[Users] Extremely poor disk access speeds in Windows guest
Ronen Hod
rhod at redhat.com
Wed Jan 29 09:30:13 UTC 2014
Adding the virtio-scsi developers.
Anyhow, virtio-scsi is newer and less established than viostor (the block device), so you might want to try it out.
A disclaimer: There are time and patches gaps between RHEL and other versions.
Ronen.
On 01/28/2014 10:39 PM, Steve Dainard wrote:
> I've had a bit of luck here.
>
> Overall IO performance is very poor during Windows updates, but a contributing factor seems to be the "SCSI Controller" device in the guest. This last install I didn't install a driver for that device, and my performance is much better. Updates still chug along quite slowly, but I seem to have more than the < 100KB/s write speeds I was seeing previously.
>
> Does anyone know what this device is for? I have the "Red Hat VirtIO SCSI Controller" listed under storage controllers.
>
> *Steve Dainard *
> IT Infrastructure Manager
> Miovision <http://miovision.com/> | /Rethink Traffic/
> 519-513-2407 ex.250
> 877-646-8476 (toll-free)
>
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> ------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
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>
> On Sun, Jan 26, 2014 at 2:33 AM, Itamar Heim <iheim at redhat.com <mailto:iheim at redhat.com>> wrote:
>
> On 01/26/2014 02:37 AM, Steve Dainard wrote:
>
> Thanks for the responses everyone, really appreciate it.
>
> I've condensed the other questions into this reply.
>
>
> Steve,
> What is the CPU load of the GlusterFS host when comparing the raw
> brick test to the gluster mount point test? Give it 30 seconds and
> see what top reports. You'll probably have to significantly increase
> the count on the test so that it runs that long.
>
> - Nick
>
>
>
> Gluster mount point:
>
> *4K* on GLUSTER host
> [root at gluster1 rep2]# dd if=/dev/zero of=/mnt/rep2/test1 bs=4k count=500000
> 500000+0 records in
> 500000+0 records out
> 2048000000 <tel:2048000000> <tel:2048000000 <tel:2048000000>> bytes (2.0 GB) copied, 100.076 s, 20.5 MB/s
>
>
> Top reported this right away:
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 1826 root 20 0 294m 33m 2540 S 27.2 0.4 0:04.31 glusterfs
> 2126 root 20 0 1391m 31m 2336 S 22.6 0.4 11:25.48 glusterfsd
>
> Then at about 20+ seconds top reports this:
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 1826 root 20 0 294m 35m 2660 R 141.7 0.5 1:14.94 glusterfs
> 2126 root 20 0 1392m 31m 2344 S 33.7 0.4 11:46.56 glusterfsd
>
> *4K* Directly on the brick:
> dd if=/dev/zero of=test1 bs=4k count=500000
> 500000+0 records in
> 500000+0 records out
> 2048000000 <tel:2048000000> <tel:2048000000 <tel:2048000000>> bytes (2.0 GB) copied, 4.99367 s, 410 MB/s
>
>
> 7750 root 20 0 102m 648 544 R 50.3 0.0 0:01.52 dd
> 7719 root 20 0 0 0 0 D 1.0 0.0 0:01.50 flush-253:2
>
> Same test, gluster mount point on OVIRT host:
> dd if=/dev/zero of=/mnt/rep2/test1 bs=4k count=500000
> 500000+0 records in
> 500000+0 records out
> 2048000000 <tel:2048000000> <tel:2048000000 <tel:2048000000>> bytes (2.0 GB) copied, 42.4518 s, 48.2 MB/s
>
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 2126 root 20 0 1396m 31m 2360 S 40.5 0.4 13:28.89 glusterfsd
>
>
> Same test, on OVIRT host but against NFS mount point:
> dd if=/dev/zero of=/mnt/rep2-nfs/test1 bs=4k count=500000
> 500000+0 records in
> 500000+0 records out
> 2048000000 <tel:2048000000> <tel:2048000000 <tel:2048000000>> bytes (2.0 GB) copied, 18.8911 s, 108 MB/s
>
>
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 2141 root 20 0 550m 184m 2840 R 84.6 2.3 16:43.10 glusterfs
> 2126 root 20 0 1407m 30m 2368 S 49.8 0.4 13:49.07 glusterfsd
>
> Interesting - It looks like if I use a NFS mount point, I incur a cpu
> hit on two processes instead of just the daemon. I also get much better
> performance if I'm not running dd (fuse) on the GLUSTER host.
>
>
> The storage servers are a bit older, but are both dual socket
> quad core
>
> opterons with 4x 7200rpm drives.
>
>
> A block size of 4k is quite small so that the context switch
> overhead involved with fuse would be more perceivable.
>
> Would it be possible to increase the block size for dd and test?
>
>
>
> I'm in the process of setting up a share from my desktop and
> I'll see if
>
> I can bench between the two systems. Not sure if my ssd will
> impact the
>
> tests, I've heard there isn't an advantage using ssd storage for
> glusterfs.
>
>
> Do you have any pointers to this source of information? Typically
> glusterfs performance for virtualization work loads is bound by the
> slowest element in the entire stack. Usually storage/disks happen to
> be the bottleneck and ssd storage does benefit glusterfs.
>
> -Vijay
>
>
> I had a couple technical calls with RH (re: RHSS), and when I asked if
> SSD's could add any benefit I was told no. The context may have been in
> a product comparison to other storage vendors, where they use SSD's for
> read/write caching, versus having an all SSD storage domain (which I'm
> not proposing, but which is effectively what my desktop would provide).
