200i Thanks in advance

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  • How to clear Windows disk read cache?

    - by Sebastiaan Megens
    For performance testing I need to clear Windows' disk read cache. I tried googling but I couldn't find anything other than rebooting or other manual stuff. Before I give in and do that, I'd like to know if anyone knows of a way to clear Windows disk read cache. I'm testing on Windows 7, but I'm also interested in Windows XP solutions.

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  • Blaze error: No disk in drive

    - by jruday
    Running Blaze on Win 7 64-bit PC and getting the following error: There is not disk in the drive. Please insert a disk into drive\Device\Harddisk2\DR2. View error message here: http://screencast.com/t/ZjQxNDc0NW. Any suggestions would be appreciated. Thanks.

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  • external disk suddenly unmounting

    - by hasen j
    Platform: Ubuntu 9.10 Disk Brand/model: WD My Book The external hard disk suddenly unmounts after a while. I suspect it's due to it "sleeping" to save power. I don't recall the problem having occurred before the upgrade to Karmic. How can this be fixed?

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  • How to make password reset disk windows

    - by Mirage
    I don't have floppy drive on my computer. Is there any way that i can make the password reset disk in a folders so that when i lose my passowrd then i can choose that folder to work as password reset disk. Is there any other option available beside Floppy drive

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  • IE on Windows 7 not saving files to disk [closed]

    - by Gemini
    I am running Win 7 Build 7100. Since I restored this system I am facing peculiar issues - all effectively rendering this system unusable. The biggest peeve is: Any file downloaded from IE is never saved to disk. IE shows the entire download progress bar and at the end of download, no file is saved anywhere on the disk!

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  • Linux filesystem with inodes close on the disk

    - by pts
    I'd like to make the ls -laR /media/myfs on Linux as fast as possible. I'll have 1 million files on the filesystem, 2TB of total file size, and some directories containing as much as 10000 files. Which filesystem should I use and how should I configure it? As far as I understand, the reason why ls -laR is slow because it has to stat(2) each inode (i.e. 1 million stat(2)s), and since inodes are distributed randomly on the disk, each stat(2) needs one disk seek. Here are some solutions I had in mind, none of which I am satisfied with: Create the filesystem on an SSD, because the seek operations on SSDs are fast. This wouldn't work, because a 2TB SSD doesn't exist, or it's prohibitively expensive. Create a filesystem which spans on two block devices: an SSD and a disk; the disk contains file data, and the SSD contains all the metadata (including directory entries, inodes and POSIX extended attributes). Is there a filesystem which supports this? Would it survive a system crash (power outage)? Use find /media/myfs on ext2, ext3 or ext4, instead of ls -laR /media/myfs, because the former can the advantage of the d_type field (see in the getdents(2) man page), so it doesn't have to stat. Unfortunately, this doesn't meet my requirements, because I need all file sizes as well, which find /media/myfs doesn't print. Use a filesystem, such as VFAT, which stores inodes in the directory entries. I'd love this one, but VFAT is not reliable and flexible enough for me, and I don't know of any other filesystem which does that. Do you? Of course, storing inodes in the directory entries wouldn't work for files with a link count more than 1, but that's not a problem since I have only a few dozen such files in my use case. Adjust some settings in /proc or sysctl so that inodes are locked to system memory forever. This would not speed up the first ls -laR /media/myfs, but it would make all subsequent invocations amazingly fast. How can I do this? I don't like this idea, because it doesn't speed up the first invocation, which currently takes 30 minutes. Also I'd like to lock the POSIX extended attributes in memory as well. What do I have to do for that? Use a filesystem which has an online defragmentation tool, which can be instructed to relocate inodes to the the beginning of the block device. Once the relocation is done, I can run dd if=/dev/sdb of=/dev/null bs=1M count=256 to get the beginning of the block device fetched to the kernel in-memory cache without seeking, and then the stat(2) operations would be fast, because they read from the cache. Is there a way to lock those inodes and/or blocks into memory once they have been read? Which filesystem has such a defragmentation tool?

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  • Disk usage treemap software for headless Linux

    - by CyberShadow
    There are some programs which can display used disk space using a treemap, such as WinDirStat for Windows and KDirStat for KDE/Linux: I'm looking for something similar, but for a headless Linux box. (E.g. run console data collection program on the server, then load the file in a graphical program in a GUI environment.) Alternatively, what are other good ways to get a structured used disk space representation, with just SSH access?

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  • BSOD constantly with same ntoskrnl.exe error and disk indicator is frozen

    - by Sheep
    BSOD constantly and the disk indicator is frozen. Error do not happen immediately, usually an hour after boot up. Here is the Minidump: Bug Check Code = 0x00000124 Caused By Driver = ntoskrnl.exe Caused By Address = ntoskrnl.exe+4b094c Crash Address = ntoskrnl.exe+4b094c Seems to be hardware problem, but I checked RAM, no error. I have two HDs installed, system is on SSD, data is on HDD. Checked SSD with the properties-tools-error-checking , no error. Re-installed several times, still happens even after removed HDD. Configuration: SSD: Crucial M4-CT064M4SSD2 with Firmware 0009 Intel HM65 CPU: i7-2630QM The SSD is set correctly, SATA III 6Gb/s enabled, and everything worked perfectly for nearly a year.

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