>
> Increasing bs against NFS mount point (gluster backend):
> dd if=/dev/zero of=/mnt/rep2-nfs/test1 bs=128k count=16000
> 16000+0 records in
> 16000+0 records out
> 2097152000 <tel:2097152000> <tel:2097152000 <tel:2097152000>> bytes (2.1 GB) copied, 19.1089 s, 110 MB/s
>
>
>
> GLUSTER host top reports:
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 2141 root 20 0 550m 183m 2844 R 88.9 2.3 17:30.82 glusterfs
> 2126 root 20 0 1414m 31m 2408 S 46.1 0.4 14:18.18 glusterfsd
>
> So roughly the same performance as 4k writes remotely. I'm guessing if I
> could randomize these writes we'd see a large difference.
>
>
> Check this thread out,
> http://raobharata.wordpress.com/2012/10/29/qemu-glusterfs-native-integration/ it's
> quite dated but I remember seeing similar figures.
>
> In fact when I used FIO on a libgfapi mounted VM I got slightly
> faster read/write speeds than on the physical box itself (I assume
> because of some level of caching). On NFS it was close to half..
> You'll probably get a little more interesting results using FIO
> opposed to dd
>
> ( -Andrew)
>
>
> Sorry Andrew, I meant to reply to your other message - it looks like
> CentOS 6.5 can't use libgfapi right now, I stumbled across this info in
> a couple threads. Something about how the CentOS build has different
> flags set on build for RHEV snapshot support then RHEL, so native
> gluster storage domains are disabled because snapshot support is assumed
> and would break otherwise. I'm assuming this is still valid as I cannot
> get a storage lock when I attempt a gluster storage domain.
>
>
> --------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
>
> I've setup a NFS storage domain on my desktops SSD. I've re-installed
> win 2008 r2 and initially it was running smoother.
>
> Disk performance peaks at 100MB/s.
>
> If I copy a 250MB file from a share into the Windows VM, it writes out
> quickly, less than 5 seconds.
>
> If I copy 20 files, ranging in file sizes from 4k to 200MB, totaling in
> 650MB from the share - windows becomes unresponsive, in top the
> desktop's nfs daemon is barely being touched at all, and then eventually
> is not hit. I can still interact with the VM's windows through the spice
> console. Eventually the file transfer will start and rocket through the
> transfer.
>
> I've opened a 271MB zip file with 4454 files and started the extract
> process but the progress windows will sit on 'calculating...' after a
> significant period of time the decompression starts and runs at
> <200KB/second. Windows is guesstimating 1HR completion time. Eventually
> even this freezes up, and my spice console mouse won't grab. I can still
> see the resource monitor in the Windows VM doing its thing but have to
> poweroff the VM as its no longer usable.
>
> The windows update process is the same. It seems like when the guest
> needs quick large writes its fine, but lots of io causes serious
> hanging, unresponsiveness, spice mouse cursor freeze, and eventually
> poweroff/reboot is the only way to get it back.
>
> Also, during window 2008 r2 install the 'expanding windows files' task
> is quite slow, roughly 1% progress every 20 seconds (~30 mins to
> complete). The GLUSTER host shows these stats pretty consistently:
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 8139 root 20 0 1380m 28m 2476 R 83.1 0.4 8:35.78 glusterfsd
> 8295 root 20 0 550m 186m 2980 S 4.3 2.4 1:52.56 glusterfs
>
> bwm-ng v0.6 (probing every 2.000s), press 'h' for help
> input: /proc/net/dev type: rate
> \ iface Rx Tx
> Total
>
> ==============================================================================
> lo: 3719.31 KB/s 3719.31 KB/s
> 7438.62 KB/s
> eth0: 3405.12 KB/s 3903.28 KB/s
> 7308.40 KB/s
>
>
> I've copied the same zip file to an nfs mount point on the OVIRT host
> (gluster backend) and get about 25 - 600 KB/s during unzip. The same
> test on NFS mount point (desktop SSD ext4 backend) averaged a network
> transfer speed of 5MB/s and completed in about 40 seconds.
>
> I have a RHEL 6.5 guest running on the NFS/gluster backend storage
> domain, and just did the same test. Extracting the file took 22.3
> seconds (faster than the fuse mount point on the host !?!?).
>
> GLUSTER host top reported this while the RHEL guest was decompressing
> the zip file:
> PID USER PR NI VIRT RES SHR S %CPU %MEM TIME+ COMMAND
> 2141 root 20 0 555m 187m 2844 S 4.0 2.4 18:17.00 glusterfs
> 2122 root 20 0 1380m 31m 2396 S 2.3 0.4 83:19.40 glusterfsd
>
>
>
>
>
> *Steve Dainard *
> IT Infrastructure Manager
> Miovision <http://miovision.com/> | /Rethink Traffic/
> 519-513-2407 <tel:519-513-2407> <tel:519-513-2407 <tel:519-513-2407>> ex.250
> 877-646-8476 <tel:877-646-8476> <tel:877-646-8476 <tel:877-646-8476>> (toll-free)
>
> *Blog <http://miovision.com/blog> | **LinkedIn
> <https://www.linkedin.com/company/miovision-technologies> | Twitter
> <https://twitter.com/miovision> | Facebook
> <https://www.facebook.com/miovision>*
> ------------------------------------------------------------------------
> Miovision Technologies Inc. | 148 Manitou Drive, Suite 101, Kitchener,
> ON, Canada | N2C 1L3
> This e-mail may contain information that is privileged or confidential.
> If you are not the intended recipient, please delete the e-mail and any
> attachments and notify us immediately.
>
>
>
>
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>
>
> please note currently (>3.3.1), we don't use libgfapi on fedora as well, as we found some gaps in functionality in the libvirt libgfapi support for snapshots. once these are resolved, we can re-enable libgfapi on a glusterfs storage domain.
>
>
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